gallium: add support for programmable sample locations

Signed-off-by: Rhys Perry <[email protected]>
Reviewed-by: Brian Paul <[email protected]> (v2)
Reviewed-by: Marek Olšák <[email protected]> (v2)

4 files changed, 52 insertions, 2 deletions

diff --git a/src/gallium/include/pipe/p_context.h b/src/gallium/include/pipe/p_context.h
index c3dc5edf57d..7cf037f1abd 100644
--- a/src/gallium/include/pipe/p_context.h
+++ b/src/gallium/include/pipe/p_context.h
@@ -279,8 +279,35 @@ struct pipe_context {
    void (*set_framebuffer_state)( struct pipe_context *,
                                   const struct pipe_framebuffer_state * );
 
+   /**
+    * Set the sample locations used during rasterization. When NULL or sized
+    * zero, the default locations are used.
+    *
+    * Note that get_sample_position() still returns the default locations.
+    *
+    * The samples are accessed with
+    * locations[(pixel_y*grid_w+pixel_x)*ms+i],
+    * where:
+    * ms      = the sample count
+    * grid_w  = the pixel grid width for the sample count
+    * grid_w  = the pixel grid height for the sample count
+    * pixel_x = the window x coordinate modulo grid_w
+    * pixel_y = the window y coordinate modulo grid_w
+    * i       = the sample index
+    * This gives a result with the x coordinate as the low 4 bits and the y
+    * coordinate as the high 4 bits. For each coordinate 0 is the left or top
+    * edge of the pixel's rectangle and 16 (not 15) is the right or bottom edge.
+    *
+    * Out of bounds accesses are return undefined values.
+    *
+    * The pixel grid is used to vary sample locations across pixels and its
+    * size can be queried with get_sample_pixel_grid().
+    */
+   void (*set_sample_locations)( struct pipe_context *,
+                                 size_t size, const uint8_t *locations );
+
    void (*set_polygon_stipple)( struct pipe_context *,
-				const struct pipe_poly_stipple * );
+                                const struct pipe_poly_stipple * );
 
    void (*set_scissor_states)( struct pipe_context *,
                                unsigned start_slot,
@@ -485,6 +512,16 @@ struct pipe_context {
                         int clear_value_size);
 
    /**
+    * If a depth buffer is rendered with different sample location state than
+    * what is current at the time of reading, the values may differ because
+    * depth buffer compression can depend the sample locations.
+    *
+    * This function is a hint to decompress the current depth buffer to avoid
+    * such problems.
+    */
+   void (*evaluate_depth_buffer)(struct pipe_context *pipe);
+
+   /**
     * Flush draw commands.
     *
     * This guarantees that the new fence (if any) will finish in finite time,
@@ -720,7 +757,7 @@ struct pipe_context {
    /*@}*/
 
    /**
-    * Get sample position for an individual sample point.
+    * Get the default sample position for an individual sample point.
     *
     * \param sample_count - total number of samples
     * \param sample_index - sample to get the position values for
diff --git a/src/gallium/include/pipe/p_defines.h b/src/gallium/include/pipe/p_defines.h
index 6cc73a31bfc..43db9f8fbaa 100644
--- a/src/gallium/include/pipe/p_defines.h
+++ b/src/gallium/include/pipe/p_defines.h
@@ -813,6 +813,7 @@ enum pipe_cap
    PIPE_CAP_CONSERVATIVE_RASTER_PRE_SNAP_POINTS_LINES,
    PIPE_CAP_MAX_CONSERVATIVE_RASTER_SUBPIXEL_PRECISION_BIAS,
    PIPE_CAP_CONSERVATIVE_RASTER_POST_DEPTH_COVERAGE,
+   PIPE_CAP_PROGRAMMABLE_SAMPLE_LOCATIONS,
 };
 
 /**
diff --git a/src/gallium/include/pipe/p_screen.h b/src/gallium/include/pipe/p_screen.h
index 8fd81a4e9a9..0439060b606 100644
--- a/src/gallium/include/pipe/p_screen.h
+++ b/src/gallium/include/pipe/p_screen.h
@@ -132,6 +132,17 @@ struct pipe_screen {
 			    void *ret);
 
    /**
+    * Get the sample pixel grid's size. This function requires
+    * PIPE_CAP_PROGRAMMABLE_SAMPLE_LOCATIONS to be callable.
+    *
+    * \param sample_count - total number of samples
+    * \param out_width - the width of the pixel grid
+    * \param out_height - the height of the pixel grid
+    */
+   void (*get_sample_pixel_grid)(struct pipe_screen *, unsigned sample_count,
+                                 unsigned *out_width, unsigned *out_height);
+
+   /**
     * Query a timestamp in nanoseconds. The returned value should match
     * PIPE_QUERY_TIMESTAMP. This function returns immediately and doesn't
     * wait for rendering to complete (which cannot be achieved with queries).
diff --git a/src/gallium/include/pipe/p_state.h b/src/gallium/include/pipe/p_state.h
index db9fa1a8e9f..809aa087ce0 100644
--- a/src/gallium/include/pipe/p_state.h
+++ b/src/gallium/include/pipe/p_state.h
@@ -74,6 +74,7 @@ extern "C" {
 #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
+#define PIPE_MAX_SAMPLE_LOCATION_GRID_SIZE 4
 
 #define PIPE_MAX_HW_ATOMIC_BUFFERS 32