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i965/msaa: Expand odd-sized MSAA surfaces to account for interleaving pattern.

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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.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
This commit is contained in:
Paul Berry
2012-05-10 17:52:09 -07:00
parent 93594f38be
commit 52fcc36f11
1 changed files with 40 additions and 5 deletions
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src/mesa/drivers/dri/intel/intel_mipmap_tree.c
+40 -5
View File
@@ -261,15 +261,50 @@ intel_miptree_create_for_renderbuffer(struct intel_context *intel,
{
struct intel_mipmap_tree *mt;
/* Adjust width/height for MSAA */
/* Adjust width/height for MSAA.
*
* In the Sandy Bridge PRM, volume 4, part 1, page 31, it says:
*
* "Any of the other messages (sample*, LOD, load4) used with a
* (4x) multisampled surface will in-effect sample a surface with
* double the height and width as that indicated in the surface
* state. Each pixel position on the original-sized surface is
* replaced with a 2x2 of samples with the following arrangement:
*
* sample 0 sample 2
* sample 1 sample 3"
*
* Thus, when sampling from a multisampled texture, it behaves as though
* the layout in memory for (x,y,sample) is:
*
* (0,0,0) (0,0,2) (1,0,0) (1,0,2)
* (0,0,1) (0,0,3) (1,0,1) (1,0,3)
*
* (0,1,0) (0,1,2) (1,1,0) (1,1,2)
* (0,1,1) (0,1,3) (1,1,1) (1,1,3)
*
* However, the actual layout of multisampled data in memory is:
*
* (0,0,0) (1,0,0) (0,0,1) (1,0,1)
* (0,1,0) (1,1,0) (0,1,1) (1,1,1)
*
* (0,0,2) (1,0,2) (0,0,3) (1,0,3)
* (0,1,2) (1,1,2) (0,1,3) (1,1,3)
*
* This pattern repeats for each 2x2 pixel block.
*
* As a result, when calculating the size of our 4-sample buffer for
* an odd width or height, we have to align before scaling up because
* sample 3 is in that bottom right 2x2 block.
*/
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,