Psychtoolbox>Screen.{mex*} subfunction

Screen(‘FramePoly’, windowPtr [,color], pointList [,penWidth]);

Draw a polygon frame. “color” is the clut index (scalar or [r g b a] vector)
that you want to poke into each pixel; default produces white. “pointList” is a
matrix: each row specifies the (x,y) coordinates of a vertex.

###See also: FillPoly