>Psychtoolbox>PsychDemos

GarboriumDemo([ngabors=200] [, internalRotation=0]) – An aquarium full of cute little gabors!

This demo shows how to use the Screen(‘DrawTextures’) command to draw a
large number of similar images quickly - in this case, Gabor patches of
different position, size and orientation. It also shows how to achieve
fast, mathematically correct, linear superposition of image patches by
use of alpha blending and the Psychtoolbox imaging pipeline. While you
could always achieve proper superposition by precomputing large images in
Matlab, then drawing them as textures, the use of alpha blending allows
to offload the computations to your graphics hardware - this allows
speedups by factors of more than 100x in some cases!

The demo shows “an aquarium” of many cute little gabor patches, each moving
into a random direction. Sometimes the gabors intersect, in that case
you’ll see a linear superposition of them.

Each frame of the animation contains ‘ngabors’ patches, ngabors defaults
to 200. Change the number as first optional parameter ‘ngabors’ if you want
to exercise your graphics hardware and cpu.

Normally the gabor paches rotate as a whole, a different method of
rotation is so called internal texture rotation (see comments in code),
which can be selected by setting the optional 2nd argument
‘internalRotation’ to a value of 1.

You can exit the demo by pressing any key on the keyboard.

This demo needs recent graphics hardware with floating point framebuffer
support: ATI Radeon X1000 and later, NVidia GeForce 6000 and later.