hi, what do i need in opengl to render 8 bit
images - with different palettes, for instance i want to in same frame render the bitmap which is
from 8-bit palette index data several times on
different places with different palette.
Unfortunately, paletted textures are not widely supported (i.e. not on any ATI cards) and deprecated on the cards that do support them (i.e. removed from recent nvidia drivers.)
There was a thread on this forum a while ago explaining some of the hardware-level reasons for this, but personally I think it is really stupid that indexed texture colorization during rasterization was never put into the core.
If you’ve got fragment programs, you can implement the lookup yourself, but of course this limits your hardware support pretty severely.
Or you can repeatedly do the mapping during texture upload and conversion to 24bpp, but this is really slow.
Or you can build your own cache system of colorized 24bpp textures, but this eats a ton of VRAM.