OpenGL Overlay Example

This example demonstrates how to use OpenGL overlays with the Qt OpenGL Extension. It features a QGLWidget with a relatively expensive redrawing operation, and rubber-band drawing in the overlay plane. Using the overlay has the advantage that the rubber-band may be drawn and erased without damaging the image in the main plane, so costly redraws are avoided.

See $QTDIR/examples/opengl/overlay for the source code.