1 /**************************************************************************
3 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
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 TUNGSTEN GRAPHICS 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 **************************************************************************/
29 * \brief polygon offset state
31 * \author Keith Whitwell <keith@tungstengraphics.com>
35 #include "util/u_math.h"
36 #include "util/u_memory.h"
37 #include "draw_pipe.h"
42 struct draw_stage stage
;
51 static INLINE
struct offset_stage
*offset_stage( struct draw_stage
*stage
)
53 return (struct offset_stage
*) stage
;
61 * Offset tri Z. Some hardware can handle this, but not usually when
62 * doing unfilled rendering.
64 static void do_offset_tri( struct draw_stage
*stage
,
65 struct prim_header
*header
)
67 const unsigned pos
= draw_current_shader_position_output(stage
->draw
);
68 struct offset_stage
*offset
= offset_stage(stage
);
69 float inv_det
= 1.0f
/ header
->det
;
73 float *v0
= header
->v
[0]->data
[pos
];
74 float *v1
= header
->v
[1]->data
[pos
];
75 float *v2
= header
->v
[2]->data
[pos
];
77 /* edge vectors e = v0 - v2, f = v1 - v2 */
78 float ex
= v0
[0] - v2
[0];
79 float ey
= v0
[1] - v2
[1];
80 float ez
= v0
[2] - v2
[2];
81 float fx
= v1
[0] - v2
[0];
82 float fy
= v1
[1] - v2
[1];
83 float fz
= v1
[2] - v2
[2];
85 /* (a,b) = cross(e,f).xy */
86 float a
= ey
*fz
- ez
*fy
;
87 float b
= ez
*fx
- ex
*fz
;
89 float dzdx
= fabsf(a
* inv_det
);
90 float dzdy
= fabsf(b
* inv_det
);
92 float zoffset
= offset
->units
+ MAX2(dzdx
, dzdy
) * offset
->scale
;
95 zoffset
= (offset
->clamp
< 0.0f
) ? MAX2(zoffset
, offset
->clamp
) :
96 MIN2(zoffset
, offset
->clamp
);
99 * Note: we're applying the offset and clamping per-vertex.
100 * Ideally, the offset is applied per-fragment prior to fragment shading.
102 v0
[2] = CLAMP(v0
[2] + zoffset
, 0.0f
, 1.0f
);
103 v1
[2] = CLAMP(v1
[2] + zoffset
, 0.0f
, 1.0f
);
104 v2
[2] = CLAMP(v2
[2] + zoffset
, 0.0f
, 1.0f
);
106 stage
->next
->tri( stage
->next
, header
);
110 static void offset_tri( struct draw_stage
*stage
,
111 struct prim_header
*header
)
113 struct prim_header tmp
;
115 tmp
.det
= header
->det
;
116 tmp
.flags
= header
->flags
;
117 tmp
.pad
= header
->pad
;
118 tmp
.v
[0] = dup_vert(stage
, header
->v
[0], 0);
119 tmp
.v
[1] = dup_vert(stage
, header
->v
[1], 1);
120 tmp
.v
[2] = dup_vert(stage
, header
->v
[2], 2);
122 do_offset_tri( stage
, &tmp
);
126 static void offset_first_tri( struct draw_stage
*stage
,
127 struct prim_header
*header
)
129 struct offset_stage
*offset
= offset_stage(stage
);
130 const struct pipe_rasterizer_state
*rast
= stage
->draw
->rasterizer
;
131 unsigned fill_mode
= rast
->fill_front
;
134 if (rast
->fill_back
!= rast
->fill_front
) {
135 /* Need to check for back-facing triangle */
136 boolean ccw
= header
->det
< 0.0f
;
137 if (ccw
!= rast
->front_ccw
)
138 fill_mode
= rast
->fill_back
;
141 /* Now determine if we need to do offsetting for the point/line/fill mode */
143 case PIPE_POLYGON_MODE_FILL
:
144 do_offset
= rast
->offset_tri
;
146 case PIPE_POLYGON_MODE_LINE
:
147 do_offset
= rast
->offset_line
;
149 case PIPE_POLYGON_MODE_POINT
:
150 do_offset
= rast
->offset_point
;
153 assert(!"invalid fill_mode in offset_first_tri()");
154 do_offset
= rast
->offset_tri
;
158 offset
->scale
= rast
->offset_scale
;
159 offset
->clamp
= rast
->offset_clamp
;
160 offset
->units
= (float) (rast
->offset_units
* stage
->draw
->mrd
);
163 offset
->scale
= 0.0f
;
164 offset
->clamp
= 0.0f
;
165 offset
->units
= 0.0f
;
169 stage
->tri
= offset_tri
;
170 stage
->tri( stage
, header
);
176 static void offset_flush( struct draw_stage
*stage
,
179 stage
->tri
= offset_first_tri
;
180 stage
->next
->flush( stage
->next
, flags
);
184 static void offset_reset_stipple_counter( struct draw_stage
*stage
)
186 stage
->next
->reset_stipple_counter( stage
->next
);
190 static void offset_destroy( struct draw_stage
*stage
)
192 draw_free_temp_verts( stage
);
198 * Create polygon offset drawing stage.
200 struct draw_stage
*draw_offset_stage( struct draw_context
*draw
)
202 struct offset_stage
*offset
= CALLOC_STRUCT(offset_stage
);
206 offset
->stage
.draw
= draw
;
207 offset
->stage
.name
= "offset";
208 offset
->stage
.next
= NULL
;
209 offset
->stage
.point
= draw_pipe_passthrough_point
;
210 offset
->stage
.line
= draw_pipe_passthrough_line
;
211 offset
->stage
.tri
= offset_first_tri
;
212 offset
->stage
.flush
= offset_flush
;
213 offset
->stage
.reset_stipple_counter
= offset_reset_stipple_counter
;
214 offset
->stage
.destroy
= offset_destroy
;
216 if (!draw_alloc_temp_verts( &offset
->stage
, 3 ))
219 return &offset
->stage
;
223 offset
->stage
.destroy( &offset
->stage
);