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
gen6_get_sample_position(struct gl_context * ctx,struct gl_framebuffer * fb,GLuint index,GLfloat * result)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