[Mesa3d-dev] Framebuffers in mesa

[Maciej C. <m.c...@gm...>]

Hi all,

I've got some questions regarding FBOs in mesa. I hope you'll be able to 
answer at least some of them.

GLcontext structure holds pointers to 4 gl_framebuffers (DrawBuffer, ReadBuffer, 
WinSysDrawBuffer, WinSysReadBuffer) and one to gl_renderbuffer 
(CurrentRenderbuffer). gl_framebuffer struct contains amongs other fields:
_ColorDrawBuffers[], _ColorReadBuffers, _DepthBuffer, _StencilBuffer.
Now having in mind that r300 wraps all gl_renderbuffers and gl_texture_object 
(they contain HW buffer objects that I'm interested in), what is the proper way 
to get to read and draw buffers?

What operations use ctx->_ReadBuffer besides glReadPixels,glCopyPixels and 
glCopyTex(Sub)Image?

What operations use ctx->_DrawBuffer besides rendering operations? 
(glBegin/glEnd, glDrawElements, glDrawArrays, ...)

Am I correct that for ctx->_DrawBuffer field _ColorReadBuffer is unused, and for 
ctx->_ReadBuffer _ColorDrawBuffers is unused?

Regards,
Maciej