1 /**************************************************************************
2 *
3 * Copyright 2007 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 /* Authors: Keith Whitwell <[email protected]>
29 */
30
31 #include "util/u_math.h"
32 #include "util/u_memory.h"
33 #include "pipe/p_defines.h"
34 #include "pipe/p_shader_tokens.h"
35 #include "draw_vs.h"
36 #include "draw_pipe.h"
37
38 struct twoside_stage {
39 struct draw_stage stage;
40 float sign; /**< +1 or -1 */
41 int attrib_front0, attrib_back0;
42 int attrib_front1, attrib_back1;
43 };
44
45
46 static inline struct twoside_stage *
twoside_stage(struct draw_stage * stage)47 twoside_stage(struct draw_stage *stage)
48 {
49 return (struct twoside_stage *) stage;
50 }
51
52
53 /**
54 * Copy back color(s) to front color(s).
55 */
56 static inline struct vertex_header *
copy_bfc(struct twoside_stage * twoside,const struct vertex_header * v,unsigned idx)57 copy_bfc(struct twoside_stage *twoside,
58 const struct vertex_header *v,
59 unsigned idx)
60 {
61 struct vertex_header *tmp = dup_vert(&twoside->stage, v, idx);
62
63 if (twoside->attrib_back0 >= 0 && twoside->attrib_front0 >= 0) {
64 COPY_4FV(tmp->data[twoside->attrib_front0],
65 tmp->data[twoside->attrib_back0]);
66 }
67 if (twoside->attrib_back1 >= 0 && twoside->attrib_front1 >= 0) {
68 COPY_4FV(tmp->data[twoside->attrib_front1],
69 tmp->data[twoside->attrib_back1]);
70 }
71
72 return tmp;
73 }
74
75
76 /* Twoside tri:
77 */
78 static void
twoside_tri(struct draw_stage * stage,struct prim_header * header)79 twoside_tri(struct draw_stage *stage,
80 struct prim_header *header)
81 {
82 struct twoside_stage *twoside = twoside_stage(stage);
83
84 if (header->det * twoside->sign < 0.0) {
85 /* this is a back-facing triangle */
86 struct prim_header tmp;
87
88 tmp.det = header->det;
89 tmp.flags = header->flags;
90 tmp.pad = header->pad;
91 /* copy back attribs to front attribs */
92 tmp.v[0] = copy_bfc(twoside, header->v[0], 0);
93 tmp.v[1] = copy_bfc(twoside, header->v[1], 1);
94 tmp.v[2] = copy_bfc(twoside, header->v[2], 2);
95
96 stage->next->tri(stage->next, &tmp);
97 } else {
98 stage->next->tri(stage->next, header);
99 }
100 }
101
102
103 static void
twoside_first_tri(struct draw_stage * stage,struct prim_header * header)104 twoside_first_tri(struct draw_stage *stage,
105 struct prim_header *header)
106 {
107 struct twoside_stage *twoside = twoside_stage(stage);
108 const struct draw_vertex_shader *vs = stage->draw->vs.vertex_shader;
109
110 twoside->attrib_front0 = -1;
111 twoside->attrib_front1 = -1;
112 twoside->attrib_back0 = -1;
113 twoside->attrib_back1 = -1;
114
115 /*
116 * Find which vertex shader outputs are front/back colors
117 * (only first two can be front or back).
118 */
119 for (unsigned i = 0; i < vs->info.num_outputs; i++) {
120 if (vs->info.output_semantic_name[i] == TGSI_SEMANTIC_COLOR) {
121 if (vs->info.output_semantic_index[i] == 0)
122 twoside->attrib_front0 = i;
123 else if (vs->info.output_semantic_index[i] == 1)
124 twoside->attrib_front1 = i;
125 }
126 if (vs->info.output_semantic_name[i] == TGSI_SEMANTIC_BCOLOR) {
127 if (vs->info.output_semantic_index[i] == 0)
128 twoside->attrib_back0 = i;
129 else if (vs->info.output_semantic_index[i] == 1)
130 twoside->attrib_back1 = i;
131 }
132 }
133
134 /*
135 * We'll multiply the primitive's determinant by this sign to determine
136 * if the triangle is back-facing (negative).
137 * sign = -1 for CCW, +1 for CW
138 */
139 twoside->sign = stage->draw->rasterizer->front_ccw ? -1.0f : 1.0f;
140
141 stage->tri = twoside_tri;
142 stage->tri(stage, header);
143 }
144
145
146 static void
twoside_flush(struct draw_stage * stage,unsigned flags)147 twoside_flush(struct draw_stage *stage, unsigned flags)
148 {
149 stage->tri = twoside_first_tri;
150 stage->next->flush(stage->next, flags);
151 }
152
153
154 static void
twoside_reset_stipple_counter(struct draw_stage * stage)155 twoside_reset_stipple_counter(struct draw_stage *stage)
156 {
157 stage->next->reset_stipple_counter(stage->next);
158 }
159
160
161 static void
twoside_destroy(struct draw_stage * stage)162 twoside_destroy(struct draw_stage *stage)
163 {
164 draw_free_temp_verts(stage);
165 FREE(stage);
166 }
167
168
169 /**
170 * Create twoside pipeline stage.
171 */
172 struct draw_stage *
draw_twoside_stage(struct draw_context * draw)173 draw_twoside_stage(struct draw_context *draw)
174 {
175 struct twoside_stage *twoside = CALLOC_STRUCT(twoside_stage);
176 if (!twoside)
177 goto fail;
178
179 twoside->stage.draw = draw;
180 twoside->stage.name = "twoside";
181 twoside->stage.next = NULL;
182 twoside->stage.point = draw_pipe_passthrough_point;
183 twoside->stage.line = draw_pipe_passthrough_line;
184 twoside->stage.tri = twoside_first_tri;
185 twoside->stage.flush = twoside_flush;
186 twoside->stage.reset_stipple_counter = twoside_reset_stipple_counter;
187 twoside->stage.destroy = twoside_destroy;
188
189 if (!draw_alloc_temp_verts(&twoside->stage, 3))
190 goto fail;
191
192 return &twoside->stage;
193
194 fail:
195 if (twoside)
196 twoside->stage.destroy(&twoside->stage);
197
198 return NULL;
199 }
200