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i965/msaa: Adjust 3DSTATE_MULTISAMPLE packet for 8x MSAA.

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Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Paul Berry 2012-07-17 21:06:01 -07:00
parent 7fae97c98b
commit 2a9ab29ed9
1 changed files with 64 additions and 6 deletions
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70
src/mesa/drivers/dri/i965/gen6_multisample_state.c
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@ -36,17 +36,75 @@ gen6_emit_3dstate_multisample(struct brw_context *brw,
{
struct intel_context *intel = &brw->intel;
/* TODO: 8x MSAA not implemented */
assert(num_samples <= 4);
uint32_t number_of_multisamples = 0;
uint32_t sample_positions_3210 = 0;
uint32_t sample_positions_7654 = 0;
switch (num_samples) {
case 0:
number_of_multisamples = MS_NUMSAMPLES_1;
break;
case 4:
number_of_multisamples = MS_NUMSAMPLES_4;
/* Sample positions:
* 2 6 a e
* 2 0
* 6 1
* a 2
* e 3
*/
sample_positions_3210 = 0xae2ae662;
break;
case 8:
number_of_multisamples = MS_NUMSAMPLES_8;
/* Sample positions are based on a solution to the "8 queens" puzzle.
* Rationale: in a solution to the 8 queens puzzle, no two queens share
* a row, column, or diagonal. This is a desirable property for samples
* in a multisampling pattern, because it ensures that the samples are
* relatively uniformly distributed through the pixel.
*
* There are several solutions to the 8 queens puzzle (see
* http://en.wikipedia.org/wiki/Eight_queens_puzzle). This solution was
* chosen because it has a queen close to the center; this should
* improve the accuracy of centroid interpolation, since the hardware
* implements centroid interpolation by choosing the centermost sample
* that overlaps with the primitive being drawn.
*
* Note: from the Ivy Bridge PRM, Vol2 Part1 p304 (3DSTATE_MULTISAMPLE:
* Programming Notes):
*
* "When programming the sample offsets (for NUMSAMPLES_4 or _8 and
* MSRASTMODE_xxx_PATTERN), the order of the samples 0 to 3 (or 7
* for 8X) must have monotonically increasing distance from the
* pixel center. This is required to get the correct centroid
* computation in the device."
*
* Sample positions:
* 1 3 5 7 9 b d f
* 1 5
* 3 2
* 5 6
* 7 4
* 9 0
* b 3
* d 1
* f 7
*/
sample_positions_3210 = 0xdbb39d79;
sample_positions_7654 = 0x3ff55117;
break;
default:
assert(!"Unrecognized num_samples in gen6_emit_3dstate_multisample");
break;
}
int len = intel->gen >= 7 ? 4 : 3;
BEGIN_BATCH(len);
OUT_BATCH(_3DSTATE_MULTISAMPLE << 16 | (len - 2));
OUT_BATCH(MS_PIXEL_LOCATION_CENTER |
(num_samples > 0 ? MS_NUMSAMPLES_4 : MS_NUMSAMPLES_1));
OUT_BATCH(num_samples > 0 ? 0xae2ae662 : 0); /* positions for 4/8-sample */
OUT_BATCH(MS_PIXEL_LOCATION_CENTER | number_of_multisamples);
OUT_BATCH(sample_positions_3210);
if (intel->gen >= 7)
OUT_BATCH(0);
OUT_BATCH(sample_positions_7654);
ADVANCE_BATCH();
}