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. You can also drop support for 16-bit formats. What about rendering to R16F, RG16F, and RGBA16F? Does R16F have to be coupled with a 16-bit depth buffer too? Marek _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
