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

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

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.
---
 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.
 * ``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.
+
+**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.
 
 **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 c4ae0532060..97e1a3a3d42 100644
--- a/src/gallium/include/pipe/p_defines.h
+++ b/src/gallium/include/pipe/p_defines.h
@@ -783,20 +783,21 @@ 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_EQAA_COLOR_SAMPLE_SUPPORT_MASK,
    PIPE_CAP_SIGNED_VERTEX_BUFFER_OFFSET,
    PIPE_CAP_CONTEXT_PRIORITY_MASK,
    PIPE_CAP_FENCE_SIGNAL,
    PIPE_CAP_CONSTBUF0_FLAGS,
    PIPE_CAP_PACKED_UNIFORMS,
 };
 
 /**
  * Possible bits for PIPE_CAP_CONTEXT_PRIORITY_MASK param, which should
  * return a bitmask of the supported priorities.  If the driver does not
diff --git a/src/gallium/include/pipe/p_state.h b/src/gallium/include/pipe/p_state.h
index 4dce399f848..4010b92e67b 100644
--- a/src/gallium/include/pipe/p_state.h
+++ b/src/gallium/include/pipe/p_state.h
@@ -503,41 +503,42 @@ 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 nr_color_samples:8; /**< Number of color samples for EQAA. */
    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;
+   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 */
-- 
2.17.0