>Psychtoolbox>PsychGLImageProcessing

[discid, discrect] = CreateProceduralSmoothedDisc(windowPtr, width, height
[, backgroundColorOffset =(0,0,0,0)] [, radius=inf] [, sigma=11] [,useAlpha=1] [,method=1])

Creates a procedural texture that allows to draw smoothed discs
in a very fast and efficient manner on modern graphics hardware.

‘windowPtr’ A handle to the onscreen window.

‘width’ x ‘height’ The maximum size (in pixels) of the grating. More
precise, the size of the mathematical support of the grating. Providing too
small values here would ‘cut off’ peripheral parts or your grating. Too big
values don’t hurt wrt. correctness or accuracy, they just hurt
performance, ie. drawing speed. Use a reasonable size for your purpose.

‘backgroundColorOffset’ Optional, defaults to [0 0 0 0]. A RGBA offset
color to add to the final RGBA colors of the drawn grating, prior to
drawing it.

‘radius’ If specified, a circular aperture of
‘radius’ pixels is applied to the grating. By default, aperture == width.

‘sigma’ edge smoothing value in pixels

‘useAlpha’ whether to use colour (0) or alpha (1) for smoothing channel

‘method’ whether to use cosine (0) or smoothstep (1) functions. If you
pass (2) then the smoothstep will be inverted, so you can use it as a
mask (see ProceduralSmoothedDiscMaskDemo.m for example).

The function returns a procedural texture handle that you can
pass to the Screen(‘DrawTexture(s)’, windowPtr, id, …) functions
like any other texture handle. The ‘discrect’ is a rectangle which
describes the size of the support.