krowney@sonia.math.ucla.edu (10/05/89)
I have been experimenting with low level graphics on the Mac for a week now. Early on I discovered the need to use the Vertical Retrace Queue to do smooth animation. Most of the flickering and jittering associated with animation has been cured, but I am still left with an anomaly I can't seem to get around. The anomaly seems to appear for each graphics task I insert in the retrace queue. By some unknown means each task has associated with it a "dark band" in which its image does not appear on the screen. Each band is horizontally oriented and is about 20 pixels wide. Each of the bands for each task is seperate from the others, and each band stays in approximately the same location for the duration of the program. Does anyone out there fool around with this kind of stuff? And if so, do the symptoms sound familiar? I am not using QuickDraw, I am twiddling bits by standard methods. My graphics routines seem to work fine for static displays, and flicker and jitter when I animate without using the Vinstall() and VRemove() calls. With the calls I get "bands". Advice and LSC source code are more than welcome. Kevin T. Rowney krowney@math.ucla.edu