Can you not render to a texture buffer? That might not be supported by nv30 actually.
On Tue, May 20, 2014 at 8:49 PM, Marek Olšák <mar...@gmail.com> wrote: > ARB_buffer_storage doesn't have anything to do with framebuffers. > > Marek > > On Wed, May 21, 2014 at 2:27 AM, Ilia Mirkin <imir...@alum.mit.edu> wrote: >> On Tue, May 20, 2014 at 6:20 PM, Marek Olšák <mar...@gmail.com> wrote: >>> 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. >> >> OK, I see. That makes sense, I think. So I just have to be careful >> with the transfers to make sure to blit things back first (or maybe I >> don't even have to do that, haven't checked the transfer api), similar >> for blit. And I'll need to turn off ARB_buffer_storage. >> >> -ilia _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
