On Tue, Feb 4, 2014 at 9:06 PM, Roland Scheidegger <srol...@vmware.com> wrote: > Am 04.02.2014 13:19, schrieb Marek Olšák: >> On Tue, Feb 4, 2014 at 10:29 AM, Rogovin, Kevin <kevin.rogo...@intel.com> >> wrote: >>> >>> >>>> I don't believe our hardware can support GL_ARB_shader_stencil_export. >>>> The render target write message can take RGBA, depth, and sample masks, >>>> but not stencil. Without that, it's not at all obvious how to implement >>>> it. >>> >>> There is a terrible hack-ish way to do it, but I stress the word terrible >>> and hackish and >>> it may not work correctly depending on the tile modes and all that fun. >>> >>> Here goes. Assuming the depth-stencil is D24S8 we can do this and that the >>> tile modes work out: >>> >>> Bind src depth-stencil as RGBA_8UI, the depth should be in RGB and the >>> stencil in A. >>> Bind the dst depth-stencil as RGBA_8UI as well. Fragment shader is simple >>> unfiltered >>> read and write to dest. If not writing to depth or stencil, mask our RGB or >>> A respectively. >>> >>> The above does not handle MSAA->non-MSAA. Going further, it can be done in >>> general >>> on *paper* with GL_ARB_texture_view if that is extended to allow D24S8 to >>> be on the same >>> castable category as RGBA_8UI. The main catch is how the tile modes work >>> out, i.e. if the >>> tile mode for a D24S8 is "compatible" with a RGBA_8UI render target. >> >> This is how r300g does it. It blits D24S8 as RGBA_UNORM. Gallium has >> texture views and it has no limitations on how you can change the >> format, so it's pretty trivial. r300g changes the format, then calls >> our "meta" code (u_blitter). >> > > It is not actually obvious this is something which should work in > gallium in that way. The docs say the format must be "compatible" > without saying much else (obviously, same number of block bits is a > requirement). u_format has some function which would check if formats > are compatible (albeit for a different purpose) and it wouldn't consider > your example compatible. > The intention of sampler views is it should allow casting allowed by the > APIs (d3d10, whatever GL extension). > The definition of this is definitely loose.
Yeah, it's not very well defined, but that's not important, because r300g changes the format *internally*, because it knows it can do that. Marek _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
