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/*
* Copyright © 2013 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <stdint.h>
/**
* 1x MSAA has a single sample at the center: (0.5, 0.5) -> (0x8, 0x8).
*
* 2x MSAA sample positions are (0.25, 0.25) and (0.75, 0.75):
* 4 c
* 4 0
* c 1
*/
static const uint32_t
brw_multisample_positions_1x_2x = 0x0088cc44;
/**
* Sample positions:
* 2 6 a e
* 2 0
* 6 1
* a 2
* e 3
*/
static const uint32_t
brw_multisample_positions_4x = 0xae2ae662;
/**
* 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
*/
static const uint32_t
brw_multisample_positions_8x[] = { 0xdbb39d79, 0x3ff55117 };
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