[Mesa-dev] [PATCH v4] gallium: add API for setting window rectangles

[Nicolai Hähnle]

FYI, in case you haven't heard: the corresponding hardware feature on 
Radeon allows four rectangles, and specifying an arbitrary logic 
function over them. That is, there are 2^4 = 16 bits specifying when 
fragments are discarded.

If we wanted to expose that at some point, we'd have to uglify the 
interface somehow, but that's not really relevant at this point.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>

On 16.06.2016 02:24, Ilia Mirkin wrote:
> Window rectangles apply to all framebuffer operations, either in
> inclusive or exclusive mode. They may also be specified as part of a
> blit operation.
>
> In exclusive mode, any fragment inside any of the specified rectangles
> will be discarded.
>
> In inclusive mode, any fragment outside every rectangle will be
> discarded.
>
> The no-op state is to have 0 rectangles in exclusive mode.
>
> Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
> ---
>
> v3 -> v4:
>    - make it clearer that clears aren't affected by window rectangles.
>    - rename context call to ->set_window_rectangles
>
>   src/gallium/docs/source/context.rst  | 17 ++++++++++++++---
>   src/gallium/include/pipe/p_context.h |  5 +++++
>   src/gallium/include/pipe/p_state.h   |  6 ++++++
>   3 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/src/gallium/docs/source/context.rst b/src/gallium/docs/source/context.rst
> index 3a45f40..6f09c55 100644
> --- a/src/gallium/docs/source/context.rst
> +++ b/src/gallium/docs/source/context.rst
> @@ -79,6 +79,17 @@ objects. They all follow simple, one-method binding calls, e.g.
>     should be the same as the number of set viewports and can be up to
>     PIPE_MAX_VIEWPORTS.
>   * ``set_viewport_states``
> +* ``set_window_rectangles`` sets the window rectangles to be used for
> +  rendering, as defined by GL_EXT_window_rectangles. There are two
> +  modes - include and exclude, which define whether the supplied
> +  rectangles are to be used for including fragments or excluding
> +  them. All of the rectangles are ORed together, so in exclude mode,
> +  any fragment inside any rectangle would be culled, while in include
> +  mode, any fragment outside all rectangles would be culled. xmin/ymin
> +  are inclusive, while xmax/ymax are exclusive (same as scissor states
> +  above). Note that this only applies to draws, not clears or
> +  blits. (Blits have their own way to pass the requisite rectangles
> +  in.)
>   * ``set_tess_state`` configures the default tessellation parameters:
>     * ``default_outer_level`` is the default value for the outer tessellation
>       levels. This corresponds to GL's ``PATCH_DEFAULT_OUTER_LEVEL``.
> @@ -492,9 +503,9 @@ This can be considered the equivalent of a CPU memcpy.
>
>   ``blit`` blits a region of a resource to a region of another resource, including
>   scaling, format conversion, and up-/downsampling, as well as a destination clip
> -rectangle (scissors). It can also optionally honor the current render condition
> -(but either way the blit itself never contributes anything to queries currently
> -gathering data).
> +rectangle (scissors) and window rectangles. It can also optionally honor the
> +current render condition (but either way the blit itself never contributes
> +anything to queries currently gathering data).
>   As opposed to manually drawing a textured quad, this lets the pipe driver choose
>   the optimal method for blitting (like using a special 2D engine), and usually
>   offers, for example, accelerated stencil-only copies even where
> diff --git a/src/gallium/include/pipe/p_context.h b/src/gallium/include/pipe/p_context.h
> index 9d7a8eb..6fde875 100644
> --- a/src/gallium/include/pipe/p_context.h
> +++ b/src/gallium/include/pipe/p_context.h
> @@ -274,6 +274,11 @@ struct pipe_context {
>                                  unsigned num_scissors,
>                                  const struct pipe_scissor_state * );
>
> +   void (*set_window_rectangles)( struct pipe_context *,
> +                                  boolean include,
> +                                  unsigned num_rectangles,
> +                                  const struct pipe_scissor_state * );
> +
>      void (*set_viewport_states)( struct pipe_context *,
>                                   unsigned start_slot,
>                                   unsigned num_viewports,
> diff --git a/src/gallium/include/pipe/p_state.h b/src/gallium/include/pipe/p_state.h
> index 396f563..9c69355 100644
> --- a/src/gallium/include/pipe/p_state.h
> +++ b/src/gallium/include/pipe/p_state.h
> @@ -69,6 +69,7 @@ extern "C" {
>   #define PIPE_MAX_VIEWPORTS        16
>   #define PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT 8
>   #define PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT 2
> +#define PIPE_MAX_WINDOW_RECTANGLES 8
>
>
>   struct pipe_reference
> @@ -710,6 +711,11 @@ struct pipe_blit_info
>      boolean scissor_enable;
>      struct pipe_scissor_state scissor;
>
> +   /* Window rectangles can either be inclusive or exclusive. */
> +   boolean window_rectangle_include;
> +   unsigned num_window_rectangles;
> +   struct pipe_scissor_state window_rectangles[PIPE_MAX_WINDOW_RECTANGLES];
> +
>      boolean render_condition_enable; /**< whether the blit should honor the
>                                       current render condition */
>      boolean alpha_blend; /* dst.rgb = src.rgb * src.a + dst.rgb * (1 - src.a) */
>