main.cpp Example File

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  #include "openglwindow.h"

  #include <QtGui/QGuiApplication>
  #include <QtGui/QMatrix4x4>
  #include <QtGui/QOpenGLShaderProgram>
  #include <QtGui/QScreen>

  #include <QtCore/qmath.h>

  class TriangleWindow : public OpenGLWindow
  {
  public:
      TriangleWindow();

      void initialize() override;
      void render() override;

  private:
      GLuint m_posAttr;
      GLuint m_colAttr;
      GLuint m_matrixUniform;

      QOpenGLShaderProgram *m_program;
      int m_frame;
  };

  TriangleWindow::TriangleWindow()
      : m_program(0)
      , m_frame(0)
  {
  }

  int main(int argc, char **argv)
  {
      QGuiApplication app(argc, argv);

      QSurfaceFormat format;
      format.setSamples(16);

      TriangleWindow window;
      window.setFormat(format);
      window.resize(640, 480);
      window.show();

      window.setAnimating(true);

      return app.exec();
  }

  static const char *vertexShaderSource =
      "attribute highp vec4 posAttr;\n"
      "attribute lowp vec4 colAttr;\n"
      "varying lowp vec4 col;\n"
      "uniform highp mat4 matrix;\n"
      "void main() {\n"
      "   col = colAttr;\n"
      "   gl_Position = matrix * posAttr;\n"
      "}\n";

  static const char *fragmentShaderSource =
      "varying lowp vec4 col;\n"
      "void main() {\n"
      "   gl_FragColor = col;\n"
      "}\n";

  void TriangleWindow::initialize()
  {
      m_program = new QOpenGLShaderProgram(this);
      m_program->addShaderFromSourceCode(QOpenGLShader::Vertex, vertexShaderSource);
      m_program->addShaderFromSourceCode(QOpenGLShader::Fragment, fragmentShaderSource);
      m_program->link();
      m_posAttr = m_program->attributeLocation("posAttr");
      m_colAttr = m_program->attributeLocation("colAttr");
      m_matrixUniform = m_program->uniformLocation("matrix");
  }

  void TriangleWindow::render()
  {
      const qreal retinaScale = devicePixelRatio();
      glViewport(0, 0, width() * retinaScale, height() * retinaScale);

      glClear(GL_COLOR_BUFFER_BIT);

      m_program->bind();

      QMatrix4x4 matrix;
      matrix.perspective(60.0f, 4.0f/3.0f, 0.1f, 100.0f);
      matrix.translate(0, 0, -2);
      matrix.rotate(100.0f * m_frame / screen()->refreshRate(), 0, 1, 0);

      m_program->setUniformValue(m_matrixUniform, matrix);

      GLfloat vertices[] = {
          0.0f, 0.707f,
          -0.5f, -0.5f,
          0.5f, -0.5f
      };

      GLfloat colors[] = {
          1.0f, 0.0f, 0.0f,
          0.0f, 1.0f, 0.0f,
          0.0f, 0.0f, 1.0f
      };

      glVertexAttribPointer(m_posAttr, 2, GL_FLOAT, GL_FALSE, 0, vertices);
      glVertexAttribPointer(m_colAttr, 3, GL_FLOAT, GL_FALSE, 0, colors);

      glEnableVertexAttribArray(0);
      glEnableVertexAttribArray(1);

      glDrawArrays(GL_TRIANGLES, 0, 3);

      glDisableVertexAttribArray(1);
      glDisableVertexAttribArray(0);

      m_program->release();

      ++m_frame;
  }