How to use OpenGL functions in QT OpenGL Widget?

Question

I start with the QT 4.6 "OpenGL - 2D painting" example
It uses a subclass of QGLWidget and performs drawing operations with the QPainter class.
I would like to know how to draw directly with OpenGL functions on an OpenGL widget.

Answer 1

If you use the widget as described in its guide , you can simply use the OpenGL functions as usual. For example (copied from the manual):

class MyGLDrawer : public QGLWidget { Q_OBJECT // must include this if you use Qt signals/slots public: MyGLDrawer(QWidget *parent) : QGLWidget(parent) {} protected: void initializeGL() { // Set up the rendering context, define display lists etc.: ... glClearColor(0.0, 0.0, 0.0, 0.0); glEnable(GL_DEPTH_TEST); ... } void resizeGL(int w, int h) { // setup viewport, projection etc.: glViewport(0, 0, (GLint)w, (GLint)h); ... glFrustum(...); ... } void paintGL() { // draw the scene: ... glRotatef(...); glMaterialfv(...); glBegin(GL_QUADS); glVertex3f(...); glVertex3f(...); ... glEnd(); ... } };