Colored Squares

Overview

Colored Squares is a cross-platform Qt 6 demonstration app that illustrates how to integrate modern OpenGL (4.6 Core Profile) into a Qt Widgets application.
The program opens a main window, requests an OpenGL 4.6 core context, and uses a custom QOpenGLWidget subclass (View) to render a simple 2D scene — a ground strip and a pyramid of brightly coloured squares stacked in layers.

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Features

• Uses OpenGL 4.6 Core Profile (no deprecated fixed-pipeline functions)
• Draws a pyramid of colored squares using modern buffer/shader APIs
• Includes an orthographic projection that adapts to window resizing
• Automatically sets up Qt application icons for window, taskbar, and executable
• Built with CMake, GLM, and Qt 6

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Prerequisites

Before building, ensure the following dependencies are installed:

Dependency	Minimum Version	Purpose
Qt 6	6.5 or newer	Core / Gui / Widgets / OpenGL / OpenGLWidgets
CMake	3.21 or newer	Build system
GLM	Latest	Math library for transformations
MinGW	Qt-provided toolchain	Compiler

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How It Works

Rendering

• A unit square is defined as two triangles stored in a Vertex Buffer Object (VBO).
• A Vertex Array Object (VAO) is used to describe how vertex data is interpreted.
• A minimal GLSL shader program transforms each vertex using a Model–View–Projection (MVP) matrix and colors it with a uniform RGBA value.
• Multiple squares are drawn at different positions and with different colors to form a pyramid:
  • Base row: four colored squares (red, green, blue, orange)
  • Second row: three squares (violet, yellow, turquoise)
  • Top row: one pink square
• A gray “ground strip” is drawn beneath the pyramid for depth reference.

OpenGL Setup

• The application requests a Core Profile OpenGL 4.6 context using QSurfaceFormat.
• The context is initialized in View::initializeGL() where shaders and buffers are created.
• Each frame is rendered inside paintGL(), which:
  1. Clears the framebuffer with a dark gray-blue color.
  2. Binds the shader program and VAO.
  3. Uploads new transformation matrices and color uniforms.
  4. Issues draw calls with glDrawArrays(GL_TRIANGLES) for each square.
• The projection is orthographic and recalculated on every window resize in resizeGL() to maintain proper aspect ratio.

Shader Pipeline

• Vertex Shader (#version 450 core):

  layout(location = 0) in vec3 position;
  uniform mat4 mvp;
  void main()
  {
      gl_Position = mvp * vec4(position, 1.0);
  }

• Fragment Shader (#version 450 core):

  uniform vec4 color;
  out vec4 FragColor;
  void main()
  {
      FragColor = color;
  }

• These shaders are compiled, linked, and cached during initialization.

Icon System

• The app includes two icons inside Icon/:
  • Icon/Icon.png — used for window and taskbar icons.
  • Icon/icon.ico — embedded in the executable for Windows Explorer.
• Qt Resource System (resources.qrc) embeds both files into the binary.
• Windows Resource Script (appicon.rc) ensures the .exe displays the correct icon in file explorer.
• Both resources are added in CMakeLists.txt under the add_executable() target.

CMake & Build Integration

• CMake enables Qt’s automatic tools:

  set(CMAKE_AUTOMOC ON)
  set(CMAKE_AUTORCC ON)
  set(CMAKE_AUTOUIC ON)

• GLM is fetched automatically via:

  FetchContent_Declare(
      glm
      GIT_REPOSITORY https://github.com/g-truc/glm.git
      GIT_TAG master)
  FetchContent_MakeAvailable(glm)

• In add_executable, there is "WIN32" that will disable the default console in both IDE and .exe. If removed, it will re-enable it.

Deployment Notes

To ensure full runtime compatibility, you can also use:

windeployqt --compiler-runtime --no-translations build/Colored_squares.exe

This command bundles all required Qt and MinGW runtime libraries for distribution.

Customization Tips

• Change colors inside View::paintGL() where each square’s RGBA values are set.
• Adjust the number and spacing of squares for different arrangements.
• Replace the icons in Icon/ to rebrand the application.
• Modify CMakeLists.txt if you add new source files or Qt modules.

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License

This project is provided for educational and demonstration purposes.
You are free to reuse, modify, or extend it in your own Qt or OpenGL-based projects.