[Mesa-dev] dd_function_table::Clear()

[Brian Paul]

On 01/18/2012 09:01 AM, Dee Sharpe wrote:
> While implementing Clear() for a platform, which buffers in GLContext need to be cleared out of the list of:
>
> DrawBuffer
> ReadBuffer
> WinSysDrawBuffer
> WinSysReadBuffer
>
> Or do they all need to be cleared?

Clearing effects "draw" buffers, not "read" buffers.

Unless a user-created FBO is bound, ctx->WinSysDrawBuffer == 
ctx->DrawBuffer.

You need to clear the color buffers attached to ctx->DrawBuffer.  The 
number of buffers to clear is ctx->DrawBuffer->_NumColorDrawBuffers 
and the indexes/pointers to the renderbuffers is in 
_ColorDrawBufferIndexes[] and _ColorDrawBuffers[].

I may actually get rid of the later (redundant) array and just write a 
helper function that returns a pointer to a renderbuffer given a 
buffer index.

-Brian