rotation drawing

1
dear psychtoolbox users,

i have been using this toolbox to draw my visual stimuli and now I
have some questions. I am drawing a rotation stimuli. The strategy I
am now using is
a) pre-draw each frames in a matrix and save it.
b) load it to the offscreen window when doing the experiment.
c) Then present them continuously.
As I have a large group of frames, step a) and b) would cost a lot
of time. The only difference between frames was the phase (rotate a
little). So is it possible to have only one frame of the picture and
only change the phase when loading to different offscreen window? Or,
better, only change the phase while put the offscreen window to the
'onscreen' one? If both was impossible, is there any other way to
reduce the time?

btw: matlab6.5@windows

Sorry to post again, because the origin mail was neglected...
2
If you would use Psychtoolbox 1.0.6 for MacOS-X, you could use the
Screen('MakeTexture',...) command, which allows rotated drawing
of images - use one image, draw it with some different angle in
each successive frame.

On Windows, this is not supported: If you have the Matlab image
processing toolbox installed, have
a look at "help imrotate" on how to rotate your image before
putting it into an offscreen window.

Otherwise, you're on your own and your current solution is the
best i know of.

-mario


--- In psychtoolbox@yahoogroups.com, peng <prion.w@g...> wrote:
> dear psychtoolbox users,
>
> i have been using this toolbox to draw my visual stimuli and now I
> have some questions. I am drawing a rotation stimuli. The strategy I
> am now using is
> a) pre-draw each frames in a matrix and save it.
> b) load it to the offscreen window when doing the experiment.
> c) Then present them continuously.
> As I have a large group of frames, step a) and b) would cost a lot
> of time. The only difference between frames was the phase (rotate a
> little). So is it possible to have only one frame of the picture and
> only change the phase when loading to different offscreen window?
Or,
> better, only change the phase while put the offscreen window to the
> 'onscreen' one? If both was impossible, is there any other way to
> reduce the time?
>
> btw: matlab6.5@windows
>
> Sorry to post again, because the origin mail was neglected...