<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Tue, May 1, 2018 at 10:48 AM, Roland Scheidegger <<a href="mailto:sroland@vmware.com" target="_blank">sroland@vmware.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Am 01.05.2018 um 01:43 schrieb Marek Olšák: > From: Marek Olšák <<a href="mailto:marek.olsak@amd.com">marek.olsak@amd.com</a>> > > This is a hypothetical interface for EQAA (a superset of CSAA). CSAA could be > exposed via GL_NV_framebuffer_multisample_coverage. EQAA additionally removes > the restriction that the number of samples in all FBO attachments must match, > which means it allows arbitrary sample counts in each FBO attachment. The idea sounds ok to me, as long as you don't expose the additional modes with more samples as ordinary msaa modes. (I'm quite sure at some point nvidia exposed 16x msaa modes through ordinary means, which then gave you really 4 color samples and 12 coverage-only samples, in some not-very-compliant way. Though IIRC the extension is actually older than the ability to do per-sample msaa fb reads, so it wasn't as problematic back then.) > --- > src/gallium/docs/source/screen.rst | 17 +++++++++++++++-- > src/gallium/include/pipe/p_defines.h | 1 + > src/gallium/include/pipe/p_state.h | 3 ++- > 3 files changed, 18 insertions(+), 3 deletions(-) > > diff --git a/src/gallium/docs/source/screen.rst b/src/gallium/docs/source/screen.rst > index 3837360fb40..28934c2f7b9 100644 > --- a/src/gallium/docs/source/screen.rst > +++ b/src/gallium/docs/source/screen.rst > @@ -398,20 +398,22 @@ The integer capabilities: > * ``PIPE_CAP_LOAD_CONSTBUF``: True if the driver supports TGSI_OPCODE_LOAD use > with constant buffers. > * ``PIPE_CAP_TGSI_ANY_REG_AS_ADDRESS``: Any TGSI register can be used as > an address for indirect register indexing. > * ``PIPE_CAP_TILE_RASTER_ORDER``: Whether the driver supports > GL_MESA_tile_raster_order, using the tile_raster_order_* fields in > pipe_rasterizer_state. > * ``PIPE_CAP_MAX_COMBINED_SHADER_OUTPUT_RESOURCES``: Limit on combined shader > output resources (images + buffers + fragment outputs). If 0 the state > tracker works it out. > +* ``PIPE_CAP_EQAA_COLOR_SAMPLE_SUPPORT_MASK``: If the i-th bit is set, EQAA > + supports (i+1) color samples. I agree with Nicolai here, this looks strange, this should instead query for total samples or something. > * ``PIPE_CAP_SIGNED_VERTEX_BUFFER_OFFSET``: > Whether pipe_vertex_buffer::buffer_offset is treated as signed. The u_vbuf > module needs this for optimal performance in workstation applications. > * ``PIPE_CAP_CONTEXT_PRIORITY_MASK``: For drivers that support per-context > priorities, this returns a bitmask of PIPE_CONTEXT_PRIORITY_x for the > supported priority levels. A driver that does not support prioritized > contexts can return 0. > * ``PIPE_CAP_FENCE_SIGNAL``: True if the driver supports signaling semaphores > using fence_server_signal(). > * ``PIPE_CAP_CONSTBUF0_FLAGS``: The bits of pipe_resource::flags that must be > @@ -743,22 +745,33 @@ Modern APIs allow using buffers as shader resources. > (1 for 1D or 1D array textures). > > **depth0** the depth of the base mip level of the texture > (1 for everything else). > > **array_size** the array size for 1D and 2D array textures. > For cube maps this must be 6, for other textures 1. > > **last_level** the last mip map level present. > > -**nr_samples** the nr of msaa samples. 0 (or 1) specifies a resource > -which isn't multisampled. > +**nr_samples**: For Z/S, this is the number of samples. For color, if EQAA > +is unsupported, this is the number of both coverage samples and color samples. > +If EQAA is supported, this is the number of coverage samples. 0 and 1 > +specify a resource which isn't multisampled. I think you should keep nr_samples alone, and re-change the meaning to actually be "real" samples with all associated data (which is what everybody expects with msaa). > + > +**nr_color_samples**: This is the number of color samples for EQAA, while > +``nr_samples`` is the number of coverage samples. If the format is Z/S, > +``nr_color_samples`` is ignored. Constraints: > +* ``nr_color_samples`` must not be greater than ``nr_samples``. > +* If ``nr_color_samples`` is equal to ``nr_samples``, it is called MSAA. > +* If ``nr_color_samples`` is less than ``nr_samples``, it is called EQAA. > +* If ``nr_color_samples`` is equal to 1, the behavior of the resolve blit is > +driver-dependent. > Hence instead use something like "total_samples" or "coverage samples" here (albeit the latter could be a bit confusing, unclear if it means all samples or just the extra ones). If you'd use something like "number of additional coverage samples" instead, then you could even leave all state trackers alone, since 0 would automatically mean ordinary msaa without crazy stuff. And fwiw I'd stick to the CSAA name - coverage at least has some meaning, whereas "enhanced" (which is what the "E" in EQAA is for according to some old articles) really is just completely meaningless marketing term. There really isn't any difference, ok the ability to use different amount of samples per rt might be something, but you can't expose this anyway (AMD didn't come up with an extension for this since the 7+ years it's supported (since NI), so I have some doubts of its usefulness - besides you could have another cap which then would say if that's valid or not if you really come up with an extension specifically for it.) Unless there's some non-technical reasons you can't use the term CSAA. </blockquote><div> </div><div>EQAA is a superset of CSAA and is more complicated, so it doesn't make sense to use "CSAA". </div><div>Marek </div></div> </div></div>