src/gallium/auxiliary/util/u_sampler.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2010 VMware, Inc.
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  21  * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
  22  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  **************************************************************************/
  27
  28
  29 #include "util/format/u_format.h"
  30 #include "u_sampler.h"
  31
  32
  33 /**
  34  * Initialize a pipe_sampler_view.  'view' is considered to have
  35  * uninitialized contents.
  36  */
  37 static void
  38 default_template(struct pipe_sampler_view *view,
  39                  const struct pipe_resource *texture,
  40                  enum pipe_format format,
  41                  unsigned expand_green_blue)
  42 {
  43    memset(view, 0, sizeof(*view));
  44
  45    /* XXX: Check if format is compatible with texture->format.
  46     */
  47
  48    view->target = texture->target;
  49    view->format = format;
  50    view->u.tex.first_level = 0;
  51    view->u.tex.last_level = texture->last_level;
  52    view->u.tex.first_layer = 0;
  53    view->u.tex.last_layer = texture->target == PIPE_TEXTURE_3D ?
  54                                texture->depth0 - 1 : texture->array_size - 1;
  55    view->swizzle_r = PIPE_SWIZZLE_X;
  56    view->swizzle_g = PIPE_SWIZZLE_Y;
  57    view->swizzle_b = PIPE_SWIZZLE_Z;
  58    view->swizzle_a = PIPE_SWIZZLE_W;
  59
  60    /* Override default green and blue component expansion to the requested
  61     * one.
  62     *
  63     * Gallium expands nonexistent components to (0,0,0,1), DX9 expands
  64     * to (1,1,1,1).  Since alpha is always expanded to 1, and red is
  65     * always present, we only really care about green and blue
  66     * components.
  67     *
  68     * To make it look less hackish, one would have to add
  69     * PIPE_SWIZZLE_EXPAND to indicate components for expansion
  70     * and then override without exceptions or favoring one component
  71     * over another.
  72     */
  73    if (format != PIPE_FORMAT_A8_UNORM) {
  74       const struct util_format_description *desc = util_format_description(format);
  75
  76       assert(desc);
  77       if (desc) {
  78          if (desc->swizzle[1] == PIPE_SWIZZLE_0) {
  79             view->swizzle_g = expand_green_blue;
  80          }
  81          if (desc->swizzle[2] == PIPE_SWIZZLE_0) {
  82             view->swizzle_b = expand_green_blue;
  83          }
  84       }
  85    }
  86 }
  87
  88 void
  89 u_sampler_view_default_template(struct pipe_sampler_view *view,
  90                                 const struct pipe_resource *texture,
  91                                 enum pipe_format format)
  92 {
  93    /* Expand to (0, 0, 0, 1) */
  94    default_template(view,
  95                     texture,
  96                     format,
  97                     PIPE_SWIZZLE_0);
  98 }
  99
 100 void
 101 u_sampler_view_default_dx9_template(struct pipe_sampler_view *view,
 102                                     const struct pipe_resource *texture,
 103                                     enum pipe_format format)
 104 {
 105    /* Expand to (1, 1, 1, 1) */
 106    default_template(view,
 107                     texture,
 108                     format,
 109                     PIPE_SWIZZLE_1);
 110 }