Mastering GUI Programming with Python

Animating in OpenGL

Animating our wedge is purely a matter of manipulating the view matrix and redrawing our image. We'll start in GlWidget.initializeGL() by creating an instance variable to hold rotation values:

        self.rotation = [0, 0, 0, 0]

The first value in this list represents an angle of rotation; the remaining values are the X, Y, and Z coordinates of the point around which the view matrix will rotate.

At the end of paintGL(), we can pass these values into the matrix object's rotate() method:

        self.view_matrix.rotate(*self.rotation)

Right now, this will do nothing, because our rotation values are all 0. To cause rotation, we will have to change self.rotation and trigger a repaint of the image.

So, our rotation callbacks will look like ...