[gratingid, gratingrect] = CreateProceduralSquareWaveGrating(windowPtr, width, height [, backgroundColorOffset =(0,0,0,0)] [, radius=inf][, contrastPreMultiplicator=1])

Creates a procedural texture that allows to draw square wave grating stimulus patches
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’ Optional parameter. If specified, a circular aperture of
‘radius’ pixels is applied to the grating. By default, no aperture is

‘contrastPreMultiplicator’ Optional, defaults to 1. This value is
multiplied as a scaling factor to the requested contrast value. If you
specify contrastPreMultiplicator = 0.5 then the per grating ‘contrast’
value will correspond to what practitioners of the field usually
understand to be the contrast value of a grating.

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

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