[Mesa-dev] [PATCH 01/15] i965/msaa: Expand odd-sized MSAA surfaces to account for interleaving pattern.

[Paul Berry]

Gen6 MSAA buffers (and Gen7 MSAA depth/stencil buffers) interleave
MSAA samples in a complex pattern that repeats every 2x2 pixel block.
Therefore, when allocating an MSAA buffer, we need to make sure to
allocate an integer number of 2x2 blocks; if we don't, then some of
the samples in the last row and column will be cut off.

Fixes piglit tests "EXT_framebuffer_multisample/unaligned-blit {2,4}
color msaa" on i965/Gen6.
---
 src/mesa/drivers/dri/intel/intel_mipmap_tree.c |   15 ++++++++++-----
 1 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/mesa/drivers/dri/intel/intel_mipmap_tree.c b/src/mesa/drivers/dri/intel/intel_mipmap_tree.c
index 99f4230..36d7b77 100644
--- a/src/mesa/drivers/dri/intel/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/intel/intel_mipmap_tree.c
@@ -261,15 +261,20 @@ intel_miptree_create_for_renderbuffer(struct intel_context *intel,
 {
    struct intel_mipmap_tree *mt;
 
-   /* Adjust width/height for MSAA */
+   /* Adjust width/height for MSAA.  Note: since samples are interleaved in a
+    * complex pattern that repeats for every 2x2 block of pixels, we need to
+    * expand the width and height to even numbers before the width/height
+    * adjustment, otherwise some of the samples in the last row and column
+    * will fall outside the boundary of the texture.
+    */
    if (num_samples > 4) {
       num_samples = 8;
-      width *= 4;
-      height *= 2;
+      width = ALIGN(width, 2) * 4;
+      height = ALIGN(height, 2) * 2;
    } else if (num_samples > 0) {
       num_samples = 4;
-      width *= 2;
-      height *= 2;
+      width = ALIGN(width, 2) * 2;
+      height = ALIGN(height, 2) * 2;
    }
 
    mt = intel_miptree_create(intel, GL_TEXTURE_2D, format, 0, 0,
-- 
1.7.7.6