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 }