[comp.sys.mac.programmer] Dissolve effect

bolter@unc.cs.unc.edu (Jay D. Bolter) (09/23/90)

  I would like to be able duplicate in my own programs the visual dissolve 
effect in Hypercard. That is, I would like to make the pixels of a window 
change quickly and randomly from one image to a new image. This trick was 
discussed a few months ago on the net. I believe the suggestion was to draw 
the new image offscreen and then call copybits repeatedly with a suitable 
mask that changes with each call. Can anyone provide me with the details (in 
particular how do you create and update the mask?), or with a pointer to an 
article on this subject?