1 /**************************************************************************
3 * Copyright 2007 VMware, Inc.
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:
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
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.
26 **************************************************************************/
28 /* Authors: Keith Whitwell <keithw@vmware.com>
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"
36 #include "draw_pipe.h"
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
;
46 static inline struct twoside_stage
*twoside_stage( struct draw_stage
*stage
)
48 return (struct twoside_stage
*)stage
;
52 * Copy back color(s) to front color(s).
54 static inline struct vertex_header
*
55 copy_bfc( struct twoside_stage
*twoside
,
56 const struct vertex_header
*v
,
59 struct vertex_header
*tmp
= dup_vert( &twoside
->stage
, v
, idx
);
61 if (twoside
->attrib_back0
>= 0 && twoside
->attrib_front0
>= 0) {
62 COPY_4FV(tmp
->data
[twoside
->attrib_front0
],
63 tmp
->data
[twoside
->attrib_back0
]);
65 if (twoside
->attrib_back1
>= 0 && twoside
->attrib_front1
>= 0) {
66 COPY_4FV(tmp
->data
[twoside
->attrib_front1
],
67 tmp
->data
[twoside
->attrib_back1
]);
76 static void twoside_tri( struct draw_stage
*stage
,
77 struct prim_header
*header
)
79 struct twoside_stage
*twoside
= twoside_stage(stage
);
81 if (header
->det
* twoside
->sign
< 0.0) {
82 /* this is a back-facing triangle */
83 struct prim_header tmp
;
85 tmp
.det
= header
->det
;
86 tmp
.flags
= header
->flags
;
87 tmp
.pad
= header
->pad
;
88 /* copy back attribs to front attribs */
89 tmp
.v
[0] = copy_bfc(twoside
, header
->v
[0], 0);
90 tmp
.v
[1] = copy_bfc(twoside
, header
->v
[1], 1);
91 tmp
.v
[2] = copy_bfc(twoside
, header
->v
[2], 2);
93 stage
->next
->tri( stage
->next
, &tmp
);
96 stage
->next
->tri( stage
->next
, header
);
102 static void twoside_first_tri( struct draw_stage
*stage
,
103 struct prim_header
*header
)
105 struct twoside_stage
*twoside
= twoside_stage(stage
);
106 const struct draw_vertex_shader
*vs
= stage
->draw
->vs
.vertex_shader
;
109 twoside
->attrib_front0
= -1;
110 twoside
->attrib_front1
= -1;
111 twoside
->attrib_back0
= -1;
112 twoside
->attrib_back1
= -1;
114 /* Find which vertex shader outputs are front/back colors */
115 for (i
= 0; i
< vs
->info
.num_outputs
; i
++) {
116 if (vs
->info
.output_semantic_name
[i
] == TGSI_SEMANTIC_COLOR
) {
117 if (vs
->info
.output_semantic_index
[i
] == 0)
118 twoside
->attrib_front0
= i
;
120 twoside
->attrib_front1
= i
;
122 if (vs
->info
.output_semantic_name
[i
] == TGSI_SEMANTIC_BCOLOR
) {
123 if (vs
->info
.output_semantic_index
[i
] == 0)
124 twoside
->attrib_back0
= i
;
126 twoside
->attrib_back1
= i
;
131 * We'll multiply the primitive's determinant by this sign to determine
132 * if the triangle is back-facing (negative).
133 * sign = -1 for CCW, +1 for CW
135 twoside
->sign
= stage
->draw
->rasterizer
->front_ccw
? -1.0f
: 1.0f
;
137 stage
->tri
= twoside_tri
;
138 stage
->tri( stage
, header
);
142 static void twoside_flush( struct draw_stage
*stage
, unsigned flags
)
144 stage
->tri
= twoside_first_tri
;
145 stage
->next
->flush( stage
->next
, flags
);
149 static void twoside_reset_stipple_counter( struct draw_stage
*stage
)
151 stage
->next
->reset_stipple_counter( stage
->next
);
155 static void twoside_destroy( struct draw_stage
*stage
)
157 draw_free_temp_verts( stage
);
163 * Create twoside pipeline stage.
165 struct draw_stage
*draw_twoside_stage( struct draw_context
*draw
)
167 struct twoside_stage
*twoside
= CALLOC_STRUCT(twoside_stage
);
171 twoside
->stage
.draw
= draw
;
172 twoside
->stage
.name
= "twoside";
173 twoside
->stage
.next
= NULL
;
174 twoside
->stage
.point
= draw_pipe_passthrough_point
;
175 twoside
->stage
.line
= draw_pipe_passthrough_line
;
176 twoside
->stage
.tri
= twoside_first_tri
;
177 twoside
->stage
.flush
= twoside_flush
;
178 twoside
->stage
.reset_stipple_counter
= twoside_reset_stipple_counter
;
179 twoside
->stage
.destroy
= twoside_destroy
;
181 if (!draw_alloc_temp_verts( &twoside
->stage
, 3 ))
184 return &twoside
->stage
;
188 twoside
->stage
.destroy( &twoside
->stage
);