Ok, here goes, Ive been working on a winamp vis plugin (makes pictures to music basically ;-) and I need to know how I can dim the whole screen's alpha by a small amount and draw over it... (Im not clearing the color buffer bit thingy)... Ive tried blending a big black square... but it just flickers alot... Any insight would be appreciated... (this is for motion blur *typo grin* ) Edited by - Beyonddeath on September 18, 2001 11:41:51 PM

try using the accumulation buffer for motion blur.
it might be slow though since video cards don''t support it(to my knowledge)

Ill look into that thanks allot

This is really really slow... and doesnt exactly work... it just gives me 2 fps and looks really weird on all the textures...

anyway... is there any other way to do it? I was getting 100fps before that accumulation buffer... so ya its not really useful...


Thanks again

I''m not sure I understand what you mean by "dim the alpha and draw over it". You mentioned flickering, which sounds like rather than clearing the screen and redrawing completely, you''re interested in keeping the old image visible and just slowly fading it and adding new info -- very much in-line with a winamp plugin.

If that is correct, then I assume the flickering you see is related to double buffering. You''re drawing to the old front buffer which is officially undefined after a swp to the back buffer. Presumably if a swap truly does a swap, then it''s out of sync with the other buffer. You can verify this by simply using single buffer mode. It may be that''s your best option.

I could swear I read someplace that you can get the swapbuffer call to do a copy and leave the old buffer alone so that you''ve got two identical buffers, but I can''t recall where I think I saw this. You might look into a glCopyPixels call to move your pixels from the back buffer to front buffer ans skip the swapbuffers call, but I dunno how fast that''d be. Since it''s all in the card, it has the potential to be very fast (fast as a swap I would think)...

Thanks allot... Ill try that tonight if i get time...