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 "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 */
37static void
38default_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
88void
89u_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
100void
101u_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}
111