gallium: add API for setting window rectangles

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@alum.mit.edu>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

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

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,

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) */