2 files changed, 35 insertions, 0 deletions
diff --git a/src/gallium/auxiliary/util/u_framebuffer.c b/src/gallium/auxiliary/util/u_framebuffer.c
index c2948a5cfb3..5bafddc726f 100644
--- a/src/gallium/auxiliary/util/u_framebuffer.c
+++ b/src/gallium/auxiliary/util/u_framebuffer.c
@@ -240,3 +240,33 @@ util_framebuffer_get_num_samples(const struct pipe_framebuffer_state *fb)
 
    return 1;
 }
+
+
+/**
+ * Flip the sample location state along the Y axis.
+ */
+void
+util_sample_locations_flip_y(struct pipe_screen *screen, unsigned fb_height,
+                             unsigned samples, uint8_t *locations)
+{
+   unsigned row, i, shift, grid_width, grid_height;
+   uint8_t new_locations[
+      PIPE_MAX_SAMPLE_LOCATION_GRID_SIZE *
+      PIPE_MAX_SAMPLE_LOCATION_GRID_SIZE * 32];
+
+   screen->get_sample_pixel_grid(screen, samples, &grid_width, &grid_height);
+
+   shift = fb_height % grid_height;
+
+   for (row = 0; row < grid_height; row++) {
+      unsigned row_size = grid_width * samples;
+      for (i = 0; i < row_size; i++) {
+         unsigned dest_row = grid_height - row - 1;
+         /* this relies on unsigned integer wraparound behaviour */
+         dest_row = (dest_row - shift) % grid_height;
+         new_locations[dest_row * row_size + i] = locations[row * row_size + i];
+      }
+   }
+
+   memcpy(locations, new_locations, grid_width * grid_height * samples);
+}
diff --git a/src/gallium/auxiliary/util/u_framebuffer.h b/src/gallium/auxiliary/util/u_framebuffer.h
index c73942c9c14..877e6e393f7 100644
--- a/src/gallium/auxiliary/util/u_framebuffer.h
+++ b/src/gallium/auxiliary/util/u_framebuffer.h
@@ -64,6 +64,11 @@ extern unsigned
 util_framebuffer_get_num_samples(const struct pipe_framebuffer_state *fb);
 
 
+extern void
+util_sample_locations_flip_y(struct pipe_screen *screen, unsigned fb_height,
+                             unsigned samples, uint8_t *locations);
+
+
 #ifdef __cplusplus
 }
 #endif