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 /**
29 * \brief polygon offset state
30 *
31 * \author Keith Whitwell <keithw@vmware.com>
32 * \author Brian Paul
33 */
34
35 #include "util/format/u_format.h"
36 #include "util/u_math.h"
37 #include "util/u_memory.h"
38 #include "draw_pipe.h"
39
40
41
42 struct offset_stage {
43 struct draw_stage stage;
44
45 float scale;
46 float units;
47 float clamp;
48 };
49
50
51
offset_stage(struct draw_stage * stage)52 static inline struct offset_stage *offset_stage( struct draw_stage *stage )
53 {
54 return (struct offset_stage *) stage;
55 }
56
57
58
59
60
61 /**
62 * Offset tri Z. Some hardware can handle this, but not usually when
63 * doing unfilled rendering.
64 */
do_offset_tri(struct draw_stage * stage,struct prim_header * header)65 static void do_offset_tri( struct draw_stage *stage,
66 struct prim_header *header )
67 {
68 const unsigned pos = draw_current_shader_position_output(stage->draw);
69 struct offset_stage *offset = offset_stage(stage);
70 float inv_det = 1.0f / header->det;
71
72 /* Window coords:
73 */
74 float *v0 = header->v[0]->data[pos];
75 float *v1 = header->v[1]->data[pos];
76 float *v2 = header->v[2]->data[pos];
77
78 /* edge vectors e = v0 - v2, f = v1 - v2 */
79 float ex = v0[0] - v2[0];
80 float ey = v0[1] - v2[1];
81 float ez = v0[2] - v2[2];
82 float fx = v1[0] - v2[0];
83 float fy = v1[1] - v2[1];
84 float fz = v1[2] - v2[2];
85
86 /* (a,b) = cross(e,f).xy */
87 float a = ey*fz - ez*fy;
88 float b = ez*fx - ex*fz;
89
90 float dzdx = fabsf(a * inv_det);
91 float dzdy = fabsf(b * inv_det);
92
93 float zoffset, mult;
94
95 mult = MAX2(dzdx, dzdy) * offset->scale;
96
97 if (stage->draw->floating_point_depth) {
98 float bias;
99 union fi maxz;
100 maxz.f = MAX3(v0[2], v1[2], v2[2]);
101 /* just do the math directly on shifted number */
102 maxz.ui &= 0xff << 23;
103 maxz.i -= 23 << 23;
104 /* Clamping to zero means mrd will be zero for very small numbers,
105 * but specs do not indicate this should be prevented by clamping
106 * mrd to smallest normal number instead. */
107 maxz.i = MAX2(maxz.i, 0);
108
109 bias = offset->units * maxz.f;
110 zoffset = bias + mult;
111 } else {
112 zoffset = offset->units + mult;
113 }
114
115 if (offset->clamp)
116 zoffset = (offset->clamp < 0.0f) ? MAX2(zoffset, offset->clamp) :
117 MIN2(zoffset, offset->clamp);
118
119 /*
120 * Note: we're applying the offset and clamping per-vertex.
121 * Ideally, the offset is applied per-fragment prior to fragment shading.
122 */
123 v0[2] = SATURATE(v0[2] + zoffset);
124 v1[2] = SATURATE(v1[2] + zoffset);
125 v2[2] = SATURATE(v2[2] + zoffset);
126
127 stage->next->tri( stage->next, header );
128 }
129
130
offset_tri(struct draw_stage * stage,struct prim_header * header)131 static void offset_tri( struct draw_stage *stage,
132 struct prim_header *header )
133 {
134 struct prim_header tmp;
135
136 tmp.det = header->det;
137 tmp.flags = header->flags;
138 tmp.pad = header->pad;
139 tmp.v[0] = dup_vert(stage, header->v[0], 0);
140 tmp.v[1] = dup_vert(stage, header->v[1], 1);
141 tmp.v[2] = dup_vert(stage, header->v[2], 2);
142
143 do_offset_tri( stage, &tmp );
144 }
145
146
offset_first_tri(struct draw_stage * stage,struct prim_header * header)147 static void offset_first_tri( struct draw_stage *stage,
148 struct prim_header *header )
149 {
150 struct offset_stage *offset = offset_stage(stage);
151 const struct pipe_rasterizer_state *rast = stage->draw->rasterizer;
152 unsigned fill_mode = rast->fill_front;
153 boolean do_offset;
154
155 if (rast->fill_back != rast->fill_front) {
156 /* Need to check for back-facing triangle */
157 boolean ccw = header->det < 0.0f;
158 if (ccw != rast->front_ccw)
159 fill_mode = rast->fill_back;
160 }
161
162 /* Now determine if we need to do offsetting for the point/line/fill mode */
163 switch (fill_mode) {
164 case PIPE_POLYGON_MODE_FILL:
165 do_offset = rast->offset_tri;
166 break;
167 case PIPE_POLYGON_MODE_LINE:
168 do_offset = rast->offset_line;
169 break;
170 case PIPE_POLYGON_MODE_POINT:
171 do_offset = rast->offset_point;
172 break;
173 default:
174 assert(!"invalid fill_mode in offset_first_tri()");
175 do_offset = rast->offset_tri;
176 }
177
178 if (do_offset) {
179 offset->scale = rast->offset_scale;
180 offset->clamp = rast->offset_clamp;
181
182 /*
183 * If depth is floating point, depth bias is calculated with respect
184 * to the primitive's maximum Z value. Retain the original depth bias
185 * value until that stage.
186 */
187 if (stage->draw->floating_point_depth) {
188 offset->units = (float) rast->offset_units;
189 } else {
190 offset->units = (float) (rast->offset_units * stage->draw->mrd);
191 }
192 }
193 else {
194 offset->scale = 0.0f;
195 offset->clamp = 0.0f;
196 offset->units = 0.0f;
197 }
198
199
200 stage->tri = offset_tri;
201 stage->tri( stage, header );
202 }
203
204
205
206
offset_flush(struct draw_stage * stage,unsigned flags)207 static void offset_flush( struct draw_stage *stage,
208 unsigned flags )
209 {
210 stage->tri = offset_first_tri;
211 stage->next->flush( stage->next, flags );
212 }
213
214
offset_reset_stipple_counter(struct draw_stage * stage)215 static void offset_reset_stipple_counter( struct draw_stage *stage )
216 {
217 stage->next->reset_stipple_counter( stage->next );
218 }
219
220
offset_destroy(struct draw_stage * stage)221 static void offset_destroy( struct draw_stage *stage )
222 {
223 draw_free_temp_verts( stage );
224 FREE( stage );
225 }
226
227
228 /**
229 * Create polygon offset drawing stage.
230 */
draw_offset_stage(struct draw_context * draw)231 struct draw_stage *draw_offset_stage( struct draw_context *draw )
232 {
233 struct offset_stage *offset = CALLOC_STRUCT(offset_stage);
234 if (!offset)
235 goto fail;
236
237 offset->stage.draw = draw;
238 offset->stage.name = "offset";
239 offset->stage.next = NULL;
240 offset->stage.point = draw_pipe_passthrough_point;
241 offset->stage.line = draw_pipe_passthrough_line;
242 offset->stage.tri = offset_first_tri;
243 offset->stage.flush = offset_flush;
244 offset->stage.reset_stipple_counter = offset_reset_stipple_counter;
245 offset->stage.destroy = offset_destroy;
246
247 if (!draw_alloc_temp_verts( &offset->stage, 3 ))
248 goto fail;
249
250 return &offset->stage;
251
252 fail:
253 if (offset)
254 offset->stage.destroy( &offset->stage );
255
256 return NULL;
257 }
258