[Mesa-dev] [RFC PATCH] gallium: add interface for advanced MSAA
Marek Olšák
maraeo at gmail.com
Tue May 22 00:46:39 UTC 2018
Your understanding is correct. I misunderstood CSAA. So it looks like that
CSAA is more useless than I thought. You get the coverage-samples level of
quality for back-to-front rendering, but you may get the depth-samples
level of quality for front-to-back rendering, because "edges" generated by
depth test failures have the same quality as the number of depth samples
(if depth values are uncompressed). AMD supports that mode too, but I don't
recommend using it because of the possible decrease in front-to-back
rendering quality.
The way the CAP is defined doesn't actually allow NV's implementation of
CSAA. A new CAP would be needed.
We'll add a new GL extension for advanced MSAA. The NV extension is
unusable, because it changes GL behavior in a non-backward-compatible way
by allowing storage_samples = 2 for all renderbuffers (which is cheating,
but not surprising from NV).
Marek
On Mon, May 21, 2018 at 12:55 PM, Axel Davy <davyaxel0 at gmail.com> wrote:
> Hi,
>
> I get the impression when looking at online documentation about EQAA and
> CSAA, like
> http://www.nvidia.fr/object/coverage-sampled-aa.html
>
> that the number of stored samples is the same for the color and depth
> buffers.
> Only the samples used for coverage is greater.
>
> With your proposal, isn't the number of samples stored in the depth buffer
> always the same than the number of samples used for coverage ?
> That reduces the use-cases. In nine, we have to enforce the number of
> stored samples to be the same for the color and the depth buffer, but we
> could increase the number of samples used for coverage and enable EQAA/CSAA
> (in fact there is a similar way to advertise the feature for Nvidia and
> Amd).
>
> But maybe I misunderstood.
>
> Yours,
>
> Axel Davy
>
>
> On 18/05/2018 06:05, Marek Olšák wrote:
>
>> From: Marek Olšák <marek.olsak at amd.com>
>>
>> The interface only uses general MSAA terms, so it's "advanced MSAA" and
>> not
>> something vendor-specific.
>>
>> It's a proper subset of EQAA, and a proper superset of CSAA, so it's
>> neither.
>>
>> Changes:
>> - pipe_resource is changed
>> - is_format_supported is changed
>> - a new CAP is added
>> ---
>> src/gallium/docs/source/screen.rst | 31 ++++++++++++++++++++++++++--
>> src/gallium/include/pipe/p_defines.h | 1 +
>> src/gallium/include/pipe/p_screen.h | 1 +
>> src/gallium/include/pipe/p_state.h | 18 +++++++++++++---
>> 4 files changed, 46 insertions(+), 5 deletions(-)
>>
>> diff --git a/src/gallium/docs/source/screen.rst
>> b/src/gallium/docs/source/screen.rst
>> index 5bc6ee99f08..cf4787a1c49 100644
>> --- a/src/gallium/docs/source/screen.rst
>> +++ b/src/gallium/docs/source/screen.rst
>> @@ -398,20 +398,25 @@ 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_FRAMEBUFFER_MIXED_SAMPLES``: Framebuffer attachments can
>> have
>> + different number of samples each with the following restriction:
>> + color.nr_samples >= zs.nr_samples >= color.nr_storage_samples
>> + If 0 is returned, the following restriction applies:
>> + color.nr_samples == zs.nr_samples >= color.nr_storage_samples
>> * ``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
>> @@ -718,20 +723,23 @@ is_format_supported
>> Determine if a resource in the given format can be used in a specific
>> manner.
>> **format** the resource format
>> **target** one of the PIPE_TEXTURE_x flags
>> **sample_count** the number of samples. 0 and 1 mean no multisampling,
>> the maximum allowed legal value is 32.
>> +**storage_sample_count** the number of storage samples. This must be <=
>> +sample_count. See the documentation of ``pipe_resource::nr_storage_sa
>> mples``.
>> +
>> **bindings** is a bitmask of :ref:`PIPE_BIND` flags.
>> Returns TRUE if all usages can be satisfied.
>> can_create_resource
>> ^^^^^^^^^^^^^^^^^^^
>> Check if a resource can actually be created (but don't actually
>> allocate any
>> memory). This is used to implement OpenGL's proxy textures.
>> Typically, a
>> @@ -761,22 +769,41 @@ 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**: Number of samples determining quality, driving the
>> rasterizer,
>> +shading, and framebuffer. It is the number of samples seen by the whole
>> +graphics pipeline. 0 and 1 specify a resource which isn't multisampled.
>> +
>> +**nr_storage_samples**: Only color buffers can set this lower than
>> nr_samples.
>> +Multiple samples within a pixel can have the same color.
>> ``nr_storage_samples``
>> +determines how many slots for different colors there are per pixel.
>> +If there are not enough slots to store all sample colors, some samples
>> will
>> +have an undefined color (called "undefined samples").
>> +
>> +The resolve blit behavior is driver-specific, but can be one of these
>> two:
>> +1. Only defined samples will be averaged. Undefined samples will be
>> ignored.
>> +2. Undefined samples will be approximated by looking at surrounding
>> defined
>> + samples (even in different pixels).
>> +
>> +Blits and MSAA texturing: If the sample being fetched is undefined, one
>> of
>> +the defined samples is returned instead.
>> +
>> +Sample shading (``set_min_samples``) will operate at a sample frequency
>> that
>> +is at most ``nr_storage_samples``. Greater ``min_samples`` values will be
>> +replaced by ``nr_storage_samples``.
>> **usage** one of the :ref:`PIPE_USAGE` flags.
>> **bind** bitmask of the :ref:`PIPE_BIND` flags.
>> **flags** bitmask of PIPE_RESOURCE_FLAG flags.
>> resource_changed
>> diff --git a/src/gallium/include/pipe/p_defines.h
>> b/src/gallium/include/pipe/p_defines.h
>> index 6b2f33b9e37..5693396c9e9 100644
>> --- a/src/gallium/include/pipe/p_defines.h
>> +++ b/src/gallium/include/pipe/p_defines.h
>> @@ -794,20 +794,21 @@ enum pipe_cap
>> PIPE_CAP_ALLOW_MAPPED_BUFFERS_DURING_EXECUTION,
>> PIPE_CAP_POST_DEPTH_COVERAGE,
>> PIPE_CAP_BINDLESS_TEXTURE,
>> PIPE_CAP_NIR_SAMPLERS_AS_DEREF,
>> PIPE_CAP_QUERY_SO_OVERFLOW,
>> PIPE_CAP_MEMOBJ,
>> PIPE_CAP_LOAD_CONSTBUF,
>> PIPE_CAP_TGSI_ANY_REG_AS_ADDRESS,
>> PIPE_CAP_TILE_RASTER_ORDER,
>> PIPE_CAP_MAX_COMBINED_SHADER_OUTPUT_RESOURCES,
>> + PIPE_CAP_FRAMEBUFFER_MIXED_SAMPLES,
>> PIPE_CAP_SIGNED_VERTEX_BUFFER_OFFSET,
>> PIPE_CAP_CONTEXT_PRIORITY_MASK,
>> PIPE_CAP_FENCE_SIGNAL,
>> PIPE_CAP_CONSTBUF0_FLAGS,
>> PIPE_CAP_PACKED_UNIFORMS,
>> PIPE_CAP_CONSERVATIVE_RASTER_POST_SNAP_TRIANGLES,
>> PIPE_CAP_CONSERVATIVE_RASTER_POST_SNAP_POINTS_LINES,
>> PIPE_CAP_CONSERVATIVE_RASTER_PRE_SNAP_TRIANGLES,
>> PIPE_CAP_CONSERVATIVE_RASTER_PRE_SNAP_POINTS_LINES,
>> PIPE_CAP_MAX_CONSERVATIVE_RASTER_SUBPIXEL_PRECISION_BIAS,
>> diff --git a/src/gallium/include/pipe/p_screen.h
>> b/src/gallium/include/pipe/p_screen.h
>> index 101e229088b..94c61dfab2e 100644
>> --- a/src/gallium/include/pipe/p_screen.h
>> +++ b/src/gallium/include/pipe/p_screen.h
>> @@ -150,20 +150,21 @@ struct pipe_screen {
>> /**
>> * Check if the given pipe_format is supported as a texture or
>> * drawing surface.
>> * \param bindings bitmask of PIPE_BIND_*
>> */
>> boolean (*is_format_supported)( struct pipe_screen *,
>> enum pipe_format format,
>> enum pipe_texture_target target,
>> unsigned sample_count,
>> + unsigned storage_sample_count,
>> unsigned bindings );
>> /**
>> * Check if the given pipe_format is supported as output for this
>> codec/profile.
>> * \param profile profile to check, may also be
>> PIPE_VIDEO_PROFILE_UNKNOWN
>> */
>> boolean (*is_video_format_supported)( struct pipe_screen *,
>> enum pipe_format format,
>> enum pipe_video_profile
>> profile,
>> enum pipe_video_entrypoint
>> entrypoint );
>> diff --git a/src/gallium/include/pipe/p_state.h
>> b/src/gallium/include/pipe/p_state.h
>> index db9fa1a8e9f..1baa497b227 100644
>> --- a/src/gallium/include/pipe/p_state.h
>> +++ b/src/gallium/include/pipe/p_state.h
>> @@ -511,41 +511,53 @@ struct pipe_box
>> int16_t depth;
>> };
>> /**
>> * A memory object/resource such as a vertex buffer or texture.
>> */
>> struct pipe_resource
>> {
>> struct pipe_reference reference;
>> - struct pipe_screen *screen; /**< screen that this texture belongs to
>> */
>> unsigned width0; /**< Used by both buffers and textures. */
>> uint16_t height0; /* Textures: The maximum height/depth/array_size
>> is 16k. */
>> uint16_t depth0;
>> uint16_t array_size;
>> enum pipe_format format:16; /**< PIPE_FORMAT_x */
>> enum pipe_texture_target target:8; /**< PIPE_TEXTURE_x */
>> unsigned last_level:8; /**< Index of last mipmap level
>> present/defined */
>> - unsigned nr_samples:8; /**< for multisampled surfaces, nr of
>> samples */
>> - unsigned usage:8; /**< PIPE_USAGE_x (not a bitmask) */
>> + /** Number of samples determining quality, driving rasterizer,
>> shading,
>> + * and framebuffer.
>> + */
>> + unsigned nr_samples:8;
>> +
>> + /** Multiple samples within a pixel can have the same value.
>> + * nr_storage_samples determines how many slots for different values
>> + * there are per pixel. Only color buffers can set this lower than
>> + * nr_samples.
>> + */
>> + unsigned nr_storage_samples:8;
>> +
>> + unsigned usage:8; /**< PIPE_USAGE_x (not a bitmask) */
>> unsigned bind; /**< bitmask of PIPE_BIND_x */
>> unsigned flags; /**< bitmask of PIPE_RESOURCE_FLAG_x */
>> /**
>> * For planar images, ie. YUV EGLImage external, etc, pointer to the
>> * next plane.
>> */
>> struct pipe_resource *next;
>> + /* The screen pointer should be last for optimal structure packing. */
>> + struct pipe_screen *screen; /**< screen that this texture belongs to
>> */
>> };
>> /**
>> * Transfer object. For data transfer to/from a resource.
>> */
>> struct pipe_transfer
>> {
>> struct pipe_resource *resource; /**< resource to transfer to/from */
>> unsigned level; /**< texture mipmap level */
>>
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20180521/b8db80b8/attachment-0001.html>
More information about the mesa-dev
mailing list