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
29
30 /**
31 * 3DSTATE_MULTISAMPLE
32 */
33 void
gen6_emit_3dstate_multisample(struct brw_context * brw,unsigned num_samples)34 gen6_emit_3dstate_multisample(struct brw_context *brw,
35 unsigned num_samples)
36 {
37 struct intel_context *intel = &brw->intel;
38
39 uint32_t number_of_multisamples = 0;
40 uint32_t sample_positions_3210 = 0;
41 uint32_t sample_positions_7654 = 0;
42
43 switch (num_samples) {
44 case 0:
45 case 1:
46 number_of_multisamples = MS_NUMSAMPLES_1;
47 break;
48 case 4:
49 number_of_multisamples = MS_NUMSAMPLES_4;
50 /* Sample positions:
51 * 2 6 a e
52 * 2 0
53 * 6 1
54 * a 2
55 * e 3
56 */
57 sample_positions_3210 = 0xae2ae662;
58 break;
59 case 8:
60 number_of_multisamples = MS_NUMSAMPLES_8;
61 /* Sample positions are based on a solution to the "8 queens" puzzle.
62 * Rationale: in a solution to the 8 queens puzzle, no two queens share
63 * a row, column, or diagonal. This is a desirable property for samples
64 * in a multisampling pattern, because it ensures that the samples are
65 * relatively uniformly distributed through the pixel.
66 *
67 * There are several solutions to the 8 queens puzzle (see
68 * http://en.wikipedia.org/wiki/Eight_queens_puzzle). This solution was
69 * chosen because it has a queen close to the center; this should
70 * improve the accuracy of centroid interpolation, since the hardware
71 * implements centroid interpolation by choosing the centermost sample
72 * that overlaps with the primitive being drawn.
73 *
74 * Note: from the Ivy Bridge PRM, Vol2 Part1 p304 (3DSTATE_MULTISAMPLE:
75 * Programming Notes):
76 *
77 * "When programming the sample offsets (for NUMSAMPLES_4 or _8 and
78 * MSRASTMODE_xxx_PATTERN), the order of the samples 0 to 3 (or 7
79 * for 8X) must have monotonically increasing distance from the
80 * pixel center. This is required to get the correct centroid
81 * computation in the device."
82 *
83 * Sample positions:
84 * 1 3 5 7 9 b d f
85 * 1 5
86 * 3 2
87 * 5 6
88 * 7 4
89 * 9 0
90 * b 3
91 * d 1
92 * f 7
93 */
94 sample_positions_3210 = 0xdbb39d79;
95 sample_positions_7654 = 0x3ff55117;
96 break;
97 default:
98 assert(!"Unrecognized num_samples in gen6_emit_3dstate_multisample");
99 break;
100 }
101
102 int len = intel->gen >= 7 ? 4 : 3;
103 BEGIN_BATCH(len);
104 OUT_BATCH(_3DSTATE_MULTISAMPLE << 16 | (len - 2));
105 OUT_BATCH(MS_PIXEL_LOCATION_CENTER | number_of_multisamples);
106 OUT_BATCH(sample_positions_3210);
107 if (intel->gen >= 7)
108 OUT_BATCH(sample_positions_7654);
109 ADVANCE_BATCH();
110 }
111
112
113 /**
114 * 3DSTATE_SAMPLE_MASK
115 */
116 void
gen6_emit_3dstate_sample_mask(struct brw_context * brw,unsigned num_samples,float coverage,bool coverage_invert)117 gen6_emit_3dstate_sample_mask(struct brw_context *brw,
118 unsigned num_samples, float coverage,
119 bool coverage_invert)
120 {
121 struct intel_context *intel = &brw->intel;
122
123 BEGIN_BATCH(2);
124 OUT_BATCH(_3DSTATE_SAMPLE_MASK << 16 | (2 - 2));
125 if (num_samples > 1) {
126 int coverage_int = (int) (num_samples * coverage + 0.5);
127 uint32_t coverage_bits = (1 << coverage_int) - 1;
128 if (coverage_invert)
129 coverage_bits ^= (1 << num_samples) - 1;
130 OUT_BATCH(coverage_bits);
131 } else {
132 OUT_BATCH(1);
133 }
134 ADVANCE_BATCH();
135 }
136
137
upload_multisample_state(struct brw_context * brw)138 static void upload_multisample_state(struct brw_context *brw)
139 {
140 struct intel_context *intel = &brw->intel;
141 struct gl_context *ctx = &intel->ctx;
142 float coverage = 1.0;
143 float coverage_invert = false;
144
145 /* _NEW_BUFFERS */
146 unsigned num_samples = ctx->DrawBuffer->Visual.samples;
147
148 /* _NEW_MULTISAMPLE */
149 if (ctx->Multisample._Enabled && ctx->Multisample.SampleCoverage) {
150 coverage = ctx->Multisample.SampleCoverageValue;
151 coverage_invert = ctx->Multisample.SampleCoverageInvert;
152 }
153
154 /* 3DSTATE_MULTISAMPLE is nonpipelined. */
155 intel_emit_post_sync_nonzero_flush(intel);
156
157 gen6_emit_3dstate_multisample(brw, num_samples);
158 gen6_emit_3dstate_sample_mask(brw, num_samples, coverage, coverage_invert);
159 }
160
161
162 const struct brw_tracked_state gen6_multisample_state = {
163 .dirty = {
164 .mesa = _NEW_BUFFERS |
165 _NEW_MULTISAMPLE,
166 .brw = BRW_NEW_CONTEXT,
167 .cache = 0
168 },
169 .emit = upload_multisample_state
170 };
171