src/gallium/auxiliary/util/u_texture.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2008 VMware, Inc.
   4  * All Rights Reserved.
   5  * Copyright 2008 VMware, Inc.  All rights reserved.
   6  * Copyright 2009 Marek Olšák <maraeo@gmail.com>
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the
  10  * "Software"), to deal in the Software without restriction, including
  11  * without limitation the rights to use, copy, modify, merge, publish,
  12  * distribute, sub license, and/or sell copies of the Software, and to
  13  * permit persons to whom the Software is furnished to do so, subject to
  14  * the following conditions:
  15  *
  16  * The above copyright notice and this permission notice (including the
  17  * next paragraph) shall be included in all copies or substantial portions
  18  * of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  21  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  23  * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
  24  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  25  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  26  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27  *
  28  **************************************************************************/
  29
  30 /**
  31  * @file
  32  * Texture mapping utility functions.
  33  *
  34  * @author Brian Paul
  35  *         Marek Olšák
  36  */
  37
  38 #include "pipe/p_defines.h"
  39
  40 #include "util/u_debug.h"
  41 #include "util/u_texture.h"
  42
  43 void util_map_texcoords2d_onto_cubemap(unsigned face,
  44                                        const float *in_st, unsigned in_stride,
  45                                        float *out_str, unsigned out_stride,
  46                                        boolean allow_scale)
  47 {
  48    int i;
  49    float rx, ry, rz;
  50
  51    /* loop over quad verts */
  52    for (i = 0; i < 4; i++) {
  53       /* Compute sc = +/-scale and tc = +/-scale.
  54        * Not +/-1 to avoid cube face selection ambiguity near the edges,
  55        * though that can still sometimes happen with this scale factor...
  56        *
  57        * XXX: Yep, there is no safe scale factor that will prevent sampling
  58        * the neighbouring face when stretching out.  A more reliable solution
  59        * would be to clamp (sc, tc) against +/- 1.0-1.0/mipsize, in the shader.
  60        *
  61        * Also, this is not necessary when minifying, or 1:1 blits.
  62        */
  63       const float scale = allow_scale ? 0.9999f : 1.0f;
  64       const float sc = (2 * in_st[0] - 1) * scale;
  65       const float tc = (2 * in_st[1] - 1) * scale;
  66
  67       switch (face) {
  68          case PIPE_TEX_FACE_POS_X:
  69             rx = 1;
  70             ry = -tc;
  71             rz = -sc;
  72             break;
  73          case PIPE_TEX_FACE_NEG_X:
  74             rx = -1;
  75             ry = -tc;
  76             rz = sc;
  77             break;
  78          case PIPE_TEX_FACE_POS_Y:
  79             rx = sc;
  80             ry = 1;
  81             rz = tc;
  82             break;
  83          case PIPE_TEX_FACE_NEG_Y:
  84             rx = sc;
  85             ry = -1;
  86             rz = -tc;
  87             break;
  88          case PIPE_TEX_FACE_POS_Z:
  89             rx = sc;
  90             ry = -tc;
  91             rz = 1;
  92             break;
  93          case PIPE_TEX_FACE_NEG_Z:
  94             rx = -sc;
  95             ry = -tc;
  96             rz = -1;
  97             break;
  98          default:
  99             rx = ry = rz = 0;
 100             assert(0);
 101       }
 102
 103       out_str[0] = rx; /*s*/
 104       out_str[1] = ry; /*t*/
 105       out_str[2] = rz; /*r*/
 106
 107       in_st += in_stride;
 108       out_str += out_stride;
 109    }
 110 }