MATLAB Programming/Psychtoolbox/Screen Commands/DrawOval

Usage:

Screen(windowPtr,'FillOval',[color],[rect])

Fills an ellipse with the given color, inscribed within rect.color is the clut index (scalar or [r g b] triplet) that you want to poke into each pixel; default produces white with the standard CLUT for this window's pixelSize. Default rect is whole window.