>Psychtoolbox>PsychDemos

dot motion demo using SCREEN(‘DrawDots’) subfunction

Usage: DotDemo([showSprites = 0][, waitframes = 1]);

The optional parameter ‘showSprites’ when set to 1, will draw little
smiley textures instead of dots, demonstrating sprite-drawing. A zero
setting, or omitting the setting, will draw dots. A value of 2 will draw
filled rectangles via textures instead, (ab-)using texture drawing and
filtering to allow subpixel positioning of drawn rectangles on the
screen. We slow down the animation for non-zero ‘showSprites’ so you can
appreciate the anti-aliased smooth subpixel movement better.

‘waitframes’ Number of video refresh intervals to show each image before
updating the dot field. Defaults to 1 if omitted.

You can exit the demo by any keypress or mouse button press. It will also
exit by itself after 1000 redraws.

The top of the demo code contains tons of parameters to tweak and
manipulate if you want.

Note: Some versions of MacOS/X have defective dot drawing due to an
operating system bug. If you happen to have such a system (e.g., OS/X
10.6.3 with NVidia Geforce-7xxx hardware) then read “help ScreenDrawDots”
for a workaround.