src/mesa/drivers/dri/i965/gen6_multisample_state.c

   1 /*
   2  * Copyright © 2012 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 "intel_batchbuffer.h"
  25
  26 #include "brw_context.h"
  27 #include "brw_defines.h"
  28 #include "brw_multisample_state.h"
  29 #include "main/framebuffer.h"
  30
  31 void
  32 gen6_get_sample_position(struct gl_context *ctx,
  33                          struct gl_framebuffer *fb,
  34                          GLuint index, GLfloat *result)
  35 {
  36    uint8_t bits;
  37
  38    switch (_mesa_geometric_samples(fb)) {
  39    case 1:
  40       result[0] = result[1] = 0.5f;
  41       return;
  42    case 2:
  43       bits = brw_multisample_positions_1x_2x >> (8 * index);
  44       break;
  45    case 4:
  46       bits = brw_multisample_positions_4x >> (8 * index);
  47       break;
  48    case 8:
  49       bits = brw_multisample_positions_8x[index >> 2] >> (8 * (index & 3));
  50       break;
  51    case 16:
  52       bits = brw_multisample_positions_16x[index >> 2] >> (8 * (index & 3));
  53       break;
  54    default:
  55       unreachable("Not implemented");
  56    }
  57
  58    /* Convert from U0.4 back to a floating point coordinate. */
  59    result[0] = ((bits >> 4) & 0xf) / 16.0f;
  60    result[1] = (bits & 0xf) / 16.0f;
  61 }
  62
  63 /**
  64  * Sample index layout shows the numbering of slots in a rectangular
  65  * grid of samples with in a pixel. Sample number layout shows the
  66  * rectangular grid of samples roughly corresponding to the real sample
  67  * locations with in a pixel. Sample number layout matches the sample
  68  * index layout in case of 2X and 4x MSAA, but they are different in
  69  * case of 8X MSAA.
  70  *
  71  * 2X MSAA sample index / number layout
  72  *           ---------
  73  *           | 0 | 1 |
  74  *           ---------
  75  *
  76  * 4X MSAA sample index / number layout
  77  *           ---------
  78  *           | 0 | 1 |
  79  *           ---------
  80  *           | 2 | 3 |
  81  *           ---------
  82  *
  83  * 8X MSAA sample index layout    8x MSAA sample number layout
  84  *           ---------                      ---------
  85  *           | 0 | 1 |                      | 5 | 2 |
  86  *           ---------                      ---------
  87  *           | 2 | 3 |                      | 4 | 6 |
  88  *           ---------                      ---------
  89  *           | 4 | 5 |                      | 0 | 3 |
  90  *           ---------                      ---------
  91  *           | 6 | 7 |                      | 7 | 1 |
  92  *           ---------                      ---------
  93  *
  94  * 16X MSAA sample index layout  16x MSAA sample number layout
  95  *         -----------------            -----------------
  96  *         | 0 | 1 | 2 | 3 |            |15 |10 | 9 | 7 |
  97  *         -----------------            -----------------
  98  *         | 4 | 5 | 6 | 7 |            | 4 | 1 | 3 |13 |
  99  *         -----------------            -----------------
 100  *         | 8 | 9 |10 |11 |            |12 | 2 | 0 | 6 |
 101  *         -----------------            -----------------
 102  *         |12 |13 |14 |15 |            |11 | 8 | 5 |14 |
 103  *         -----------------            -----------------
 104  *
 105  * A sample map is used to map sample indices to sample numbers.
 106  */
 107 void
 108 gen6_set_sample_maps(struct gl_context *ctx)
 109 {
 110    uint8_t map_2x[2] = {0, 1};
 111    uint8_t map_4x[4] = {0, 1, 2, 3};
 112    uint8_t map_8x[8] = {3, 7, 5, 0, 1, 2, 4, 6};
 113    uint8_t map_16x[16] = { 15, 10, 9, 7, 4, 1, 3, 13,
 114                            12, 2, 0, 6, 11, 8, 5, 14 };
 115
 116    memcpy(ctx->Const.SampleMap2x, map_2x, sizeof(map_2x));
 117    memcpy(ctx->Const.SampleMap4x, map_4x, sizeof(map_4x));
 118    memcpy(ctx->Const.SampleMap8x, map_8x, sizeof(map_8x));
 119    memcpy(ctx->Const.SampleMap16x, map_16x, sizeof(map_16x));
 120 }