double buffer manipulation
Author
hallo everyone..
how does one go about to manipulate the render outputted to a buffer (as I suppose that it is?).. say that you wanna set the red channel to 255 post-render, before you display it?
any help would be greatly appreciated. thanks.
Author
is it possible to fill the buffer with something before the render? (apart from sett the glClearColor of course)..
well you can render a fullscreen texture instead glclear
With best regards,
Mirek Czerwiñski
http://kris.top.pl/~kherin/
With best regards,
Mirek Czerwiñski
http://kris.top.pl/~kherin/
Three ways.
1. Render through DirectDraw. This way you can change any pixel of any color. You lose cross-platform compatibility, though.
2. If you''re clearing the screen with one color you can just render a quad onto the screen w/ no lighting.
3. I''m not sure this would work, but if it does it might be useful. If you want to change one or two pixels at a time, then just use glOrtho and render one quad per pixel. Of course, the more pixels you have to cover, the slower it runs.
I haven''t done it personally, but can''t you change the gamma of a card so that it''s redder or bluer or greener or something like that?
1. Render through DirectDraw. This way you can change any pixel of any color. You lose cross-platform compatibility, though.
2. If you''re clearing the screen with one color you can just render a quad onto the screen w/ no lighting.
3. I''m not sure this would work, but if it does it might be useful. If you want to change one or two pixels at a time, then just use glOrtho and render one quad per pixel. Of course, the more pixels you have to cover, the slower it runs.
I haven''t done it personally, but can''t you change the gamma of a card so that it''s redder or bluer or greener or something like that?
i havent used this so i dont know if thisll work
but look up glPixelMap..(...)
you prolly want to use GL_PIXEL_MAP_R_TO_R make all the R(ed) entrys 255 and hopefully all red will be at 255
another very simple method would be to draw a fullscreen quad over the scene
glColorMask( true, false, false, false )
glColor4f( 1,1,1,1);
glBlendFunc( one, one )
but look up glPixelMap..(...)
you prolly want to use GL_PIXEL_MAP_R_TO_R make all the R(ed) entrys 255 and hopefully all red will be at 255
another very simple method would be to draw a fullscreen quad over the scene
glColorMask( true, false, false, false )
glColor4f( 1,1,1,1);
glBlendFunc( one, one )
Author
thanks for all the replies.. though I don''t really want to specifically change the red channel, that was just an example, what I really need is a pointer to a (hopefully existing 
) linear frame buffer so that I can make 2d effects blended over the 3d stuff..
gph-gw: how do I render through directDraw?
) linear frame buffer so that I can make 2d effects blended over the 3d stuff..gph-gw: how do I render through directDraw?
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