On Tue, May 20, 2014 at 11:04 PM, Ilia Mirkin <imir...@alum.mit.edu> wrote: > On Tue, May 20, 2014 at 4:51 PM, Marek Olšák <mar...@gmail.com> wrote: >> On Tue, May 20, 2014 at 9:58 PM, Ilia Mirkin <imir...@alum.mit.edu> wrote: >>> Hello, >>> >>> I attempted doing this a while back, before I really understood what >>> was going on. I got some advice that went totally over my head, and I >>> dropped the issue. I think I'm much better-prepared to tackle the >>> issue this time around. >>> >>> To recap, nv30 (and nv40) hw can't handle certain color/depth format >>> combinations. Specifically, a 16-bit color format must be paired with >>> a 16-bit depth format, and a 32-bit color format must be paired with a >>> 32-bit depth format (well, Z24S8). This HW also can't handle different >>> per-attachment sizes, and also the "linearity" of all the attachments >>> must be the same. (Whether a surface is linear or not is _generally_ >>> dictated by its w/h, but not always -- POT textures can sometimes end >>> up allocated linearly by e.g. the ddx, or something else.) The >>> different sizes are handled by not exposing ARB_fbo. However the rest >>> of the cases remain. >>> >>> Now that I kinda understand how things are structured, I was thinking >>> of doing the following: >>> >>> When rendering (i.e. draw_vbo & co) and the fbo has changed (and has >>> one of the problems above), I would instead put in a temporary texture >>> as the depth attachment. Before actually drawing, I would blit from >>> the real target texture into the temporary texture, and then when >>> rendering is done, blit back from the temp texture back into the >>> target. This deals with the target texture getting modified between >>> draws with various blits/mapping/whatever. >>> >>> This means that you'll only get 16 bits of depth even if you ask for >>> 24 with a 16-bit color format, but the alternative seems too >>> complex/costly. >>> >>> So there are a few questions from this approach: >>> >>> 1. Where do I get the temporary texture from? (And more importantly -- >>> when... what happens if allocation fails?) >>> >>> 2. Having to blit the depth texture back and forth on every draw seems >>> _really_ wasteful... anything I can do about that? >> >> You can do that in set_framebuffer_state. When binding, blit to a >> depth buffer which matches the colorbuffer format. When unbinding, >> blit back. > > set_framebuffer_state doesn't allow an error to be returned. Should I > just print a warning and move on?
Yes, because you have no other choice. > > I guess I'm still not 100% on all the terminology -- what do you mean > exactly by bind/unbind? Do you mean the transfer_map/unmap stuff? So > basically I would blit once on set_framebuffer_state, and then blit > back and forth on resource map/unmap, and only ever render to the > "temporary" buffer without worrying about blitting wihle rendering? "bind" is when a buffer is set, "unbind" is when the buffer is unset. set_framebuffer_state unbinds the current framebuffer and binds a new one. transfer_map/unmap must use the resource which contains the latest data, there is no doubt about that. If there are no transfers, you only have to do the blits between 32-bit and 16-bit in set_framebuffer_state, because that's the only place where the framebuffer is changed. Marek _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
