src/mesa/drivers/dri/i965/brw_multisample_state.h

   1 /*
   2  * Copyright © 2013 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23
  24 #include <stdint.h>
  25
  26 /**
  27  * Note: There are no standard multisample positions defined in OpenGL
  28  * specifications. Implementations have the freedom to pick the positions
  29  * which give plausible results. But the Vulkan specification does define
  30  * standard sample positions. So, we decided to pick the same pattern in
  31  * OpenGL as in Vulkan to keep it uniform across drivers and also to avoid
  32  * breaking applications which rely on this standard pattern.
  33  */
  34
  35 /**
  36  * 1x MSAA has a single sample at the center: (0.5, 0.5) -> (0x8, 0x8).
  37  *
  38  * 2x MSAA sample positions are (0.25, 0.25) and (0.75, 0.75):
  39  *   4 c
  40  * 4 0
  41  * c   1
  42  */
  43 static const uint32_t
  44 brw_multisample_positions_1x_2x = 0x0088cc44;
  45
  46 /**
  47  * Sample positions:
  48  *   2 6 a e
  49  * 2   0
  50  * 6       1
  51  * a 2
  52  * e     3
  53  */
  54 static const uint32_t
  55 brw_multisample_positions_4x = 0xae2ae662;
  56
  57 /**
  58  * Sample positions:
  59  *
  60  * From the Ivy Bridge PRM, Vol2 Part1 p304 (3DSTATE_MULTISAMPLE:
  61  * Programming Notes):
  62  *     "When programming the sample offsets (for NUMSAMPLES_4 or _8 and
  63  *     MSRASTMODE_xxx_PATTERN), the order of the samples 0 to 3 (or 7
  64  *     for 8X) must have monotonically increasing distance from the
  65  *     pixel center. This is required to get the correct centroid
  66  *     computation in the device."
  67  *
  68  * Sample positions:
  69  *   1 3 5 7 9 b d f
  70  * 1               7
  71  * 3     3
  72  * 5         0
  73  * 7 5
  74  * 9             2
  75  * b       1
  76  * d   4
  77  * f           6
  78  */
  79 static const uint32_t
  80 brw_multisample_positions_8x[] = { 0x53d97b95, 0xf1bf173d };
  81
  82 /**
  83  * Sample positions:
  84  *
  85  *    0 1 2 3 4 5 6 7 8 9 a b c d e f
  86  * 0   15
  87  * 1                  9
  88  * 2         10
  89  * 3                        7
  90  * 4                               13
  91  * 5                1
  92  * 6        4
  93  * 7                          3
  94  * 8 12
  95  * 9                    0
  96  * a            2
  97  * b                            6
  98  * c     11
  99  * d                      5
 100  * e              8
 101  * f                             14
 102  */
 103 static const uint32_t
 104 brw_multisample_positions_16x[] = {
 105    0xc75a7599, 0xb3dbad36, 0x2c42816e, 0x10eff408
 106 };