MATLAB Programming/Psychtoolbox/Screen Commands/FrameArc
Draw an arc inscribed within the rect. color is the clut index (scalar or [r g b] triplet) that you want to poke into each pixel; default produces black with the standard CLUT for this window's pixelSize. Default rect is entire window. Default pen size is 1,1. Angles are measured in degrees, clockwise from vertical.