diff --git a/hw04/CMakeLists.txt b/hw04/CMakeLists.txt
new file mode 100644
index 0000000..4d596e0
--- /dev/null
+++ b/hw04/CMakeLists.txt
@@ -0,0 +1,58 @@
+cmake_minimum_required(VERSION 3.19)
+project(OpenGL_Example)
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_PREFIX_PATH "C:/Qt/Qt5.12.10/5.12.10/mingw73_64/lib/cmake")
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTORCC ON)
+set(CMAKE_AUTOUIC ON)
+
+set(QT_VERSION 5)
+set(REQUIRED_LIBS Core Gui Widgets)
+set(REQUIRED_LIBS_QUALIFIED Qt5::Core Qt5::Gui Qt5::Widgets)
+
+find_package(OpenGL REQUIRED)
+include_directories( ${OPENGL_INCLUDE_DIRS} )
+add_executable(OpenGL_Example
+        main.cpp
+        mainwindow.cpp
+        mainwindow.h
+        oglwidget.cpp
+        oglwidget.h)
+
+if (NOT CMAKE_PREFIX_PATH)
+    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
+            "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
+endif ()
+
+find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
+target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
+if (WIN32)
+    set(DEBUG_SUFFIX)
+    if (CMAKE_BUILD_TYPE MATCHES "Debug")
+        set(DEBUG_SUFFIX "d")
+    endif ()
+    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
+    if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        endif ()
+    endif ()
+    if (EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E make_directory
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+    endif ()
+    foreach (QT_LIB ${REQUIRED_LIBS})
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
+    endforeach (QT_LIB)
+endif ()

diff --git a/hw04/CMakeLists.txt b/hw04/CMakeLists.txt
new file mode 100644
index 0000000..4d596e0
--- /dev/null
+++ b/hw04/CMakeLists.txt
@@ -0,0 +1,58 @@
+cmake_minimum_required(VERSION 3.19)
+project(OpenGL_Example)
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_PREFIX_PATH "C:/Qt/Qt5.12.10/5.12.10/mingw73_64/lib/cmake")
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTORCC ON)
+set(CMAKE_AUTOUIC ON)
+
+set(QT_VERSION 5)
+set(REQUIRED_LIBS Core Gui Widgets)
+set(REQUIRED_LIBS_QUALIFIED Qt5::Core Qt5::Gui Qt5::Widgets)
+
+find_package(OpenGL REQUIRED)
+include_directories( ${OPENGL_INCLUDE_DIRS} )
+add_executable(OpenGL_Example
+        main.cpp
+        mainwindow.cpp
+        mainwindow.h
+        oglwidget.cpp
+        oglwidget.h)
+
+if (NOT CMAKE_PREFIX_PATH)
+    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
+            "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
+endif ()
+
+find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
+target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
+if (WIN32)
+    set(DEBUG_SUFFIX)
+    if (CMAKE_BUILD_TYPE MATCHES "Debug")
+        set(DEBUG_SUFFIX "d")
+    endif ()
+    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
+    if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        endif ()
+    endif ()
+    if (EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E make_directory
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+    endif ()
+    foreach (QT_LIB ${REQUIRED_LIBS})
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
+    endforeach (QT_LIB)
+endif ()
diff --git a/hw04/OpenGL_Example.pro b/hw04/OpenGL_Example.pro
new file mode 100644
index 0000000..edf9575
--- /dev/null
+++ b/hw04/OpenGL_Example.pro
@@ -0,0 +1,27 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#-------------------------------------------------
+#
+# Project created by QtCreator 2016-03-04T23:07:51
+#
+#-------------------------------------------------
+
+QT       += core gui opengl
+
+LIBS    += -lOpengl32
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = opengl1
+TEMPLATE = app
+
+
+SOURCES += main.cpp\
+        mainwindow.cpp \
+    oglwidget.cpp
+
+HEADERS  += mainwindow.h \
+    oglwidget.h
+
+FORMS    += mainwindow.ui

diff --git a/hw04/CMakeLists.txt b/hw04/CMakeLists.txt
new file mode 100644
index 0000000..4d596e0
--- /dev/null
+++ b/hw04/CMakeLists.txt
@@ -0,0 +1,58 @@
+cmake_minimum_required(VERSION 3.19)
+project(OpenGL_Example)
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_PREFIX_PATH "C:/Qt/Qt5.12.10/5.12.10/mingw73_64/lib/cmake")
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTORCC ON)
+set(CMAKE_AUTOUIC ON)
+
+set(QT_VERSION 5)
+set(REQUIRED_LIBS Core Gui Widgets)
+set(REQUIRED_LIBS_QUALIFIED Qt5::Core Qt5::Gui Qt5::Widgets)
+
+find_package(OpenGL REQUIRED)
+include_directories( ${OPENGL_INCLUDE_DIRS} )
+add_executable(OpenGL_Example
+        main.cpp
+        mainwindow.cpp
+        mainwindow.h
+        oglwidget.cpp
+        oglwidget.h)
+
+if (NOT CMAKE_PREFIX_PATH)
+    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
+            "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
+endif ()
+
+find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
+target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
+if (WIN32)
+    set(DEBUG_SUFFIX)
+    if (CMAKE_BUILD_TYPE MATCHES "Debug")
+        set(DEBUG_SUFFIX "d")
+    endif ()
+    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
+    if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        endif ()
+    endif ()
+    if (EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E make_directory
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+    endif ()
+    foreach (QT_LIB ${REQUIRED_LIBS})
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
+    endforeach (QT_LIB)
+endif ()
diff --git a/hw04/OpenGL_Example.pro b/hw04/OpenGL_Example.pro
new file mode 100644
index 0000000..edf9575
--- /dev/null
+++ b/hw04/OpenGL_Example.pro
@@ -0,0 +1,27 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#-------------------------------------------------
+#
+# Project created by QtCreator 2016-03-04T23:07:51
+#
+#-------------------------------------------------
+
+QT       += core gui opengl
+
+LIBS    += -lOpengl32
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = opengl1
+TEMPLATE = app
+
+
+SOURCES += main.cpp\
+        mainwindow.cpp \
+    oglwidget.cpp
+
+HEADERS  += mainwindow.h \
+    oglwidget.h
+
+FORMS    += mainwindow.ui
diff --git a/hw04/main.cpp b/hw04/main.cpp
new file mode 100644
index 0000000..515e368
--- /dev/null
+++ b/hw04/main.cpp
@@ -0,0 +1,14 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    MainWindow w;
+    w.show();
+
+    return a.exec();
+}

diff --git a/hw04/CMakeLists.txt b/hw04/CMakeLists.txt
new file mode 100644
index 0000000..4d596e0
--- /dev/null
+++ b/hw04/CMakeLists.txt
@@ -0,0 +1,58 @@
+cmake_minimum_required(VERSION 3.19)
+project(OpenGL_Example)
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_PREFIX_PATH "C:/Qt/Qt5.12.10/5.12.10/mingw73_64/lib/cmake")
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTORCC ON)
+set(CMAKE_AUTOUIC ON)
+
+set(QT_VERSION 5)
+set(REQUIRED_LIBS Core Gui Widgets)
+set(REQUIRED_LIBS_QUALIFIED Qt5::Core Qt5::Gui Qt5::Widgets)
+
+find_package(OpenGL REQUIRED)
+include_directories( ${OPENGL_INCLUDE_DIRS} )
+add_executable(OpenGL_Example
+        main.cpp
+        mainwindow.cpp
+        mainwindow.h
+        oglwidget.cpp
+        oglwidget.h)
+
+if (NOT CMAKE_PREFIX_PATH)
+    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
+            "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
+endif ()
+
+find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
+target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
+if (WIN32)
+    set(DEBUG_SUFFIX)
+    if (CMAKE_BUILD_TYPE MATCHES "Debug")
+        set(DEBUG_SUFFIX "d")
+    endif ()
+    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
+    if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        endif ()
+    endif ()
+    if (EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E make_directory
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+    endif ()
+    foreach (QT_LIB ${REQUIRED_LIBS})
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
+    endforeach (QT_LIB)
+endif ()
diff --git a/hw04/OpenGL_Example.pro b/hw04/OpenGL_Example.pro
new file mode 100644
index 0000000..edf9575
--- /dev/null
+++ b/hw04/OpenGL_Example.pro
@@ -0,0 +1,27 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#-------------------------------------------------
+#
+# Project created by QtCreator 2016-03-04T23:07:51
+#
+#-------------------------------------------------
+
+QT       += core gui opengl
+
+LIBS    += -lOpengl32
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = opengl1
+TEMPLATE = app
+
+
+SOURCES += main.cpp\
+        mainwindow.cpp \
+    oglwidget.cpp
+
+HEADERS  += mainwindow.h \
+    oglwidget.h
+
+FORMS    += mainwindow.ui
diff --git a/hw04/main.cpp b/hw04/main.cpp
new file mode 100644
index 0000000..515e368
--- /dev/null
+++ b/hw04/main.cpp
@@ -0,0 +1,14 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    MainWindow w;
+    w.show();
+
+    return a.exec();
+}
diff --git a/hw04/mainwindow.cpp b/hw04/mainwindow.cpp
new file mode 100644
index 0000000..ff258c4
--- /dev/null
+++ b/hw04/mainwindow.cpp
@@ -0,0 +1,17 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+
+MainWindow::MainWindow(QWidget *parent) :
+    QMainWindow(parent),
+    ui(new Ui::MainWindow)
+{
+    ui->setupUi(this);
+}
+
+MainWindow::~MainWindow()
+{
+    delete ui;
+}

diff --git a/hw04/CMakeLists.txt b/hw04/CMakeLists.txt
new file mode 100644
index 0000000..4d596e0
--- /dev/null
+++ b/hw04/CMakeLists.txt
@@ -0,0 +1,58 @@
+cmake_minimum_required(VERSION 3.19)
+project(OpenGL_Example)
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_PREFIX_PATH "C:/Qt/Qt5.12.10/5.12.10/mingw73_64/lib/cmake")
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTORCC ON)
+set(CMAKE_AUTOUIC ON)
+
+set(QT_VERSION 5)
+set(REQUIRED_LIBS Core Gui Widgets)
+set(REQUIRED_LIBS_QUALIFIED Qt5::Core Qt5::Gui Qt5::Widgets)
+
+find_package(OpenGL REQUIRED)
+include_directories( ${OPENGL_INCLUDE_DIRS} )
+add_executable(OpenGL_Example
+        main.cpp
+        mainwindow.cpp
+        mainwindow.h
+        oglwidget.cpp
+        oglwidget.h)
+
+if (NOT CMAKE_PREFIX_PATH)
+    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
+            "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
+endif ()
+
+find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
+target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
+if (WIN32)
+    set(DEBUG_SUFFIX)
+    if (CMAKE_BUILD_TYPE MATCHES "Debug")
+        set(DEBUG_SUFFIX "d")
+    endif ()
+    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
+    if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        endif ()
+    endif ()
+    if (EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E make_directory
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+    endif ()
+    foreach (QT_LIB ${REQUIRED_LIBS})
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
+    endforeach (QT_LIB)
+endif ()
diff --git a/hw04/OpenGL_Example.pro b/hw04/OpenGL_Example.pro
new file mode 100644
index 0000000..edf9575
--- /dev/null
+++ b/hw04/OpenGL_Example.pro
@@ -0,0 +1,27 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#-------------------------------------------------
+#
+# Project created by QtCreator 2016-03-04T23:07:51
+#
+#-------------------------------------------------
+
+QT       += core gui opengl
+
+LIBS    += -lOpengl32
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = opengl1
+TEMPLATE = app
+
+
+SOURCES += main.cpp\
+        mainwindow.cpp \
+    oglwidget.cpp
+
+HEADERS  += mainwindow.h \
+    oglwidget.h
+
+FORMS    += mainwindow.ui
diff --git a/hw04/main.cpp b/hw04/main.cpp
new file mode 100644
index 0000000..515e368
--- /dev/null
+++ b/hw04/main.cpp
@@ -0,0 +1,14 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    MainWindow w;
+    w.show();
+
+    return a.exec();
+}
diff --git a/hw04/mainwindow.cpp b/hw04/mainwindow.cpp
new file mode 100644
index 0000000..ff258c4
--- /dev/null
+++ b/hw04/mainwindow.cpp
@@ -0,0 +1,17 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+
+MainWindow::MainWindow(QWidget *parent) :
+    QMainWindow(parent),
+    ui(new Ui::MainWindow)
+{
+    ui->setupUi(this);
+}
+
+MainWindow::~MainWindow()
+{
+    delete ui;
+}
diff --git a/hw04/mainwindow.h b/hw04/mainwindow.h
new file mode 100644
index 0000000..b3aab25
--- /dev/null
+++ b/hw04/mainwindow.h
@@ -0,0 +1,25 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QMainWindow>
+
+namespace Ui {
+class MainWindow;
+}
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit MainWindow(QWidget *parent = 0);
+    ~MainWindow();
+
+private:
+    Ui::MainWindow *ui;
+};
+
+#endif // MAINWINDOW_H

diff --git a/hw04/CMakeLists.txt b/hw04/CMakeLists.txt
new file mode 100644
index 0000000..4d596e0
--- /dev/null
+++ b/hw04/CMakeLists.txt
@@ -0,0 +1,58 @@
+cmake_minimum_required(VERSION 3.19)
+project(OpenGL_Example)
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_PREFIX_PATH "C:/Qt/Qt5.12.10/5.12.10/mingw73_64/lib/cmake")
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTORCC ON)
+set(CMAKE_AUTOUIC ON)
+
+set(QT_VERSION 5)
+set(REQUIRED_LIBS Core Gui Widgets)
+set(REQUIRED_LIBS_QUALIFIED Qt5::Core Qt5::Gui Qt5::Widgets)
+
+find_package(OpenGL REQUIRED)
+include_directories( ${OPENGL_INCLUDE_DIRS} )
+add_executable(OpenGL_Example
+        main.cpp
+        mainwindow.cpp
+        mainwindow.h
+        oglwidget.cpp
+        oglwidget.h)
+
+if (NOT CMAKE_PREFIX_PATH)
+    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
+            "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
+endif ()
+
+find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
+target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
+if (WIN32)
+    set(DEBUG_SUFFIX)
+    if (CMAKE_BUILD_TYPE MATCHES "Debug")
+        set(DEBUG_SUFFIX "d")
+    endif ()
+    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
+    if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        endif ()
+    endif ()
+    if (EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E make_directory
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+    endif ()
+    foreach (QT_LIB ${REQUIRED_LIBS})
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
+    endforeach (QT_LIB)
+endif ()
diff --git a/hw04/OpenGL_Example.pro b/hw04/OpenGL_Example.pro
new file mode 100644
index 0000000..edf9575
--- /dev/null
+++ b/hw04/OpenGL_Example.pro
@@ -0,0 +1,27 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#-------------------------------------------------
+#
+# Project created by QtCreator 2016-03-04T23:07:51
+#
+#-------------------------------------------------
+
+QT       += core gui opengl
+
+LIBS    += -lOpengl32
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = opengl1
+TEMPLATE = app
+
+
+SOURCES += main.cpp\
+        mainwindow.cpp \
+    oglwidget.cpp
+
+HEADERS  += mainwindow.h \
+    oglwidget.h
+
+FORMS    += mainwindow.ui
diff --git a/hw04/main.cpp b/hw04/main.cpp
new file mode 100644
index 0000000..515e368
--- /dev/null
+++ b/hw04/main.cpp
@@ -0,0 +1,14 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    MainWindow w;
+    w.show();
+
+    return a.exec();
+}
diff --git a/hw04/mainwindow.cpp b/hw04/mainwindow.cpp
new file mode 100644
index 0000000..ff258c4
--- /dev/null
+++ b/hw04/mainwindow.cpp
@@ -0,0 +1,17 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+
+MainWindow::MainWindow(QWidget *parent) :
+    QMainWindow(parent),
+    ui(new Ui::MainWindow)
+{
+    ui->setupUi(this);
+}
+
+MainWindow::~MainWindow()
+{
+    delete ui;
+}
diff --git a/hw04/mainwindow.h b/hw04/mainwindow.h
new file mode 100644
index 0000000..b3aab25
--- /dev/null
+++ b/hw04/mainwindow.h
@@ -0,0 +1,25 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QMainWindow>
+
+namespace Ui {
+class MainWindow;
+}
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit MainWindow(QWidget *parent = 0);
+    ~MainWindow();
+
+private:
+    Ui::MainWindow *ui;
+};
+
+#endif // MAINWINDOW_H
diff --git a/hw04/mainwindow.ui b/hw04/mainwindow.ui
new file mode 100644
index 0000000..5e1745e
--- /dev/null
+++ b/hw04/mainwindow.ui
@@ -0,0 +1,64 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QMainWindow" name="MainWindow">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>548</width>
+    <height>415</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>MainWindow</string>
+  </property>
+  <widget class="QWidget" name="centralWidget">
+   <layout class="QVBoxLayout" name="verticalLayout">
+    <item>
+     <widget class="OGLWidget" name="glwidget">
+      <property name="sizePolicy">
+       <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+        <horstretch>0</horstretch>
+        <verstretch>0</verstretch>
+       </sizepolicy>
+      </property>
+     </widget>
+    </item>
+   </layout>
+  </widget>
+  <widget class="QMenuBar" name="menuBar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>548</width>
+     <height>21</height>
+    </rect>
+   </property>
+  </widget>
+  <widget class="QToolBar" name="mainToolBar">
+   <attribute name="toolBarArea">
+    <enum>TopToolBarArea</enum>
+   </attribute>
+   <attribute name="toolBarBreak">
+    <bool>false</bool>
+   </attribute>
+  </widget>
+  <widget class="QStatusBar" name="statusBar"/>
+ </widget>
+ <layoutdefault spacing="6" margin="11"/>
+ <customwidgets>
+  <customwidget>
+   <class>OGLWidget</class>
+   <extends>QOpenGLWidget</extends>
+   <header>oglwidget.h</header>
+   <slots>
+    <slot>setParamA(double)</slot>
+    <slot>setParamB(double)</slot>
+   </slots>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>

diff --git a/hw04/CMakeLists.txt b/hw04/CMakeLists.txt
new file mode 100644
index 0000000..4d596e0
--- /dev/null
+++ b/hw04/CMakeLists.txt
@@ -0,0 +1,58 @@
+cmake_minimum_required(VERSION 3.19)
+project(OpenGL_Example)
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_PREFIX_PATH "C:/Qt/Qt5.12.10/5.12.10/mingw73_64/lib/cmake")
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTORCC ON)
+set(CMAKE_AUTOUIC ON)
+
+set(QT_VERSION 5)
+set(REQUIRED_LIBS Core Gui Widgets)
+set(REQUIRED_LIBS_QUALIFIED Qt5::Core Qt5::Gui Qt5::Widgets)
+
+find_package(OpenGL REQUIRED)
+include_directories( ${OPENGL_INCLUDE_DIRS} )
+add_executable(OpenGL_Example
+        main.cpp
+        mainwindow.cpp
+        mainwindow.h
+        oglwidget.cpp
+        oglwidget.h)
+
+if (NOT CMAKE_PREFIX_PATH)
+    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
+            "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
+endif ()
+
+find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
+target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
+if (WIN32)
+    set(DEBUG_SUFFIX)
+    if (CMAKE_BUILD_TYPE MATCHES "Debug")
+        set(DEBUG_SUFFIX "d")
+    endif ()
+    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
+    if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        endif ()
+    endif ()
+    if (EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E make_directory
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+    endif ()
+    foreach (QT_LIB ${REQUIRED_LIBS})
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
+    endforeach (QT_LIB)
+endif ()
diff --git a/hw04/OpenGL_Example.pro b/hw04/OpenGL_Example.pro
new file mode 100644
index 0000000..edf9575
--- /dev/null
+++ b/hw04/OpenGL_Example.pro
@@ -0,0 +1,27 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#-------------------------------------------------
+#
+# Project created by QtCreator 2016-03-04T23:07:51
+#
+#-------------------------------------------------
+
+QT       += core gui opengl
+
+LIBS    += -lOpengl32
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = opengl1
+TEMPLATE = app
+
+
+SOURCES += main.cpp\
+        mainwindow.cpp \
+    oglwidget.cpp
+
+HEADERS  += mainwindow.h \
+    oglwidget.h
+
+FORMS    += mainwindow.ui
diff --git a/hw04/main.cpp b/hw04/main.cpp
new file mode 100644
index 0000000..515e368
--- /dev/null
+++ b/hw04/main.cpp
@@ -0,0 +1,14 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    MainWindow w;
+    w.show();
+
+    return a.exec();
+}
diff --git a/hw04/mainwindow.cpp b/hw04/mainwindow.cpp
new file mode 100644
index 0000000..ff258c4
--- /dev/null
+++ b/hw04/mainwindow.cpp
@@ -0,0 +1,17 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+
+MainWindow::MainWindow(QWidget *parent) :
+    QMainWindow(parent),
+    ui(new Ui::MainWindow)
+{
+    ui->setupUi(this);
+}
+
+MainWindow::~MainWindow()
+{
+    delete ui;
+}
diff --git a/hw04/mainwindow.h b/hw04/mainwindow.h
new file mode 100644
index 0000000..b3aab25
--- /dev/null
+++ b/hw04/mainwindow.h
@@ -0,0 +1,25 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QMainWindow>
+
+namespace Ui {
+class MainWindow;
+}
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit MainWindow(QWidget *parent = 0);
+    ~MainWindow();
+
+private:
+    Ui::MainWindow *ui;
+};
+
+#endif // MAINWINDOW_H
diff --git a/hw04/mainwindow.ui b/hw04/mainwindow.ui
new file mode 100644
index 0000000..5e1745e
--- /dev/null
+++ b/hw04/mainwindow.ui
@@ -0,0 +1,64 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QMainWindow" name="MainWindow">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>548</width>
+    <height>415</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>MainWindow</string>
+  </property>
+  <widget class="QWidget" name="centralWidget">
+   <layout class="QVBoxLayout" name="verticalLayout">
+    <item>
+     <widget class="OGLWidget" name="glwidget">
+      <property name="sizePolicy">
+       <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+        <horstretch>0</horstretch>
+        <verstretch>0</verstretch>
+       </sizepolicy>
+      </property>
+     </widget>
+    </item>
+   </layout>
+  </widget>
+  <widget class="QMenuBar" name="menuBar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>548</width>
+     <height>21</height>
+    </rect>
+   </property>
+  </widget>
+  <widget class="QToolBar" name="mainToolBar">
+   <attribute name="toolBarArea">
+    <enum>TopToolBarArea</enum>
+   </attribute>
+   <attribute name="toolBarBreak">
+    <bool>false</bool>
+   </attribute>
+  </widget>
+  <widget class="QStatusBar" name="statusBar"/>
+ </widget>
+ <layoutdefault spacing="6" margin="11"/>
+ <customwidgets>
+  <customwidget>
+   <class>OGLWidget</class>
+   <extends>QOpenGLWidget</extends>
+   <header>oglwidget.h</header>
+   <slots>
+    <slot>setParamA(double)</slot>
+    <slot>setParamB(double)</slot>
+   </slots>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>
diff --git a/hw04/mesh1.obj b/hw04/mesh1.obj
new file mode 100644
index 0000000..0af35e5
--- /dev/null
+++ b/hw04/mesh1.obj
@@ -0,0 +1,8 @@
+v  0  0  0
+v  8  0  0
+v  0  8  0
+v  0  0  8
+f  1 2 4
+f  2 3 4
+f  3 1 4
+f  3 2 1
\ No newline at end of file

diff --git a/hw04/CMakeLists.txt b/hw04/CMakeLists.txt
new file mode 100644
index 0000000..4d596e0
--- /dev/null
+++ b/hw04/CMakeLists.txt
@@ -0,0 +1,58 @@
+cmake_minimum_required(VERSION 3.19)
+project(OpenGL_Example)
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_PREFIX_PATH "C:/Qt/Qt5.12.10/5.12.10/mingw73_64/lib/cmake")
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTORCC ON)
+set(CMAKE_AUTOUIC ON)
+
+set(QT_VERSION 5)
+set(REQUIRED_LIBS Core Gui Widgets)
+set(REQUIRED_LIBS_QUALIFIED Qt5::Core Qt5::Gui Qt5::Widgets)
+
+find_package(OpenGL REQUIRED)
+include_directories( ${OPENGL_INCLUDE_DIRS} )
+add_executable(OpenGL_Example
+        main.cpp
+        mainwindow.cpp
+        mainwindow.h
+        oglwidget.cpp
+        oglwidget.h)
+
+if (NOT CMAKE_PREFIX_PATH)
+    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
+            "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
+endif ()
+
+find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
+target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
+if (WIN32)
+    set(DEBUG_SUFFIX)
+    if (CMAKE_BUILD_TYPE MATCHES "Debug")
+        set(DEBUG_SUFFIX "d")
+    endif ()
+    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
+    if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        endif ()
+    endif ()
+    if (EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E make_directory
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+    endif ()
+    foreach (QT_LIB ${REQUIRED_LIBS})
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
+    endforeach (QT_LIB)
+endif ()
diff --git a/hw04/OpenGL_Example.pro b/hw04/OpenGL_Example.pro
new file mode 100644
index 0000000..edf9575
--- /dev/null
+++ b/hw04/OpenGL_Example.pro
@@ -0,0 +1,27 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#-------------------------------------------------
+#
+# Project created by QtCreator 2016-03-04T23:07:51
+#
+#-------------------------------------------------
+
+QT       += core gui opengl
+
+LIBS    += -lOpengl32
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = opengl1
+TEMPLATE = app
+
+
+SOURCES += main.cpp\
+        mainwindow.cpp \
+    oglwidget.cpp
+
+HEADERS  += mainwindow.h \
+    oglwidget.h
+
+FORMS    += mainwindow.ui
diff --git a/hw04/main.cpp b/hw04/main.cpp
new file mode 100644
index 0000000..515e368
--- /dev/null
+++ b/hw04/main.cpp
@@ -0,0 +1,14 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    MainWindow w;
+    w.show();
+
+    return a.exec();
+}
diff --git a/hw04/mainwindow.cpp b/hw04/mainwindow.cpp
new file mode 100644
index 0000000..ff258c4
--- /dev/null
+++ b/hw04/mainwindow.cpp
@@ -0,0 +1,17 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+
+MainWindow::MainWindow(QWidget *parent) :
+    QMainWindow(parent),
+    ui(new Ui::MainWindow)
+{
+    ui->setupUi(this);
+}
+
+MainWindow::~MainWindow()
+{
+    delete ui;
+}
diff --git a/hw04/mainwindow.h b/hw04/mainwindow.h
new file mode 100644
index 0000000..b3aab25
--- /dev/null
+++ b/hw04/mainwindow.h
@@ -0,0 +1,25 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QMainWindow>
+
+namespace Ui {
+class MainWindow;
+}
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit MainWindow(QWidget *parent = 0);
+    ~MainWindow();
+
+private:
+    Ui::MainWindow *ui;
+};
+
+#endif // MAINWINDOW_H
diff --git a/hw04/mainwindow.ui b/hw04/mainwindow.ui
new file mode 100644
index 0000000..5e1745e
--- /dev/null
+++ b/hw04/mainwindow.ui
@@ -0,0 +1,64 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QMainWindow" name="MainWindow">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>548</width>
+    <height>415</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>MainWindow</string>
+  </property>
+  <widget class="QWidget" name="centralWidget">
+   <layout class="QVBoxLayout" name="verticalLayout">
+    <item>
+     <widget class="OGLWidget" name="glwidget">
+      <property name="sizePolicy">
+       <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+        <horstretch>0</horstretch>
+        <verstretch>0</verstretch>
+       </sizepolicy>
+      </property>
+     </widget>
+    </item>
+   </layout>
+  </widget>
+  <widget class="QMenuBar" name="menuBar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>548</width>
+     <height>21</height>
+    </rect>
+   </property>
+  </widget>
+  <widget class="QToolBar" name="mainToolBar">
+   <attribute name="toolBarArea">
+    <enum>TopToolBarArea</enum>
+   </attribute>
+   <attribute name="toolBarBreak">
+    <bool>false</bool>
+   </attribute>
+  </widget>
+  <widget class="QStatusBar" name="statusBar"/>
+ </widget>
+ <layoutdefault spacing="6" margin="11"/>
+ <customwidgets>
+  <customwidget>
+   <class>OGLWidget</class>
+   <extends>QOpenGLWidget</extends>
+   <header>oglwidget.h</header>
+   <slots>
+    <slot>setParamA(double)</slot>
+    <slot>setParamB(double)</slot>
+   </slots>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>
diff --git a/hw04/mesh1.obj b/hw04/mesh1.obj
new file mode 100644
index 0000000..0af35e5
--- /dev/null
+++ b/hw04/mesh1.obj
@@ -0,0 +1,8 @@
+v  0  0  0
+v  8  0  0
+v  0  8  0
+v  0  0  8
+f  1 2 4
+f  2 3 4
+f  3 1 4
+f  3 2 1
\ No newline at end of file
diff --git a/hw04/oglwidget.cpp b/hw04/oglwidget.cpp
new file mode 100644
index 0000000..3be1f28
--- /dev/null
+++ b/hw04/oglwidget.cpp
@@ -0,0 +1,404 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "oglwidget.h"
+#include <math.h>
+#include <iostream>
+#include <iomanip>
+#include <fstream>
+#include <string>
+#include <vector>
+
+#define PI 3.14159265358979323846
+using namespace std;
+
+static double alpha = 45.0; // rotation angle
+
+class Vertex{
+public:
+    float p[3]; // coordinates
+
+    Vertex();
+    Vertex( float point[3]);
+    Vertex( float x, float y, float z);
+    void Print() {
+        cout << p[0] << " " << p[1] << " " << p[2] << endl;
+    }
+    // print coordinates on screen
+
+};
+
+Vertex::Vertex(){}; // empty constructor
+
+Vertex::Vertex(float x, float y, float z){ // constructor with initialization
+    p[0] = x;
+    p[1] = y;
+    p[2] = z;
+}
+
+Vertex::Vertex(float *point) {
+    copy_n(point, 3, p);
+}
+
+Vertex operator+( Vertex a, Vertex b) // add pts or vectors
+{
+    return *new Vertex(a.p[0] + b.p[0], a.p[1] + b.p[1],a.p[2] + b.p[2]);
+}
+Vertex operator-( Vertex a, Vertex b)// subtract pts or vectors
+{
+    return *new Vertex(a.p[0] - b.p[0], a.p[1] - b.p[1],a.p[2] - b.p[2]);
+}
+Vertex operator*( float a, Vertex b) // product between scalar and vector
+{
+    return *new Vertex(a*b.p[0], a*b.p[1], a*b.p[2]);
+}
+float operator*( Vertex a, Vertex b) // scalar product
+{
+    return a.p[0] * b.p[0] + a.p[1] * b.p[1] + a.p[2] * b.p[2];
+}
+Vertex operator%( Vertex a, Vertex b) // cross product
+{
+    return *new Vertex(a.p[1]*b.p[2] - a.p[2]*b.p[1], a.p[2]*b.p[0] - a.p[0]*b.p[2], a.p[0]*b.p[1] - a.p[1]*b.p[0]);
+}
+bool operator==(Vertex a, Vertex b) // check if coords are the same
+{
+    return (a.p[0] == b.p[0]) && (a.p[1] == b.p[1]) && (a.p[2] == b.p[2]);
+}
+
+class Tri
+{
+public:
+    int iv[3]; // vertex indices
+    int it[3]; // adjacent triangle indices
+    int ie[3]; // edge vertex indices
+    Tri();
+    Tri( int i[3]);
+    Tri( int i, int j, int k);
+    void Print();
+};
+
+void subDivEdgeMidpoint();
+
+void saveData();
+
+Tri::Tri() {
+    it[0] = -1;
+    it[1] = -1;
+    it[2] = -1;
+}
+
+Tri::Tri(int *i) {
+    new (this) Tri();
+
+}
+
+Tri::Tri(int i, int j, int k) {
+    new (this) Tri();
+
+    iv[0] = i;
+    iv[1] = j;
+    iv[2] = k;
+}
+
+
+vector <Vertex> pts;
+vector <int> valences;  // valence list (no. of triangles for every point
+vector <Tri> tris;
+
+void Tri::Print() {
+    cout << "Tri:" << endl << " neighbour: " << it[0] << " " << it[1] << " " << it[2] << endl << " - ";
+    cout << valences[iv[0]] << "x ";
+    pts[iv[0]].Print();
+    cout << " - " << valences[iv[1]] << "x ";
+    pts[iv[1]].Print();
+    cout << " - " << valences[iv[2]] << "x ";
+    pts[iv[2]].Print();
+    cout << endl;
+}
+
+
+void loadData()
+{
+    string fname = R"(C:\CLionProjects\cg\hw04\mesh1.obj)";
+    ifstream file( fname);
+    if (!file){
+        cout << "error opening file" << endl;
+        return;
+    }
+    string key;
+    while( file){
+        //getline( file, line);
+        file >> key;
+        if (key == "v") {
+            float x, y, z;
+            file >> x >> y >> z;
+            Vertex pVertex = *new Vertex(x, y, z);
+            pts.push_back(pVertex);
+            valences.push_back(0);
+        } else if (key == "f") {
+            int a, b, c;
+            file >> a >> b >> c;
+            Tri pTriangle = *new Tri(a-1, b-1, c-1);
+            tris.push_back(pTriangle);
+        }
+    }
+    file.close();
+
+    tris.pop_back();
+
+    subDivEdgeMidpoint();
+    subDivEdgeMidpoint();
+
+    // Connectivity Algorithm
+    for (int i = 0; i < tris.size(); ++i) {
+        Tri triag = tris[i];
+        int n = 0;
+        // Search for neighbour
+        for (int ti = 0; ti < tris.size(); ++ti) {
+            if (i == ti) continue;
+            Tri t = tris[ti];
+            int count = 0;
+            for (int x : triag.iv) {
+                for (int y : t.iv) {
+                    if (x == y)
+                        count++;
+                }
+            }
+            // if two points are the same, they are neighbours
+            if (count == 2)
+                triag.it[n++] = ti;
+        }
+
+        // increase valence for each vertex of triangle
+        valences[triag.iv[0]]++;
+        valences[triag.iv[1]]++;
+        valences[triag.iv[2]]++;
+
+        tris[i] = triag;
+    }
+
+    for (auto triag : tris) {
+        triag.Print();
+    }
+
+
+//    saveData();
+}
+
+void saveData() {
+    string fname = R"(C:\CLionProjects\cg\hw04\test2.obj)";
+    ofstream file( fname);
+    if (!file){
+        cout << "error opening file" << endl;
+        return;
+    }
+
+    for (auto vert : pts) {
+        file << "v\t" << vert.p[0] << "\t" << vert.p[1] << "\t" << vert.p[2] << endl;
+    }
+
+    for (auto triag : tris) {
+        file << "f\t" << triag.iv[0]+1 << "\t" << triag.iv[1]+1 << "\t" << triag.iv[2]+1 << endl;
+    }
+
+    file.close();
+}
+
+
+void subDivEdgeMidpoint() {
+    const unsigned long long int amountToSubDiv = tris.size();
+    for (int i = 0; i < amountToSubDiv; ++i) {
+        Tri triag = tris[i];
+
+        Vertex a = pts[triag.iv[0]];
+        Vertex b = pts[triag.iv[1]];
+        Vertex c = pts[triag.iv[2]];
+
+//        int e = pts.size();
+        int ei0 = -1;
+        int ei1 = -1;
+        int ei2 = -1;
+        Vertex e0 = 0.5f * (a+b);
+        Vertex e1 = 0.5f * (c+b);
+        Vertex e2 = 0.5f * (a+c);
+        for (int j = 0; j < pts.size(); ++j) {
+            if (pts[j] == e0)
+                ei0 = j;
+            if (pts[j] == e1)
+                ei1 = j;
+            if (pts[j] == e2)
+                ei2 = j;
+        }
+        if (ei0 == -1) {
+            ei0 = pts.size();
+            pts.push_back(e0);
+            valences.push_back(0);
+        }
+        if (ei1 == -1) {
+            ei1 = pts.size();
+            pts.push_back(e1);
+            valences.push_back(0);
+        }
+        if (ei2 == -1) {
+            ei2 = pts.size();
+            pts.push_back(e2);
+            valences.push_back(0);
+        }
+
+        tris.push_back(*new Tri(triag.iv[2], ei2, ei1));
+        tris.push_back(*new Tri(triag.iv[1], ei0, ei1));
+        tris.push_back(*new Tri(ei0, ei1, ei2));
+
+
+        triag.iv[1] = ei0;
+        triag.iv[2] = ei2;
+        tris[i] = triag;
+    }
+}
+
+void DrawTriag() {
+
+    glPolygonMode(GL_FRONT_AND_BACK , GL_LINE);
+    glBegin( GL_TRIANGLES);
+    for (auto tri : tris) {
+        Vertex a = pts[tri.iv[0]];
+        Vertex b = pts[tri.iv[1]];
+        Vertex c = pts[tri.iv[2]];
+        Vertex nvec = (b-a)%(c-a);
+
+        glNormal3fv(nvec.p);
+
+        glVertex3fv(a.p);
+        glVertex3fv(c.p);
+        glVertex3fv(b.p);
+
+    }
+    glEnd();
+}
+
+// initialize Open GL lighting and projection matrix
+void InitLightingAndProjection() // to be executed once before drawing
+{
+    // light positions and colors
+    GLfloat LightPosition1[4] = { 10, 5, 10,  0};
+    GLfloat LightPosition2[4] = { -5, 5, -10,  0};
+    GLfloat ColorRedish[4] = { 1.0,  .8,  .8,  1}; // white with a little bit of red
+    GLfloat ColorBlueish[4] = { .8,  .8,  1.0,  1};// white with a little bit of blue
+
+    glEnable( GL_DEPTH_TEST); // switch on z-buffer
+    glDepthFunc( GL_LESS);
+
+    glShadeModel( GL_SMOOTH); // Gouraud shading
+    //glShadeModel( GL_FLAT);
+
+    glEnable( GL_LIGHTING); // use lighting
+    glLightModeli( GL_LIGHT_MODEL_TWO_SIDE, 1); // draw both sides
+
+    // define and switch on light 0
+    glLightfv( GL_LIGHT0, GL_POSITION, LightPosition1);
+    glLightfv( GL_LIGHT0, GL_DIFFUSE,  ColorRedish);
+    glLightfv( GL_LIGHT0, GL_SPECULAR, ColorRedish);
+    glEnable( GL_LIGHT0);
+
+    // define and switch on light 1
+    glLightfv( GL_LIGHT1, GL_POSITION, LightPosition2);
+    glLightfv( GL_LIGHT1, GL_DIFFUSE,  ColorBlueish);
+    glLightfv( GL_LIGHT1, GL_SPECULAR, ColorBlueish);
+    glEnable( GL_LIGHT1);
+
+    glMatrixMode( GL_PROJECTION); // define camera projection
+    glLoadIdentity(); // reset matrix to identity (otherwise existing matrix will be multiplied with)
+    glOrtho( -15, 15, -10, 10, -50, 50); // orthogonal projection (xmin xmax ymin ymax zmin zmax)
+    //glFrustum( -10, 10, -8, 8, 2, 20); // perspective projektion
+}
+
+// define material color properties for front and back side
+void SetMaterialColor( int side, float r, float g, float b){
+    float	amb[4], dif[4], spe[4];
+    int	i, mat;
+
+    dif[0] = r; // diffuse color as defined by r,g, and b
+    dif[1] = g;
+    dif[2] = b;
+    for( i=0; i<3; i++){
+        amb[i] = .1 * dif[i]; // ambient color is 10 percent of diffuse
+        spe[i] = .5; // specular color is just white / gray
+    }
+    amb[3] = dif[3] = spe[3] = 1.0; // alpha component is always 1
+    switch( side){
+        case 1:	mat = GL_FRONT; break;
+        case 2:	mat = GL_BACK; break;
+        default: mat = GL_FRONT_AND_BACK; break;
+    }
+    glMaterialfv( mat, GL_AMBIENT, amb); // define ambient, diffuse and specular components
+    glMaterialfv( mat, GL_DIFFUSE, dif);
+    glMaterialfv( mat, GL_SPECULAR, spe);
+    glMaterialf( mat, GL_SHININESS, 50.0); // Phong constant for the size of highlights
+}
+
+
+OGLWidget::OGLWidget(QWidget *parent) // constructor
+    : QOpenGLWidget(parent)
+{
+    // Setup the animation timer to fire every x msec
+    animtimer = new QTimer(this);
+    animtimer->start( 50 );
+
+    // Everytime the timer fires, the animation is going one step forward
+    connect(animtimer, SIGNAL(timeout()), this, SLOT(stepAnimation()));
+
+    animstep = 0;
+}
+
+OGLWidget::~OGLWidget() // destructor
+{
+}
+
+void OGLWidget::stepAnimation()
+{
+    animstep++;    // Increase animation steps
+    update();      // Trigger redraw of scene with paintGL
+}
+
+void OGLWidget::initializeGL() // initializations to be called once
+{
+    initializeOpenGLFunctions();
+
+    InitLightingAndProjection(); // define light sources and projection
+
+    loadData();
+}
+
+void OGLWidget::paintGL() // draw everything, to be called repeatedly
+{
+    glEnable(GL_NORMALIZE); // this is necessary when using glScale (keep normals to unit length)
+
+    // set background color
+    glClearColor(0.8, 0.8, 1.0, 1.0); // bright blue
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+    // draw the scene
+    glMatrixMode( GL_MODELVIEW);
+    glLoadIdentity();				// Reset The Current Modelview Matrix
+    glTranslated( 0 ,0 ,-10.0);     // Move 10 units backwards in z, since camera is at origin
+    glScaled( 2.0, 2.0, 2.0);       // scale objects
+    glRotated( alpha, 0, 3, 1);     // continuous rotation
+    alpha += 2;
+
+    // define color: 1=front, 2=back, 3=both, followed by r, g, and b
+    SetMaterialColor( 1, 0, .2, .2);  // front color is red
+    SetMaterialColor( 2, 0.2, 0.2, 1.0); // back color is blue
+
+    // draw a cylinder with default resolution
+    DrawTriag();
+
+    // make it appear (before this, it's hidden in the rear buffer)
+    glFlush();
+}
+
+void OGLWidget::resizeGL(int w, int h) // called when window size is changed
+{
+    // adjust viewport transform
+    glViewport(0,0,w,h);
+}
+

diff --git a/hw04/CMakeLists.txt b/hw04/CMakeLists.txt
new file mode 100644
index 0000000..4d596e0
--- /dev/null
+++ b/hw04/CMakeLists.txt
@@ -0,0 +1,58 @@
+cmake_minimum_required(VERSION 3.19)
+project(OpenGL_Example)
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_PREFIX_PATH "C:/Qt/Qt5.12.10/5.12.10/mingw73_64/lib/cmake")
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTORCC ON)
+set(CMAKE_AUTOUIC ON)
+
+set(QT_VERSION 5)
+set(REQUIRED_LIBS Core Gui Widgets)
+set(REQUIRED_LIBS_QUALIFIED Qt5::Core Qt5::Gui Qt5::Widgets)
+
+find_package(OpenGL REQUIRED)
+include_directories( ${OPENGL_INCLUDE_DIRS} )
+add_executable(OpenGL_Example
+        main.cpp
+        mainwindow.cpp
+        mainwindow.h
+        oglwidget.cpp
+        oglwidget.h)
+
+if (NOT CMAKE_PREFIX_PATH)
+    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
+            "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
+endif ()
+
+find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
+target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
+if (WIN32)
+    set(DEBUG_SUFFIX)
+    if (CMAKE_BUILD_TYPE MATCHES "Debug")
+        set(DEBUG_SUFFIX "d")
+    endif ()
+    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
+    if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        endif ()
+    endif ()
+    if (EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E make_directory
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+    endif ()
+    foreach (QT_LIB ${REQUIRED_LIBS})
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
+    endforeach (QT_LIB)
+endif ()
diff --git a/hw04/OpenGL_Example.pro b/hw04/OpenGL_Example.pro
new file mode 100644
index 0000000..edf9575
--- /dev/null
+++ b/hw04/OpenGL_Example.pro
@@ -0,0 +1,27 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#-------------------------------------------------
+#
+# Project created by QtCreator 2016-03-04T23:07:51
+#
+#-------------------------------------------------
+
+QT       += core gui opengl
+
+LIBS    += -lOpengl32
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = opengl1
+TEMPLATE = app
+
+
+SOURCES += main.cpp\
+        mainwindow.cpp \
+    oglwidget.cpp
+
+HEADERS  += mainwindow.h \
+    oglwidget.h
+
+FORMS    += mainwindow.ui
diff --git a/hw04/main.cpp b/hw04/main.cpp
new file mode 100644
index 0000000..515e368
--- /dev/null
+++ b/hw04/main.cpp
@@ -0,0 +1,14 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    MainWindow w;
+    w.show();
+
+    return a.exec();
+}
diff --git a/hw04/mainwindow.cpp b/hw04/mainwindow.cpp
new file mode 100644
index 0000000..ff258c4
--- /dev/null
+++ b/hw04/mainwindow.cpp
@@ -0,0 +1,17 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+
+MainWindow::MainWindow(QWidget *parent) :
+    QMainWindow(parent),
+    ui(new Ui::MainWindow)
+{
+    ui->setupUi(this);
+}
+
+MainWindow::~MainWindow()
+{
+    delete ui;
+}
diff --git a/hw04/mainwindow.h b/hw04/mainwindow.h
new file mode 100644
index 0000000..b3aab25
--- /dev/null
+++ b/hw04/mainwindow.h
@@ -0,0 +1,25 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QMainWindow>
+
+namespace Ui {
+class MainWindow;
+}
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit MainWindow(QWidget *parent = 0);
+    ~MainWindow();
+
+private:
+    Ui::MainWindow *ui;
+};
+
+#endif // MAINWINDOW_H
diff --git a/hw04/mainwindow.ui b/hw04/mainwindow.ui
new file mode 100644
index 0000000..5e1745e
--- /dev/null
+++ b/hw04/mainwindow.ui
@@ -0,0 +1,64 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QMainWindow" name="MainWindow">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>548</width>
+    <height>415</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>MainWindow</string>
+  </property>
+  <widget class="QWidget" name="centralWidget">
+   <layout class="QVBoxLayout" name="verticalLayout">
+    <item>
+     <widget class="OGLWidget" name="glwidget">
+      <property name="sizePolicy">
+       <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+        <horstretch>0</horstretch>
+        <verstretch>0</verstretch>
+       </sizepolicy>
+      </property>
+     </widget>
+    </item>
+   </layout>
+  </widget>
+  <widget class="QMenuBar" name="menuBar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>548</width>
+     <height>21</height>
+    </rect>
+   </property>
+  </widget>
+  <widget class="QToolBar" name="mainToolBar">
+   <attribute name="toolBarArea">
+    <enum>TopToolBarArea</enum>
+   </attribute>
+   <attribute name="toolBarBreak">
+    <bool>false</bool>
+   </attribute>
+  </widget>
+  <widget class="QStatusBar" name="statusBar"/>
+ </widget>
+ <layoutdefault spacing="6" margin="11"/>
+ <customwidgets>
+  <customwidget>
+   <class>OGLWidget</class>
+   <extends>QOpenGLWidget</extends>
+   <header>oglwidget.h</header>
+   <slots>
+    <slot>setParamA(double)</slot>
+    <slot>setParamB(double)</slot>
+   </slots>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>
diff --git a/hw04/mesh1.obj b/hw04/mesh1.obj
new file mode 100644
index 0000000..0af35e5
--- /dev/null
+++ b/hw04/mesh1.obj
@@ -0,0 +1,8 @@
+v  0  0  0
+v  8  0  0
+v  0  8  0
+v  0  0  8
+f  1 2 4
+f  2 3 4
+f  3 1 4
+f  3 2 1
\ No newline at end of file
diff --git a/hw04/oglwidget.cpp b/hw04/oglwidget.cpp
new file mode 100644
index 0000000..3be1f28
--- /dev/null
+++ b/hw04/oglwidget.cpp
@@ -0,0 +1,404 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "oglwidget.h"
+#include <math.h>
+#include <iostream>
+#include <iomanip>
+#include <fstream>
+#include <string>
+#include <vector>
+
+#define PI 3.14159265358979323846
+using namespace std;
+
+static double alpha = 45.0; // rotation angle
+
+class Vertex{
+public:
+    float p[3]; // coordinates
+
+    Vertex();
+    Vertex( float point[3]);
+    Vertex( float x, float y, float z);
+    void Print() {
+        cout << p[0] << " " << p[1] << " " << p[2] << endl;
+    }
+    // print coordinates on screen
+
+};
+
+Vertex::Vertex(){}; // empty constructor
+
+Vertex::Vertex(float x, float y, float z){ // constructor with initialization
+    p[0] = x;
+    p[1] = y;
+    p[2] = z;
+}
+
+Vertex::Vertex(float *point) {
+    copy_n(point, 3, p);
+}
+
+Vertex operator+( Vertex a, Vertex b) // add pts or vectors
+{
+    return *new Vertex(a.p[0] + b.p[0], a.p[1] + b.p[1],a.p[2] + b.p[2]);
+}
+Vertex operator-( Vertex a, Vertex b)// subtract pts or vectors
+{
+    return *new Vertex(a.p[0] - b.p[0], a.p[1] - b.p[1],a.p[2] - b.p[2]);
+}
+Vertex operator*( float a, Vertex b) // product between scalar and vector
+{
+    return *new Vertex(a*b.p[0], a*b.p[1], a*b.p[2]);
+}
+float operator*( Vertex a, Vertex b) // scalar product
+{
+    return a.p[0] * b.p[0] + a.p[1] * b.p[1] + a.p[2] * b.p[2];
+}
+Vertex operator%( Vertex a, Vertex b) // cross product
+{
+    return *new Vertex(a.p[1]*b.p[2] - a.p[2]*b.p[1], a.p[2]*b.p[0] - a.p[0]*b.p[2], a.p[0]*b.p[1] - a.p[1]*b.p[0]);
+}
+bool operator==(Vertex a, Vertex b) // check if coords are the same
+{
+    return (a.p[0] == b.p[0]) && (a.p[1] == b.p[1]) && (a.p[2] == b.p[2]);
+}
+
+class Tri
+{
+public:
+    int iv[3]; // vertex indices
+    int it[3]; // adjacent triangle indices
+    int ie[3]; // edge vertex indices
+    Tri();
+    Tri( int i[3]);
+    Tri( int i, int j, int k);
+    void Print();
+};
+
+void subDivEdgeMidpoint();
+
+void saveData();
+
+Tri::Tri() {
+    it[0] = -1;
+    it[1] = -1;
+    it[2] = -1;
+}
+
+Tri::Tri(int *i) {
+    new (this) Tri();
+
+}
+
+Tri::Tri(int i, int j, int k) {
+    new (this) Tri();
+
+    iv[0] = i;
+    iv[1] = j;
+    iv[2] = k;
+}
+
+
+vector <Vertex> pts;
+vector <int> valences;  // valence list (no. of triangles for every point
+vector <Tri> tris;
+
+void Tri::Print() {
+    cout << "Tri:" << endl << " neighbour: " << it[0] << " " << it[1] << " " << it[2] << endl << " - ";
+    cout << valences[iv[0]] << "x ";
+    pts[iv[0]].Print();
+    cout << " - " << valences[iv[1]] << "x ";
+    pts[iv[1]].Print();
+    cout << " - " << valences[iv[2]] << "x ";
+    pts[iv[2]].Print();
+    cout << endl;
+}
+
+
+void loadData()
+{
+    string fname = R"(C:\CLionProjects\cg\hw04\mesh1.obj)";
+    ifstream file( fname);
+    if (!file){
+        cout << "error opening file" << endl;
+        return;
+    }
+    string key;
+    while( file){
+        //getline( file, line);
+        file >> key;
+        if (key == "v") {
+            float x, y, z;
+            file >> x >> y >> z;
+            Vertex pVertex = *new Vertex(x, y, z);
+            pts.push_back(pVertex);
+            valences.push_back(0);
+        } else if (key == "f") {
+            int a, b, c;
+            file >> a >> b >> c;
+            Tri pTriangle = *new Tri(a-1, b-1, c-1);
+            tris.push_back(pTriangle);
+        }
+    }
+    file.close();
+
+    tris.pop_back();
+
+    subDivEdgeMidpoint();
+    subDivEdgeMidpoint();
+
+    // Connectivity Algorithm
+    for (int i = 0; i < tris.size(); ++i) {
+        Tri triag = tris[i];
+        int n = 0;
+        // Search for neighbour
+        for (int ti = 0; ti < tris.size(); ++ti) {
+            if (i == ti) continue;
+            Tri t = tris[ti];
+            int count = 0;
+            for (int x : triag.iv) {
+                for (int y : t.iv) {
+                    if (x == y)
+                        count++;
+                }
+            }
+            // if two points are the same, they are neighbours
+            if (count == 2)
+                triag.it[n++] = ti;
+        }
+
+        // increase valence for each vertex of triangle
+        valences[triag.iv[0]]++;
+        valences[triag.iv[1]]++;
+        valences[triag.iv[2]]++;
+
+        tris[i] = triag;
+    }
+
+    for (auto triag : tris) {
+        triag.Print();
+    }
+
+
+//    saveData();
+}
+
+void saveData() {
+    string fname = R"(C:\CLionProjects\cg\hw04\test2.obj)";
+    ofstream file( fname);
+    if (!file){
+        cout << "error opening file" << endl;
+        return;
+    }
+
+    for (auto vert : pts) {
+        file << "v\t" << vert.p[0] << "\t" << vert.p[1] << "\t" << vert.p[2] << endl;
+    }
+
+    for (auto triag : tris) {
+        file << "f\t" << triag.iv[0]+1 << "\t" << triag.iv[1]+1 << "\t" << triag.iv[2]+1 << endl;
+    }
+
+    file.close();
+}
+
+
+void subDivEdgeMidpoint() {
+    const unsigned long long int amountToSubDiv = tris.size();
+    for (int i = 0; i < amountToSubDiv; ++i) {
+        Tri triag = tris[i];
+
+        Vertex a = pts[triag.iv[0]];
+        Vertex b = pts[triag.iv[1]];
+        Vertex c = pts[triag.iv[2]];
+
+//        int e = pts.size();
+        int ei0 = -1;
+        int ei1 = -1;
+        int ei2 = -1;
+        Vertex e0 = 0.5f * (a+b);
+        Vertex e1 = 0.5f * (c+b);
+        Vertex e2 = 0.5f * (a+c);
+        for (int j = 0; j < pts.size(); ++j) {
+            if (pts[j] == e0)
+                ei0 = j;
+            if (pts[j] == e1)
+                ei1 = j;
+            if (pts[j] == e2)
+                ei2 = j;
+        }
+        if (ei0 == -1) {
+            ei0 = pts.size();
+            pts.push_back(e0);
+            valences.push_back(0);
+        }
+        if (ei1 == -1) {
+            ei1 = pts.size();
+            pts.push_back(e1);
+            valences.push_back(0);
+        }
+        if (ei2 == -1) {
+            ei2 = pts.size();
+            pts.push_back(e2);
+            valences.push_back(0);
+        }
+
+        tris.push_back(*new Tri(triag.iv[2], ei2, ei1));
+        tris.push_back(*new Tri(triag.iv[1], ei0, ei1));
+        tris.push_back(*new Tri(ei0, ei1, ei2));
+
+
+        triag.iv[1] = ei0;
+        triag.iv[2] = ei2;
+        tris[i] = triag;
+    }
+}
+
+void DrawTriag() {
+
+    glPolygonMode(GL_FRONT_AND_BACK , GL_LINE);
+    glBegin( GL_TRIANGLES);
+    for (auto tri : tris) {
+        Vertex a = pts[tri.iv[0]];
+        Vertex b = pts[tri.iv[1]];
+        Vertex c = pts[tri.iv[2]];
+        Vertex nvec = (b-a)%(c-a);
+
+        glNormal3fv(nvec.p);
+
+        glVertex3fv(a.p);
+        glVertex3fv(c.p);
+        glVertex3fv(b.p);
+
+    }
+    glEnd();
+}
+
+// initialize Open GL lighting and projection matrix
+void InitLightingAndProjection() // to be executed once before drawing
+{
+    // light positions and colors
+    GLfloat LightPosition1[4] = { 10, 5, 10,  0};
+    GLfloat LightPosition2[4] = { -5, 5, -10,  0};
+    GLfloat ColorRedish[4] = { 1.0,  .8,  .8,  1}; // white with a little bit of red
+    GLfloat ColorBlueish[4] = { .8,  .8,  1.0,  1};// white with a little bit of blue
+
+    glEnable( GL_DEPTH_TEST); // switch on z-buffer
+    glDepthFunc( GL_LESS);
+
+    glShadeModel( GL_SMOOTH); // Gouraud shading
+    //glShadeModel( GL_FLAT);
+
+    glEnable( GL_LIGHTING); // use lighting
+    glLightModeli( GL_LIGHT_MODEL_TWO_SIDE, 1); // draw both sides
+
+    // define and switch on light 0
+    glLightfv( GL_LIGHT0, GL_POSITION, LightPosition1);
+    glLightfv( GL_LIGHT0, GL_DIFFUSE,  ColorRedish);
+    glLightfv( GL_LIGHT0, GL_SPECULAR, ColorRedish);
+    glEnable( GL_LIGHT0);
+
+    // define and switch on light 1
+    glLightfv( GL_LIGHT1, GL_POSITION, LightPosition2);
+    glLightfv( GL_LIGHT1, GL_DIFFUSE,  ColorBlueish);
+    glLightfv( GL_LIGHT1, GL_SPECULAR, ColorBlueish);
+    glEnable( GL_LIGHT1);
+
+    glMatrixMode( GL_PROJECTION); // define camera projection
+    glLoadIdentity(); // reset matrix to identity (otherwise existing matrix will be multiplied with)
+    glOrtho( -15, 15, -10, 10, -50, 50); // orthogonal projection (xmin xmax ymin ymax zmin zmax)
+    //glFrustum( -10, 10, -8, 8, 2, 20); // perspective projektion
+}
+
+// define material color properties for front and back side
+void SetMaterialColor( int side, float r, float g, float b){
+    float	amb[4], dif[4], spe[4];
+    int	i, mat;
+
+    dif[0] = r; // diffuse color as defined by r,g, and b
+    dif[1] = g;
+    dif[2] = b;
+    for( i=0; i<3; i++){
+        amb[i] = .1 * dif[i]; // ambient color is 10 percent of diffuse
+        spe[i] = .5; // specular color is just white / gray
+    }
+    amb[3] = dif[3] = spe[3] = 1.0; // alpha component is always 1
+    switch( side){
+        case 1:	mat = GL_FRONT; break;
+        case 2:	mat = GL_BACK; break;
+        default: mat = GL_FRONT_AND_BACK; break;
+    }
+    glMaterialfv( mat, GL_AMBIENT, amb); // define ambient, diffuse and specular components
+    glMaterialfv( mat, GL_DIFFUSE, dif);
+    glMaterialfv( mat, GL_SPECULAR, spe);
+    glMaterialf( mat, GL_SHININESS, 50.0); // Phong constant for the size of highlights
+}
+
+
+OGLWidget::OGLWidget(QWidget *parent) // constructor
+    : QOpenGLWidget(parent)
+{
+    // Setup the animation timer to fire every x msec
+    animtimer = new QTimer(this);
+    animtimer->start( 50 );
+
+    // Everytime the timer fires, the animation is going one step forward
+    connect(animtimer, SIGNAL(timeout()), this, SLOT(stepAnimation()));
+
+    animstep = 0;
+}
+
+OGLWidget::~OGLWidget() // destructor
+{
+}
+
+void OGLWidget::stepAnimation()
+{
+    animstep++;    // Increase animation steps
+    update();      // Trigger redraw of scene with paintGL
+}
+
+void OGLWidget::initializeGL() // initializations to be called once
+{
+    initializeOpenGLFunctions();
+
+    InitLightingAndProjection(); // define light sources and projection
+
+    loadData();
+}
+
+void OGLWidget::paintGL() // draw everything, to be called repeatedly
+{
+    glEnable(GL_NORMALIZE); // this is necessary when using glScale (keep normals to unit length)
+
+    // set background color
+    glClearColor(0.8, 0.8, 1.0, 1.0); // bright blue
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+    // draw the scene
+    glMatrixMode( GL_MODELVIEW);
+    glLoadIdentity();				// Reset The Current Modelview Matrix
+    glTranslated( 0 ,0 ,-10.0);     // Move 10 units backwards in z, since camera is at origin
+    glScaled( 2.0, 2.0, 2.0);       // scale objects
+    glRotated( alpha, 0, 3, 1);     // continuous rotation
+    alpha += 2;
+
+    // define color: 1=front, 2=back, 3=both, followed by r, g, and b
+    SetMaterialColor( 1, 0, .2, .2);  // front color is red
+    SetMaterialColor( 2, 0.2, 0.2, 1.0); // back color is blue
+
+    // draw a cylinder with default resolution
+    DrawTriag();
+
+    // make it appear (before this, it's hidden in the rear buffer)
+    glFlush();
+}
+
+void OGLWidget::resizeGL(int w, int h) // called when window size is changed
+{
+    // adjust viewport transform
+    glViewport(0,0,w,h);
+}
+
diff --git a/hw04/oglwidget.h b/hw04/oglwidget.h
new file mode 100644
index 0000000..a536f6a
--- /dev/null
+++ b/hw04/oglwidget.h
@@ -0,0 +1,34 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#ifndef OGLWIDGET_H
+#define OGLWIDGET_H
+
+#include <QOpenGLWidget>
+#include <QOpenGLFunctions>
+#include <QTimer>
+
+class OGLWidget : public QOpenGLWidget,
+                  protected QOpenGLFunctions
+{
+    Q_OBJECT
+
+public:
+    OGLWidget(QWidget *parent = 0);
+    ~OGLWidget();
+
+public slots:
+    void stepAnimation();
+
+protected:
+    void initializeGL();
+    void resizeGL(int w, int h);
+    void paintGL();
+
+protected:
+    QTimer* animtimer; // Timer needed to step animation every x msec
+    int animstep;      // Current animation step (used to rotate triangle
+};
+
+
+#endif // OGLWIDGET_H

diff --git a/hw04/CMakeLists.txt b/hw04/CMakeLists.txt
new file mode 100644
index 0000000..4d596e0
--- /dev/null
+++ b/hw04/CMakeLists.txt
@@ -0,0 +1,58 @@
+cmake_minimum_required(VERSION 3.19)
+project(OpenGL_Example)
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_PREFIX_PATH "C:/Qt/Qt5.12.10/5.12.10/mingw73_64/lib/cmake")
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTORCC ON)
+set(CMAKE_AUTOUIC ON)
+
+set(QT_VERSION 5)
+set(REQUIRED_LIBS Core Gui Widgets)
+set(REQUIRED_LIBS_QUALIFIED Qt5::Core Qt5::Gui Qt5::Widgets)
+
+find_package(OpenGL REQUIRED)
+include_directories( ${OPENGL_INCLUDE_DIRS} )
+add_executable(OpenGL_Example
+        main.cpp
+        mainwindow.cpp
+        mainwindow.h
+        oglwidget.cpp
+        oglwidget.h)
+
+if (NOT CMAKE_PREFIX_PATH)
+    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
+            "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
+endif ()
+
+find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
+target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
+if (WIN32)
+    set(DEBUG_SUFFIX)
+    if (CMAKE_BUILD_TYPE MATCHES "Debug")
+        set(DEBUG_SUFFIX "d")
+    endif ()
+    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
+    if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        endif ()
+    endif ()
+    if (EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E make_directory
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+    endif ()
+    foreach (QT_LIB ${REQUIRED_LIBS})
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
+    endforeach (QT_LIB)
+endif ()
diff --git a/hw04/OpenGL_Example.pro b/hw04/OpenGL_Example.pro
new file mode 100644
index 0000000..edf9575
--- /dev/null
+++ b/hw04/OpenGL_Example.pro
@@ -0,0 +1,27 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#-------------------------------------------------
+#
+# Project created by QtCreator 2016-03-04T23:07:51
+#
+#-------------------------------------------------
+
+QT       += core gui opengl
+
+LIBS    += -lOpengl32
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = opengl1
+TEMPLATE = app
+
+
+SOURCES += main.cpp\
+        mainwindow.cpp \
+    oglwidget.cpp
+
+HEADERS  += mainwindow.h \
+    oglwidget.h
+
+FORMS    += mainwindow.ui
diff --git a/hw04/main.cpp b/hw04/main.cpp
new file mode 100644
index 0000000..515e368
--- /dev/null
+++ b/hw04/main.cpp
@@ -0,0 +1,14 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    MainWindow w;
+    w.show();
+
+    return a.exec();
+}
diff --git a/hw04/mainwindow.cpp b/hw04/mainwindow.cpp
new file mode 100644
index 0000000..ff258c4
--- /dev/null
+++ b/hw04/mainwindow.cpp
@@ -0,0 +1,17 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+
+MainWindow::MainWindow(QWidget *parent) :
+    QMainWindow(parent),
+    ui(new Ui::MainWindow)
+{
+    ui->setupUi(this);
+}
+
+MainWindow::~MainWindow()
+{
+    delete ui;
+}
diff --git a/hw04/mainwindow.h b/hw04/mainwindow.h
new file mode 100644
index 0000000..b3aab25
--- /dev/null
+++ b/hw04/mainwindow.h
@@ -0,0 +1,25 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QMainWindow>
+
+namespace Ui {
+class MainWindow;
+}
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit MainWindow(QWidget *parent = 0);
+    ~MainWindow();
+
+private:
+    Ui::MainWindow *ui;
+};
+
+#endif // MAINWINDOW_H
diff --git a/hw04/mainwindow.ui b/hw04/mainwindow.ui
new file mode 100644
index 0000000..5e1745e
--- /dev/null
+++ b/hw04/mainwindow.ui
@@ -0,0 +1,64 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QMainWindow" name="MainWindow">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>548</width>
+    <height>415</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>MainWindow</string>
+  </property>
+  <widget class="QWidget" name="centralWidget">
+   <layout class="QVBoxLayout" name="verticalLayout">
+    <item>
+     <widget class="OGLWidget" name="glwidget">
+      <property name="sizePolicy">
+       <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+        <horstretch>0</horstretch>
+        <verstretch>0</verstretch>
+       </sizepolicy>
+      </property>
+     </widget>
+    </item>
+   </layout>
+  </widget>
+  <widget class="QMenuBar" name="menuBar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>548</width>
+     <height>21</height>
+    </rect>
+   </property>
+  </widget>
+  <widget class="QToolBar" name="mainToolBar">
+   <attribute name="toolBarArea">
+    <enum>TopToolBarArea</enum>
+   </attribute>
+   <attribute name="toolBarBreak">
+    <bool>false</bool>
+   </attribute>
+  </widget>
+  <widget class="QStatusBar" name="statusBar"/>
+ </widget>
+ <layoutdefault spacing="6" margin="11"/>
+ <customwidgets>
+  <customwidget>
+   <class>OGLWidget</class>
+   <extends>QOpenGLWidget</extends>
+   <header>oglwidget.h</header>
+   <slots>
+    <slot>setParamA(double)</slot>
+    <slot>setParamB(double)</slot>
+   </slots>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>
diff --git a/hw04/mesh1.obj b/hw04/mesh1.obj
new file mode 100644
index 0000000..0af35e5
--- /dev/null
+++ b/hw04/mesh1.obj
@@ -0,0 +1,8 @@
+v  0  0  0
+v  8  0  0
+v  0  8  0
+v  0  0  8
+f  1 2 4
+f  2 3 4
+f  3 1 4
+f  3 2 1
\ No newline at end of file
diff --git a/hw04/oglwidget.cpp b/hw04/oglwidget.cpp
new file mode 100644
index 0000000..3be1f28
--- /dev/null
+++ b/hw04/oglwidget.cpp
@@ -0,0 +1,404 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "oglwidget.h"
+#include <math.h>
+#include <iostream>
+#include <iomanip>
+#include <fstream>
+#include <string>
+#include <vector>
+
+#define PI 3.14159265358979323846
+using namespace std;
+
+static double alpha = 45.0; // rotation angle
+
+class Vertex{
+public:
+    float p[3]; // coordinates
+
+    Vertex();
+    Vertex( float point[3]);
+    Vertex( float x, float y, float z);
+    void Print() {
+        cout << p[0] << " " << p[1] << " " << p[2] << endl;
+    }
+    // print coordinates on screen
+
+};
+
+Vertex::Vertex(){}; // empty constructor
+
+Vertex::Vertex(float x, float y, float z){ // constructor with initialization
+    p[0] = x;
+    p[1] = y;
+    p[2] = z;
+}
+
+Vertex::Vertex(float *point) {
+    copy_n(point, 3, p);
+}
+
+Vertex operator+( Vertex a, Vertex b) // add pts or vectors
+{
+    return *new Vertex(a.p[0] + b.p[0], a.p[1] + b.p[1],a.p[2] + b.p[2]);
+}
+Vertex operator-( Vertex a, Vertex b)// subtract pts or vectors
+{
+    return *new Vertex(a.p[0] - b.p[0], a.p[1] - b.p[1],a.p[2] - b.p[2]);
+}
+Vertex operator*( float a, Vertex b) // product between scalar and vector
+{
+    return *new Vertex(a*b.p[0], a*b.p[1], a*b.p[2]);
+}
+float operator*( Vertex a, Vertex b) // scalar product
+{
+    return a.p[0] * b.p[0] + a.p[1] * b.p[1] + a.p[2] * b.p[2];
+}
+Vertex operator%( Vertex a, Vertex b) // cross product
+{
+    return *new Vertex(a.p[1]*b.p[2] - a.p[2]*b.p[1], a.p[2]*b.p[0] - a.p[0]*b.p[2], a.p[0]*b.p[1] - a.p[1]*b.p[0]);
+}
+bool operator==(Vertex a, Vertex b) // check if coords are the same
+{
+    return (a.p[0] == b.p[0]) && (a.p[1] == b.p[1]) && (a.p[2] == b.p[2]);
+}
+
+class Tri
+{
+public:
+    int iv[3]; // vertex indices
+    int it[3]; // adjacent triangle indices
+    int ie[3]; // edge vertex indices
+    Tri();
+    Tri( int i[3]);
+    Tri( int i, int j, int k);
+    void Print();
+};
+
+void subDivEdgeMidpoint();
+
+void saveData();
+
+Tri::Tri() {
+    it[0] = -1;
+    it[1] = -1;
+    it[2] = -1;
+}
+
+Tri::Tri(int *i) {
+    new (this) Tri();
+
+}
+
+Tri::Tri(int i, int j, int k) {
+    new (this) Tri();
+
+    iv[0] = i;
+    iv[1] = j;
+    iv[2] = k;
+}
+
+
+vector <Vertex> pts;
+vector <int> valences;  // valence list (no. of triangles for every point
+vector <Tri> tris;
+
+void Tri::Print() {
+    cout << "Tri:" << endl << " neighbour: " << it[0] << " " << it[1] << " " << it[2] << endl << " - ";
+    cout << valences[iv[0]] << "x ";
+    pts[iv[0]].Print();
+    cout << " - " << valences[iv[1]] << "x ";
+    pts[iv[1]].Print();
+    cout << " - " << valences[iv[2]] << "x ";
+    pts[iv[2]].Print();
+    cout << endl;
+}
+
+
+void loadData()
+{
+    string fname = R"(C:\CLionProjects\cg\hw04\mesh1.obj)";
+    ifstream file( fname);
+    if (!file){
+        cout << "error opening file" << endl;
+        return;
+    }
+    string key;
+    while( file){
+        //getline( file, line);
+        file >> key;
+        if (key == "v") {
+            float x, y, z;
+            file >> x >> y >> z;
+            Vertex pVertex = *new Vertex(x, y, z);
+            pts.push_back(pVertex);
+            valences.push_back(0);
+        } else if (key == "f") {
+            int a, b, c;
+            file >> a >> b >> c;
+            Tri pTriangle = *new Tri(a-1, b-1, c-1);
+            tris.push_back(pTriangle);
+        }
+    }
+    file.close();
+
+    tris.pop_back();
+
+    subDivEdgeMidpoint();
+    subDivEdgeMidpoint();
+
+    // Connectivity Algorithm
+    for (int i = 0; i < tris.size(); ++i) {
+        Tri triag = tris[i];
+        int n = 0;
+        // Search for neighbour
+        for (int ti = 0; ti < tris.size(); ++ti) {
+            if (i == ti) continue;
+            Tri t = tris[ti];
+            int count = 0;
+            for (int x : triag.iv) {
+                for (int y : t.iv) {
+                    if (x == y)
+                        count++;
+                }
+            }
+            // if two points are the same, they are neighbours
+            if (count == 2)
+                triag.it[n++] = ti;
+        }
+
+        // increase valence for each vertex of triangle
+        valences[triag.iv[0]]++;
+        valences[triag.iv[1]]++;
+        valences[triag.iv[2]]++;
+
+        tris[i] = triag;
+    }
+
+    for (auto triag : tris) {
+        triag.Print();
+    }
+
+
+//    saveData();
+}
+
+void saveData() {
+    string fname = R"(C:\CLionProjects\cg\hw04\test2.obj)";
+    ofstream file( fname);
+    if (!file){
+        cout << "error opening file" << endl;
+        return;
+    }
+
+    for (auto vert : pts) {
+        file << "v\t" << vert.p[0] << "\t" << vert.p[1] << "\t" << vert.p[2] << endl;
+    }
+
+    for (auto triag : tris) {
+        file << "f\t" << triag.iv[0]+1 << "\t" << triag.iv[1]+1 << "\t" << triag.iv[2]+1 << endl;
+    }
+
+    file.close();
+}
+
+
+void subDivEdgeMidpoint() {
+    const unsigned long long int amountToSubDiv = tris.size();
+    for (int i = 0; i < amountToSubDiv; ++i) {
+        Tri triag = tris[i];
+
+        Vertex a = pts[triag.iv[0]];
+        Vertex b = pts[triag.iv[1]];
+        Vertex c = pts[triag.iv[2]];
+
+//        int e = pts.size();
+        int ei0 = -1;
+        int ei1 = -1;
+        int ei2 = -1;
+        Vertex e0 = 0.5f * (a+b);
+        Vertex e1 = 0.5f * (c+b);
+        Vertex e2 = 0.5f * (a+c);
+        for (int j = 0; j < pts.size(); ++j) {
+            if (pts[j] == e0)
+                ei0 = j;
+            if (pts[j] == e1)
+                ei1 = j;
+            if (pts[j] == e2)
+                ei2 = j;
+        }
+        if (ei0 == -1) {
+            ei0 = pts.size();
+            pts.push_back(e0);
+            valences.push_back(0);
+        }
+        if (ei1 == -1) {
+            ei1 = pts.size();
+            pts.push_back(e1);
+            valences.push_back(0);
+        }
+        if (ei2 == -1) {
+            ei2 = pts.size();
+            pts.push_back(e2);
+            valences.push_back(0);
+        }
+
+        tris.push_back(*new Tri(triag.iv[2], ei2, ei1));
+        tris.push_back(*new Tri(triag.iv[1], ei0, ei1));
+        tris.push_back(*new Tri(ei0, ei1, ei2));
+
+
+        triag.iv[1] = ei0;
+        triag.iv[2] = ei2;
+        tris[i] = triag;
+    }
+}
+
+void DrawTriag() {
+
+    glPolygonMode(GL_FRONT_AND_BACK , GL_LINE);
+    glBegin( GL_TRIANGLES);
+    for (auto tri : tris) {
+        Vertex a = pts[tri.iv[0]];
+        Vertex b = pts[tri.iv[1]];
+        Vertex c = pts[tri.iv[2]];
+        Vertex nvec = (b-a)%(c-a);
+
+        glNormal3fv(nvec.p);
+
+        glVertex3fv(a.p);
+        glVertex3fv(c.p);
+        glVertex3fv(b.p);
+
+    }
+    glEnd();
+}
+
+// initialize Open GL lighting and projection matrix
+void InitLightingAndProjection() // to be executed once before drawing
+{
+    // light positions and colors
+    GLfloat LightPosition1[4] = { 10, 5, 10,  0};
+    GLfloat LightPosition2[4] = { -5, 5, -10,  0};
+    GLfloat ColorRedish[4] = { 1.0,  .8,  .8,  1}; // white with a little bit of red
+    GLfloat ColorBlueish[4] = { .8,  .8,  1.0,  1};// white with a little bit of blue
+
+    glEnable( GL_DEPTH_TEST); // switch on z-buffer
+    glDepthFunc( GL_LESS);
+
+    glShadeModel( GL_SMOOTH); // Gouraud shading
+    //glShadeModel( GL_FLAT);
+
+    glEnable( GL_LIGHTING); // use lighting
+    glLightModeli( GL_LIGHT_MODEL_TWO_SIDE, 1); // draw both sides
+
+    // define and switch on light 0
+    glLightfv( GL_LIGHT0, GL_POSITION, LightPosition1);
+    glLightfv( GL_LIGHT0, GL_DIFFUSE,  ColorRedish);
+    glLightfv( GL_LIGHT0, GL_SPECULAR, ColorRedish);
+    glEnable( GL_LIGHT0);
+
+    // define and switch on light 1
+    glLightfv( GL_LIGHT1, GL_POSITION, LightPosition2);
+    glLightfv( GL_LIGHT1, GL_DIFFUSE,  ColorBlueish);
+    glLightfv( GL_LIGHT1, GL_SPECULAR, ColorBlueish);
+    glEnable( GL_LIGHT1);
+
+    glMatrixMode( GL_PROJECTION); // define camera projection
+    glLoadIdentity(); // reset matrix to identity (otherwise existing matrix will be multiplied with)
+    glOrtho( -15, 15, -10, 10, -50, 50); // orthogonal projection (xmin xmax ymin ymax zmin zmax)
+    //glFrustum( -10, 10, -8, 8, 2, 20); // perspective projektion
+}
+
+// define material color properties for front and back side
+void SetMaterialColor( int side, float r, float g, float b){
+    float	amb[4], dif[4], spe[4];
+    int	i, mat;
+
+    dif[0] = r; // diffuse color as defined by r,g, and b
+    dif[1] = g;
+    dif[2] = b;
+    for( i=0; i<3; i++){
+        amb[i] = .1 * dif[i]; // ambient color is 10 percent of diffuse
+        spe[i] = .5; // specular color is just white / gray
+    }
+    amb[3] = dif[3] = spe[3] = 1.0; // alpha component is always 1
+    switch( side){
+        case 1:	mat = GL_FRONT; break;
+        case 2:	mat = GL_BACK; break;
+        default: mat = GL_FRONT_AND_BACK; break;
+    }
+    glMaterialfv( mat, GL_AMBIENT, amb); // define ambient, diffuse and specular components
+    glMaterialfv( mat, GL_DIFFUSE, dif);
+    glMaterialfv( mat, GL_SPECULAR, spe);
+    glMaterialf( mat, GL_SHININESS, 50.0); // Phong constant for the size of highlights
+}
+
+
+OGLWidget::OGLWidget(QWidget *parent) // constructor
+    : QOpenGLWidget(parent)
+{
+    // Setup the animation timer to fire every x msec
+    animtimer = new QTimer(this);
+    animtimer->start( 50 );
+
+    // Everytime the timer fires, the animation is going one step forward
+    connect(animtimer, SIGNAL(timeout()), this, SLOT(stepAnimation()));
+
+    animstep = 0;
+}
+
+OGLWidget::~OGLWidget() // destructor
+{
+}
+
+void OGLWidget::stepAnimation()
+{
+    animstep++;    // Increase animation steps
+    update();      // Trigger redraw of scene with paintGL
+}
+
+void OGLWidget::initializeGL() // initializations to be called once
+{
+    initializeOpenGLFunctions();
+
+    InitLightingAndProjection(); // define light sources and projection
+
+    loadData();
+}
+
+void OGLWidget::paintGL() // draw everything, to be called repeatedly
+{
+    glEnable(GL_NORMALIZE); // this is necessary when using glScale (keep normals to unit length)
+
+    // set background color
+    glClearColor(0.8, 0.8, 1.0, 1.0); // bright blue
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+    // draw the scene
+    glMatrixMode( GL_MODELVIEW);
+    glLoadIdentity();				// Reset The Current Modelview Matrix
+    glTranslated( 0 ,0 ,-10.0);     // Move 10 units backwards in z, since camera is at origin
+    glScaled( 2.0, 2.0, 2.0);       // scale objects
+    glRotated( alpha, 0, 3, 1);     // continuous rotation
+    alpha += 2;
+
+    // define color: 1=front, 2=back, 3=both, followed by r, g, and b
+    SetMaterialColor( 1, 0, .2, .2);  // front color is red
+    SetMaterialColor( 2, 0.2, 0.2, 1.0); // back color is blue
+
+    // draw a cylinder with default resolution
+    DrawTriag();
+
+    // make it appear (before this, it's hidden in the rear buffer)
+    glFlush();
+}
+
+void OGLWidget::resizeGL(int w, int h) // called when window size is changed
+{
+    // adjust viewport transform
+    glViewport(0,0,w,h);
+}
+
diff --git a/hw04/oglwidget.h b/hw04/oglwidget.h
new file mode 100644
index 0000000..a536f6a
--- /dev/null
+++ b/hw04/oglwidget.h
@@ -0,0 +1,34 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#ifndef OGLWIDGET_H
+#define OGLWIDGET_H
+
+#include <QOpenGLWidget>
+#include <QOpenGLFunctions>
+#include <QTimer>
+
+class OGLWidget : public QOpenGLWidget,
+                  protected QOpenGLFunctions
+{
+    Q_OBJECT
+
+public:
+    OGLWidget(QWidget *parent = 0);
+    ~OGLWidget();
+
+public slots:
+    void stepAnimation();
+
+protected:
+    void initializeGL();
+    void resizeGL(int w, int h);
+    void paintGL();
+
+protected:
+    QTimer* animtimer; // Timer needed to step animation every x msec
+    int animstep;      // Current animation step (used to rotate triangle
+};
+
+
+#endif // OGLWIDGET_H
diff --git a/hw04/test.obj b/hw04/test.obj
new file mode 100644
index 0000000..678e09f
--- /dev/null
+++ b/hw04/test.obj
@@ -0,0 +1,98 @@
+v       0       0       0
+v       8       0       0
+v       0       8       0
+v       0       0       8
+v       4       0       0
+v       4       0       4
+v       0       0       4
+v       4       4       0
+v       0       4       4
+v       0       4       0
+v       2       0       0
+v       2       0       2
+v       0       0       2
+v       6       2       0
+v       4       2       2
+v       6       0       2
+v       0       6       0
+v       0       4       2
+v       0       6       2
+v       2       6       0
+v       2       4       0
+v       0       0       6
+v       2       0       4
+v       2       0       6
+v       6       0       0
+v       4       0       2
+v       2       2       4
+v       0       2       6
+v       2       4       2
+v       0       2       4
+v       0       2       0
+v       0       2       2
+v       2       2       0
+v       4       2       0
+f       1       11      13
+f       2       14      16
+f       3       17      19
+f       3       20      17
+f       4       22      24
+f       2       25      16
+f       5       26      12
+f       4       24      28
+f       3       20      19
+f       8       29      15
+f       4       28      22
+f       1       31      13
+f       10      32      18
+f       1       31      11
+f       2       14      25
+f       8       34      21
+f       7       13      12
+f       5       11      12
+f       11      12      13
+f       6       16      15
+f       8       14      15
+f       14      15      16
+f       9       19      18
+f       10      17      18
+f       17      18      19
+f       10      17      21
+f       8       20      21
+f       20      21      17
+f       6       24      23
+f       7       22      23
+f       22      23      24
+f       6       16      26
+f       5       25      26
+f       25      26      16
+f       7       12      23
+f       6       26      23
+f       26      23      12
+f       9       28      27
+f       6       24      27
+f       24      27      28
+f       9       19      29
+f       8       20      29
+f       20      29      19
+f       6       15      27
+f       9       29      27
+f       29      27      15
+f       7       22      30
+f       9       28      30
+f       28      30      22
+f       7       13      32
+f       10      31      32
+f       31      32      13
+f       9       18      30
+f       7       32      30
+f       32      30      18
+f       5       11      33
+f       10      31      33
+f       31      33      11
+f       5       25      34
+f       8       14      34
+f       14      34      25
+f       10      21      33
+f       5       34      33
+f       34      33      21
\ No newline at end of file

diff --git a/hw04/CMakeLists.txt b/hw04/CMakeLists.txt
new file mode 100644
index 0000000..4d596e0
--- /dev/null
+++ b/hw04/CMakeLists.txt
@@ -0,0 +1,58 @@
+cmake_minimum_required(VERSION 3.19)
+project(OpenGL_Example)
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_PREFIX_PATH "C:/Qt/Qt5.12.10/5.12.10/mingw73_64/lib/cmake")
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTORCC ON)
+set(CMAKE_AUTOUIC ON)
+
+set(QT_VERSION 5)
+set(REQUIRED_LIBS Core Gui Widgets)
+set(REQUIRED_LIBS_QUALIFIED Qt5::Core Qt5::Gui Qt5::Widgets)
+
+find_package(OpenGL REQUIRED)
+include_directories( ${OPENGL_INCLUDE_DIRS} )
+add_executable(OpenGL_Example
+        main.cpp
+        mainwindow.cpp
+        mainwindow.h
+        oglwidget.cpp
+        oglwidget.h)
+
+if (NOT CMAKE_PREFIX_PATH)
+    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
+            "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
+endif ()
+
+find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
+target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
+if (WIN32)
+    set(DEBUG_SUFFIX)
+    if (CMAKE_BUILD_TYPE MATCHES "Debug")
+        set(DEBUG_SUFFIX "d")
+    endif ()
+    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
+    if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        if (NOT EXISTS "${QT_INSTALL_PATH}/bin")
+            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
+        endif ()
+    endif ()
+    if (EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E make_directory
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
+    endif ()
+    foreach (QT_LIB ${REQUIRED_LIBS})
+        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
+                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
+    endforeach (QT_LIB)
+endif ()
diff --git a/hw04/OpenGL_Example.pro b/hw04/OpenGL_Example.pro
new file mode 100644
index 0000000..edf9575
--- /dev/null
+++ b/hw04/OpenGL_Example.pro
@@ -0,0 +1,27 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#-------------------------------------------------
+#
+# Project created by QtCreator 2016-03-04T23:07:51
+#
+#-------------------------------------------------
+
+QT       += core gui opengl
+
+LIBS    += -lOpengl32
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = opengl1
+TEMPLATE = app
+
+
+SOURCES += main.cpp\
+        mainwindow.cpp \
+    oglwidget.cpp
+
+HEADERS  += mainwindow.h \
+    oglwidget.h
+
+FORMS    += mainwindow.ui
diff --git a/hw04/main.cpp b/hw04/main.cpp
new file mode 100644
index 0000000..515e368
--- /dev/null
+++ b/hw04/main.cpp
@@ -0,0 +1,14 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    MainWindow w;
+    w.show();
+
+    return a.exec();
+}
diff --git a/hw04/mainwindow.cpp b/hw04/mainwindow.cpp
new file mode 100644
index 0000000..ff258c4
--- /dev/null
+++ b/hw04/mainwindow.cpp
@@ -0,0 +1,17 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+
+MainWindow::MainWindow(QWidget *parent) :
+    QMainWindow(parent),
+    ui(new Ui::MainWindow)
+{
+    ui->setupUi(this);
+}
+
+MainWindow::~MainWindow()
+{
+    delete ui;
+}
diff --git a/hw04/mainwindow.h b/hw04/mainwindow.h
new file mode 100644
index 0000000..b3aab25
--- /dev/null
+++ b/hw04/mainwindow.h
@@ -0,0 +1,25 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QMainWindow>
+
+namespace Ui {
+class MainWindow;
+}
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit MainWindow(QWidget *parent = 0);
+    ~MainWindow();
+
+private:
+    Ui::MainWindow *ui;
+};
+
+#endif // MAINWINDOW_H
diff --git a/hw04/mainwindow.ui b/hw04/mainwindow.ui
new file mode 100644
index 0000000..5e1745e
--- /dev/null
+++ b/hw04/mainwindow.ui
@@ -0,0 +1,64 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QMainWindow" name="MainWindow">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>548</width>
+    <height>415</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>MainWindow</string>
+  </property>
+  <widget class="QWidget" name="centralWidget">
+   <layout class="QVBoxLayout" name="verticalLayout">
+    <item>
+     <widget class="OGLWidget" name="glwidget">
+      <property name="sizePolicy">
+       <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+        <horstretch>0</horstretch>
+        <verstretch>0</verstretch>
+       </sizepolicy>
+      </property>
+     </widget>
+    </item>
+   </layout>
+  </widget>
+  <widget class="QMenuBar" name="menuBar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>548</width>
+     <height>21</height>
+    </rect>
+   </property>
+  </widget>
+  <widget class="QToolBar" name="mainToolBar">
+   <attribute name="toolBarArea">
+    <enum>TopToolBarArea</enum>
+   </attribute>
+   <attribute name="toolBarBreak">
+    <bool>false</bool>
+   </attribute>
+  </widget>
+  <widget class="QStatusBar" name="statusBar"/>
+ </widget>
+ <layoutdefault spacing="6" margin="11"/>
+ <customwidgets>
+  <customwidget>
+   <class>OGLWidget</class>
+   <extends>QOpenGLWidget</extends>
+   <header>oglwidget.h</header>
+   <slots>
+    <slot>setParamA(double)</slot>
+    <slot>setParamB(double)</slot>
+   </slots>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>
diff --git a/hw04/mesh1.obj b/hw04/mesh1.obj
new file mode 100644
index 0000000..0af35e5
--- /dev/null
+++ b/hw04/mesh1.obj
@@ -0,0 +1,8 @@
+v  0  0  0
+v  8  0  0
+v  0  8  0
+v  0  0  8
+f  1 2 4
+f  2 3 4
+f  3 1 4
+f  3 2 1
\ No newline at end of file
diff --git a/hw04/oglwidget.cpp b/hw04/oglwidget.cpp
new file mode 100644
index 0000000..3be1f28
--- /dev/null
+++ b/hw04/oglwidget.cpp
@@ -0,0 +1,404 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#include "oglwidget.h"
+#include <math.h>
+#include <iostream>
+#include <iomanip>
+#include <fstream>
+#include <string>
+#include <vector>
+
+#define PI 3.14159265358979323846
+using namespace std;
+
+static double alpha = 45.0; // rotation angle
+
+class Vertex{
+public:
+    float p[3]; // coordinates
+
+    Vertex();
+    Vertex( float point[3]);
+    Vertex( float x, float y, float z);
+    void Print() {
+        cout << p[0] << " " << p[1] << " " << p[2] << endl;
+    }
+    // print coordinates on screen
+
+};
+
+Vertex::Vertex(){}; // empty constructor
+
+Vertex::Vertex(float x, float y, float z){ // constructor with initialization
+    p[0] = x;
+    p[1] = y;
+    p[2] = z;
+}
+
+Vertex::Vertex(float *point) {
+    copy_n(point, 3, p);
+}
+
+Vertex operator+( Vertex a, Vertex b) // add pts or vectors
+{
+    return *new Vertex(a.p[0] + b.p[0], a.p[1] + b.p[1],a.p[2] + b.p[2]);
+}
+Vertex operator-( Vertex a, Vertex b)// subtract pts or vectors
+{
+    return *new Vertex(a.p[0] - b.p[0], a.p[1] - b.p[1],a.p[2] - b.p[2]);
+}
+Vertex operator*( float a, Vertex b) // product between scalar and vector
+{
+    return *new Vertex(a*b.p[0], a*b.p[1], a*b.p[2]);
+}
+float operator*( Vertex a, Vertex b) // scalar product
+{
+    return a.p[0] * b.p[0] + a.p[1] * b.p[1] + a.p[2] * b.p[2];
+}
+Vertex operator%( Vertex a, Vertex b) // cross product
+{
+    return *new Vertex(a.p[1]*b.p[2] - a.p[2]*b.p[1], a.p[2]*b.p[0] - a.p[0]*b.p[2], a.p[0]*b.p[1] - a.p[1]*b.p[0]);
+}
+bool operator==(Vertex a, Vertex b) // check if coords are the same
+{
+    return (a.p[0] == b.p[0]) && (a.p[1] == b.p[1]) && (a.p[2] == b.p[2]);
+}
+
+class Tri
+{
+public:
+    int iv[3]; // vertex indices
+    int it[3]; // adjacent triangle indices
+    int ie[3]; // edge vertex indices
+    Tri();
+    Tri( int i[3]);
+    Tri( int i, int j, int k);
+    void Print();
+};
+
+void subDivEdgeMidpoint();
+
+void saveData();
+
+Tri::Tri() {
+    it[0] = -1;
+    it[1] = -1;
+    it[2] = -1;
+}
+
+Tri::Tri(int *i) {
+    new (this) Tri();
+
+}
+
+Tri::Tri(int i, int j, int k) {
+    new (this) Tri();
+
+    iv[0] = i;
+    iv[1] = j;
+    iv[2] = k;
+}
+
+
+vector <Vertex> pts;
+vector <int> valences;  // valence list (no. of triangles for every point
+vector <Tri> tris;
+
+void Tri::Print() {
+    cout << "Tri:" << endl << " neighbour: " << it[0] << " " << it[1] << " " << it[2] << endl << " - ";
+    cout << valences[iv[0]] << "x ";
+    pts[iv[0]].Print();
+    cout << " - " << valences[iv[1]] << "x ";
+    pts[iv[1]].Print();
+    cout << " - " << valences[iv[2]] << "x ";
+    pts[iv[2]].Print();
+    cout << endl;
+}
+
+
+void loadData()
+{
+    string fname = R"(C:\CLionProjects\cg\hw04\mesh1.obj)";
+    ifstream file( fname);
+    if (!file){
+        cout << "error opening file" << endl;
+        return;
+    }
+    string key;
+    while( file){
+        //getline( file, line);
+        file >> key;
+        if (key == "v") {
+            float x, y, z;
+            file >> x >> y >> z;
+            Vertex pVertex = *new Vertex(x, y, z);
+            pts.push_back(pVertex);
+            valences.push_back(0);
+        } else if (key == "f") {
+            int a, b, c;
+            file >> a >> b >> c;
+            Tri pTriangle = *new Tri(a-1, b-1, c-1);
+            tris.push_back(pTriangle);
+        }
+    }
+    file.close();
+
+    tris.pop_back();
+
+    subDivEdgeMidpoint();
+    subDivEdgeMidpoint();
+
+    // Connectivity Algorithm
+    for (int i = 0; i < tris.size(); ++i) {
+        Tri triag = tris[i];
+        int n = 0;
+        // Search for neighbour
+        for (int ti = 0; ti < tris.size(); ++ti) {
+            if (i == ti) continue;
+            Tri t = tris[ti];
+            int count = 0;
+            for (int x : triag.iv) {
+                for (int y : t.iv) {
+                    if (x == y)
+                        count++;
+                }
+            }
+            // if two points are the same, they are neighbours
+            if (count == 2)
+                triag.it[n++] = ti;
+        }
+
+        // increase valence for each vertex of triangle
+        valences[triag.iv[0]]++;
+        valences[triag.iv[1]]++;
+        valences[triag.iv[2]]++;
+
+        tris[i] = triag;
+    }
+
+    for (auto triag : tris) {
+        triag.Print();
+    }
+
+
+//    saveData();
+}
+
+void saveData() {
+    string fname = R"(C:\CLionProjects\cg\hw04\test2.obj)";
+    ofstream file( fname);
+    if (!file){
+        cout << "error opening file" << endl;
+        return;
+    }
+
+    for (auto vert : pts) {
+        file << "v\t" << vert.p[0] << "\t" << vert.p[1] << "\t" << vert.p[2] << endl;
+    }
+
+    for (auto triag : tris) {
+        file << "f\t" << triag.iv[0]+1 << "\t" << triag.iv[1]+1 << "\t" << triag.iv[2]+1 << endl;
+    }
+
+    file.close();
+}
+
+
+void subDivEdgeMidpoint() {
+    const unsigned long long int amountToSubDiv = tris.size();
+    for (int i = 0; i < amountToSubDiv; ++i) {
+        Tri triag = tris[i];
+
+        Vertex a = pts[triag.iv[0]];
+        Vertex b = pts[triag.iv[1]];
+        Vertex c = pts[triag.iv[2]];
+
+//        int e = pts.size();
+        int ei0 = -1;
+        int ei1 = -1;
+        int ei2 = -1;
+        Vertex e0 = 0.5f * (a+b);
+        Vertex e1 = 0.5f * (c+b);
+        Vertex e2 = 0.5f * (a+c);
+        for (int j = 0; j < pts.size(); ++j) {
+            if (pts[j] == e0)
+                ei0 = j;
+            if (pts[j] == e1)
+                ei1 = j;
+            if (pts[j] == e2)
+                ei2 = j;
+        }
+        if (ei0 == -1) {
+            ei0 = pts.size();
+            pts.push_back(e0);
+            valences.push_back(0);
+        }
+        if (ei1 == -1) {
+            ei1 = pts.size();
+            pts.push_back(e1);
+            valences.push_back(0);
+        }
+        if (ei2 == -1) {
+            ei2 = pts.size();
+            pts.push_back(e2);
+            valences.push_back(0);
+        }
+
+        tris.push_back(*new Tri(triag.iv[2], ei2, ei1));
+        tris.push_back(*new Tri(triag.iv[1], ei0, ei1));
+        tris.push_back(*new Tri(ei0, ei1, ei2));
+
+
+        triag.iv[1] = ei0;
+        triag.iv[2] = ei2;
+        tris[i] = triag;
+    }
+}
+
+void DrawTriag() {
+
+    glPolygonMode(GL_FRONT_AND_BACK , GL_LINE);
+    glBegin( GL_TRIANGLES);
+    for (auto tri : tris) {
+        Vertex a = pts[tri.iv[0]];
+        Vertex b = pts[tri.iv[1]];
+        Vertex c = pts[tri.iv[2]];
+        Vertex nvec = (b-a)%(c-a);
+
+        glNormal3fv(nvec.p);
+
+        glVertex3fv(a.p);
+        glVertex3fv(c.p);
+        glVertex3fv(b.p);
+
+    }
+    glEnd();
+}
+
+// initialize Open GL lighting and projection matrix
+void InitLightingAndProjection() // to be executed once before drawing
+{
+    // light positions and colors
+    GLfloat LightPosition1[4] = { 10, 5, 10,  0};
+    GLfloat LightPosition2[4] = { -5, 5, -10,  0};
+    GLfloat ColorRedish[4] = { 1.0,  .8,  .8,  1}; // white with a little bit of red
+    GLfloat ColorBlueish[4] = { .8,  .8,  1.0,  1};// white with a little bit of blue
+
+    glEnable( GL_DEPTH_TEST); // switch on z-buffer
+    glDepthFunc( GL_LESS);
+
+    glShadeModel( GL_SMOOTH); // Gouraud shading
+    //glShadeModel( GL_FLAT);
+
+    glEnable( GL_LIGHTING); // use lighting
+    glLightModeli( GL_LIGHT_MODEL_TWO_SIDE, 1); // draw both sides
+
+    // define and switch on light 0
+    glLightfv( GL_LIGHT0, GL_POSITION, LightPosition1);
+    glLightfv( GL_LIGHT0, GL_DIFFUSE,  ColorRedish);
+    glLightfv( GL_LIGHT0, GL_SPECULAR, ColorRedish);
+    glEnable( GL_LIGHT0);
+
+    // define and switch on light 1
+    glLightfv( GL_LIGHT1, GL_POSITION, LightPosition2);
+    glLightfv( GL_LIGHT1, GL_DIFFUSE,  ColorBlueish);
+    glLightfv( GL_LIGHT1, GL_SPECULAR, ColorBlueish);
+    glEnable( GL_LIGHT1);
+
+    glMatrixMode( GL_PROJECTION); // define camera projection
+    glLoadIdentity(); // reset matrix to identity (otherwise existing matrix will be multiplied with)
+    glOrtho( -15, 15, -10, 10, -50, 50); // orthogonal projection (xmin xmax ymin ymax zmin zmax)
+    //glFrustum( -10, 10, -8, 8, 2, 20); // perspective projektion
+}
+
+// define material color properties for front and back side
+void SetMaterialColor( int side, float r, float g, float b){
+    float	amb[4], dif[4], spe[4];
+    int	i, mat;
+
+    dif[0] = r; // diffuse color as defined by r,g, and b
+    dif[1] = g;
+    dif[2] = b;
+    for( i=0; i<3; i++){
+        amb[i] = .1 * dif[i]; // ambient color is 10 percent of diffuse
+        spe[i] = .5; // specular color is just white / gray
+    }
+    amb[3] = dif[3] = spe[3] = 1.0; // alpha component is always 1
+    switch( side){
+        case 1:	mat = GL_FRONT; break;
+        case 2:	mat = GL_BACK; break;
+        default: mat = GL_FRONT_AND_BACK; break;
+    }
+    glMaterialfv( mat, GL_AMBIENT, amb); // define ambient, diffuse and specular components
+    glMaterialfv( mat, GL_DIFFUSE, dif);
+    glMaterialfv( mat, GL_SPECULAR, spe);
+    glMaterialf( mat, GL_SHININESS, 50.0); // Phong constant for the size of highlights
+}
+
+
+OGLWidget::OGLWidget(QWidget *parent) // constructor
+    : QOpenGLWidget(parent)
+{
+    // Setup the animation timer to fire every x msec
+    animtimer = new QTimer(this);
+    animtimer->start( 50 );
+
+    // Everytime the timer fires, the animation is going one step forward
+    connect(animtimer, SIGNAL(timeout()), this, SLOT(stepAnimation()));
+
+    animstep = 0;
+}
+
+OGLWidget::~OGLWidget() // destructor
+{
+}
+
+void OGLWidget::stepAnimation()
+{
+    animstep++;    // Increase animation steps
+    update();      // Trigger redraw of scene with paintGL
+}
+
+void OGLWidget::initializeGL() // initializations to be called once
+{
+    initializeOpenGLFunctions();
+
+    InitLightingAndProjection(); // define light sources and projection
+
+    loadData();
+}
+
+void OGLWidget::paintGL() // draw everything, to be called repeatedly
+{
+    glEnable(GL_NORMALIZE); // this is necessary when using glScale (keep normals to unit length)
+
+    // set background color
+    glClearColor(0.8, 0.8, 1.0, 1.0); // bright blue
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+    // draw the scene
+    glMatrixMode( GL_MODELVIEW);
+    glLoadIdentity();				// Reset The Current Modelview Matrix
+    glTranslated( 0 ,0 ,-10.0);     // Move 10 units backwards in z, since camera is at origin
+    glScaled( 2.0, 2.0, 2.0);       // scale objects
+    glRotated( alpha, 0, 3, 1);     // continuous rotation
+    alpha += 2;
+
+    // define color: 1=front, 2=back, 3=both, followed by r, g, and b
+    SetMaterialColor( 1, 0, .2, .2);  // front color is red
+    SetMaterialColor( 2, 0.2, 0.2, 1.0); // back color is blue
+
+    // draw a cylinder with default resolution
+    DrawTriag();
+
+    // make it appear (before this, it's hidden in the rear buffer)
+    glFlush();
+}
+
+void OGLWidget::resizeGL(int w, int h) // called when window size is changed
+{
+    // adjust viewport transform
+    glViewport(0,0,w,h);
+}
+
diff --git a/hw04/oglwidget.h b/hw04/oglwidget.h
new file mode 100644
index 0000000..a536f6a
--- /dev/null
+++ b/hw04/oglwidget.h
@@ -0,0 +1,34 @@
+// Copyright (c) 2021. Pascal Syma <pascal@syma.dev> and Antonio Martinez Casadesus <acasadesus@stud.hs-bremen.de>.
+// All rights reserved.
+
+#ifndef OGLWIDGET_H
+#define OGLWIDGET_H
+
+#include <QOpenGLWidget>
+#include <QOpenGLFunctions>
+#include <QTimer>
+
+class OGLWidget : public QOpenGLWidget,
+                  protected QOpenGLFunctions
+{
+    Q_OBJECT
+
+public:
+    OGLWidget(QWidget *parent = 0);
+    ~OGLWidget();
+
+public slots:
+    void stepAnimation();
+
+protected:
+    void initializeGL();
+    void resizeGL(int w, int h);
+    void paintGL();
+
+protected:
+    QTimer* animtimer; // Timer needed to step animation every x msec
+    int animstep;      // Current animation step (used to rotate triangle
+};
+
+
+#endif // OGLWIDGET_H
diff --git a/hw04/test.obj b/hw04/test.obj
new file mode 100644
index 0000000..678e09f
--- /dev/null
+++ b/hw04/test.obj
@@ -0,0 +1,98 @@
+v       0       0       0
+v       8       0       0
+v       0       8       0
+v       0       0       8
+v       4       0       0
+v       4       0       4
+v       0       0       4
+v       4       4       0
+v       0       4       4
+v       0       4       0
+v       2       0       0
+v       2       0       2
+v       0       0       2
+v       6       2       0
+v       4       2       2
+v       6       0       2
+v       0       6       0
+v       0       4       2
+v       0       6       2
+v       2       6       0
+v       2       4       0
+v       0       0       6
+v       2       0       4
+v       2       0       6
+v       6       0       0
+v       4       0       2
+v       2       2       4
+v       0       2       6
+v       2       4       2
+v       0       2       4
+v       0       2       0
+v       0       2       2
+v       2       2       0
+v       4       2       0
+f       1       11      13
+f       2       14      16
+f       3       17      19
+f       3       20      17
+f       4       22      24
+f       2       25      16
+f       5       26      12
+f       4       24      28
+f       3       20      19
+f       8       29      15
+f       4       28      22
+f       1       31      13
+f       10      32      18
+f       1       31      11
+f       2       14      25
+f       8       34      21
+f       7       13      12
+f       5       11      12
+f       11      12      13
+f       6       16      15
+f       8       14      15
+f       14      15      16
+f       9       19      18
+f       10      17      18
+f       17      18      19
+f       10      17      21
+f       8       20      21
+f       20      21      17
+f       6       24      23
+f       7       22      23
+f       22      23      24
+f       6       16      26
+f       5       25      26
+f       25      26      16
+f       7       12      23
+f       6       26      23
+f       26      23      12
+f       9       28      27
+f       6       24      27
+f       24      27      28
+f       9       19      29
+f       8       20      29
+f       20      29      19
+f       6       15      27
+f       9       29      27
+f       29      27      15
+f       7       22      30
+f       9       28      30
+f       28      30      22
+f       7       13      32
+f       10      31      32
+f       31      32      13
+f       9       18      30
+f       7       32      30
+f       32      30      18
+f       5       11      33
+f       10      31      33
+f       31      33      11
+f       5       25      34
+f       8       14      34
+f       14      34      25
+f       10      21      33
+f       5       34      33
+f       34      33      21
\ No newline at end of file
diff --git a/hw04/test2.obj b/hw04/test2.obj
new file mode 100644
index 0000000..23acc46
--- /dev/null
+++ b/hw04/test2.obj
@@ -0,0 +1,26 @@
+v	0	0	0
+v	8	0	0
+v	0	8	0
+v	0	0	8
+v	4	0	0
+v	4	0	4
+v	0	0	4
+v	4	4	0
+v	0	4	4
+v	0	4	0
+f	1	5	7
+f	2	8	6
+f	3	10	9
+f	3	8	10
+f	4	7	6
+f	2	5	6
+f	5	6	7
+f	4	6	9
+f	3	8	9
+f	8	9	6
+f	4	9	7
+f	1	10	7
+f	10	7	9
+f	1	10	5
+f	2	8	5
+f	8	5	10