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    default:
  52       unreachable("Not implemented");
  53    }
  54
  55    /* Convert from U0.4 back to a floating point coordinate. */
  56    result[0] = ((bits >> 4) & 0xf) / 16.0f;
  57    result[1] = (bits & 0xf) / 16.0f;
  58 }
  59
  60 /**
  61  * Sample index layout shows the numbering of slots in a rectangular
  62  * grid of samples with in a pixel. Sample number layout shows the
  63  * rectangular grid of samples roughly corresponding to the real sample
  64  * locations with in a pixel. Sample number layout matches the sample
  65  * index layout in case of 2X and 4x MSAA, but they are different in
  66  * case of 8X MSAA.
  67  *
  68  * 2X MSAA sample index / number layout
  69  *           ---------
  70  *           | 0 | 1 |
  71  *           ---------
  72  *
  73  * 4X MSAA sample index / number layout
  74  *           ---------
  75  *           | 0 | 1 |
  76  *           ---------
  77  *           | 2 | 3 |
  78  *           ---------
  79  *
  80  * 8X MSAA sample index layout    8x MSAA sample number layout
  81  *           ---------                      ---------
  82  *           | 0 | 1 |                      | 5 | 2 |
  83  *           ---------                      ---------
  84  *           | 2 | 3 |                      | 4 | 6 |
  85  *           ---------                      ---------
  86  *           | 4 | 5 |                      | 0 | 3 |
  87  *           ---------                      ---------
  88  *           | 6 | 7 |                      | 7 | 1 |
  89  *           ---------                      ---------
  90  *
  91  * A sample map is used to map sample indices to sample numbers.
  92  */
  93 void
  94 gen6_set_sample_maps(struct gl_context *ctx)
  95 {
  96    uint8_t map_2x[2] = {0, 1};
  97    uint8_t map_4x[4] = {0, 1, 2, 3};
  98    uint8_t map_8x[8] = {5, 2, 4, 6, 0, 3, 7, 1};
  99
 100    memcpy(ctx->Const.SampleMap2x, map_2x, sizeof(map_2x));
 101    memcpy(ctx->Const.SampleMap4x, map_4x, sizeof(map_4x));
 102    memcpy(ctx->Const.SampleMap8x, map_8x, sizeof(map_8x));
 103 }
 104
 105 /**
 106  * 3DSTATE_MULTISAMPLE
 107  */
 108 void
 109 gen6_emit_3dstate_multisample(struct brw_context *brw,
 110                               unsigned num_samples)
 111 {
 112    uint32_t number_of_multisamples = 0;
 113    uint32_t sample_positions_3210 = 0;
 114    uint32_t sample_positions_7654 = 0;
 115
 116    assert(brw->gen < 8);
 117
 118    switch (num_samples) {
 119    case 0:
 120    case 1:
 121       number_of_multisamples = MS_NUMSAMPLES_1;
 122       break;
 123    case 4:
 124       number_of_multisamples = MS_NUMSAMPLES_4;
 125       sample_positions_3210 = brw_multisample_positions_4x;
 126       break;
 127    case 8:
 128       number_of_multisamples = MS_NUMSAMPLES_8;
 129       sample_positions_3210 = brw_multisample_positions_8x[0];
 130       sample_positions_7654 = brw_multisample_positions_8x[1];
 131       break;
 132    default:
 133       unreachable("Unrecognized num_samples in gen6_emit_3dstate_multisample");
 134    }
 135
 136    int len = brw->gen >= 7 ? 4 : 3;
 137    BEGIN_BATCH(len);
 138    OUT_BATCH(_3DSTATE_MULTISAMPLE << 16 | (len - 2));
 139    OUT_BATCH(MS_PIXEL_LOCATION_CENTER | number_of_multisamples);
 140    OUT_BATCH(sample_positions_3210);
 141    if (brw->gen >= 7)
 142       OUT_BATCH(sample_positions_7654);
 143    ADVANCE_BATCH();
 144 }
 145
 146 unsigned
 147 gen6_determine_sample_mask(struct brw_context *brw)
 148 {
 149    struct gl_context *ctx = &brw->ctx;
 150    float coverage = 1.0f;
 151    float coverage_invert = false;
 152    unsigned sample_mask = ~0u;
 153
 154    /* BRW_NEW_NUM_SAMPLES */
 155    unsigned num_samples = brw->num_samples;
 156
 157    if (ctx->Multisample._Enabled) {
 158       if (ctx->Multisample.SampleCoverage) {
 159          coverage = ctx->Multisample.SampleCoverageValue;
 160          coverage_invert = ctx->Multisample.SampleCoverageInvert;
 161       }
 162       if (ctx->Multisample.SampleMask) {
 163          sample_mask = ctx->Multisample.SampleMaskValue;
 164       }
 165    }
 166
 167    if (num_samples > 1) {
 168       int coverage_int = (int) (num_samples * coverage + 0.5f);
 169       uint32_t coverage_bits = (1 << coverage_int) - 1;
 170       if (coverage_invert)
 171          coverage_bits ^= (1 << num_samples) - 1;
 172       return coverage_bits & sample_mask;
 173    } else {
 174       return 1;
 175    }
 176 }
 177
 178 /**
 179  * 3DSTATE_SAMPLE_MASK
 180  */
 181 void
 182 gen6_emit_3dstate_sample_mask(struct brw_context *brw, unsigned mask)
 183 {
 184    BEGIN_BATCH(2);
 185    OUT_BATCH(_3DSTATE_SAMPLE_MASK << 16 | (2 - 2));
 186    OUT_BATCH(mask);
 187    ADVANCE_BATCH();
 188 }
 189
 190 static void
 191 upload_multisample_state(struct brw_context *brw)
 192 {
 193    /* BRW_NEW_NUM_SAMPLES */
 194    gen6_emit_3dstate_multisample(brw, brw->num_samples);
 195    gen6_emit_3dstate_sample_mask(brw, gen6_determine_sample_mask(brw));
 196 }
 197
 198 const struct brw_tracked_state gen6_multisample_state = {
 199    .dirty = {
 200       .mesa = _NEW_MULTISAMPLE,
 201       .brw = BRW_NEW_CONTEXT |
 202              BRW_NEW_NUM_SAMPLES,
 203    },
 204    .emit = upload_multisample_state
 205 };