----- Original Message ----- > On 12/12/2011 02:49 PM, Jose Fonseca wrote: > > ----- Original Message ----- > >> From: Marek Olšák <mar...@gmail.com> > >> > >> It's like DrawArrays, but the count is taken from a transform > >> feedback > >> object. > >> > >> This removes DrawTransformFeedback from dd_function_table and adds > >> the same > >> function to GLvertexformat (with the function parameters matching > >> GL). > >> > >> The vbo_draw_func callback has a new parameter > >> "struct gl_transform_feedback_object *tfb_vertcount". > >> > >> The rest of the code just validates states and forwards the > >> transform > >> feedback object into vbo_draw_func. > > > > I ventured reviewing this too, and I have a question: the > > unfinished code in master had comments saying > > > > /* > > * Get number of vertices in obj's feedback buffer. > > * Call ctx->Exec.DrawArrays(mode, 0, count); > > */ > > > > which seems simpler than passing the new tfb_vertcount parameter > > everywhere, just for the sake of obtaining count, so what's the > > rationale for doing this differently here? > > > > The count is "contained" in the TFB object (through its association > with > a pipe_stream_output_target which tracks the amount of vertices > written > to it) and is not supposed to be read back by the CPU because that > would > mean waiting. > > The driver will let the GPU write the count into the command buffer, > so > it only needs to sync command processing with TFB.
I see. Makes sense. I have no more objections against the series FWIW. It would be nice to fix softpipe/llvmpipe though, but IIUC they could not possibly have worked with Mesa before, and I don't think anybody is relying on that softpipe/llvmpipe functionality w/ other state trackers at this point, so I suppose it could wait. Jose _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
