[Mesa-dev] [RFC PATCH] gallium: add interface for advanced MSAA

Nicolai Hähnle nhaehnle at gmail.com
Thu May 24 08:11:31 UTC 2018


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

I like it, but you probably want to be explicit about what happens with 
multiple color attachments, both for samples and for storage samples.

Cheers,
Nicolai


>   * ``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_samples``.
> +
>   **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 */
> 


-- 
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.


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