1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
|
/*
* Mesa 3-D graphics library
* Version: 6.5.3
*
* Copyright (C) 1999-2007 Brian Paul All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* Antialiased Triangle Rasterizer Template
*
* This file is #include'd to generate custom AA triangle rasterizers.
* NOTE: this code hasn't been optimized yet. That'll come after it
* works correctly.
*
* The following macros may be defined to indicate what auxillary information
* must be copmuted across the triangle:
* DO_Z - if defined, compute Z values
* DO_RGBA - if defined, compute RGBA values
* DO_INDEX - if defined, compute color index values
* DO_ATTRIBS - if defined, compute texcoords, varying, etc.
*/
/*void triangle( GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv )*/
{
const SWcontext *swrast = SWRAST_CONTEXT(ctx);
const GLfloat *p0 = v0->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *p1 = v1->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *p2 = v2->attrib[FRAG_ATTRIB_WPOS];
const SWvertex *vMin, *vMid, *vMax;
GLint iyMin, iyMax;
GLfloat yMin, yMax;
GLboolean ltor;
GLfloat majDx, majDy; /* major (i.e. long) edge dx and dy */
SWspan span;
#ifdef DO_Z
GLfloat zPlane[4];
#endif
#ifdef DO_RGBA
GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];
#endif
#ifdef DO_INDEX
GLfloat iPlane[4];
#endif
#if defined(DO_ATTRIBS)
GLfloat attrPlane[FRAG_ATTRIB_MAX][4][4];
GLfloat wPlane[4]; /* win[3] */
#endif
GLfloat bf = SWRAST_CONTEXT(ctx)->_BackfaceSign;
(void) swrast;
INIT_SPAN(span, GL_POLYGON, 0, 0, SPAN_COVERAGE);
/* determine bottom to top order of vertices */
{
GLfloat y0 = v0->attrib[FRAG_ATTRIB_WPOS][1];
GLfloat y1 = v1->attrib[FRAG_ATTRIB_WPOS][1];
GLfloat y2 = v2->attrib[FRAG_ATTRIB_WPOS][1];
if (y0 <= y1) {
if (y1 <= y2) {
vMin = v0; vMid = v1; vMax = v2; /* y0<=y1<=y2 */
}
else if (y2 <= y0) {
vMin = v2; vMid = v0; vMax = v1; /* y2<=y0<=y1 */
}
else {
vMin = v0; vMid = v2; vMax = v1; bf = -bf; /* y0<=y2<=y1 */
}
}
else {
if (y0 <= y2) {
vMin = v1; vMid = v0; vMax = v2; bf = -bf; /* y1<=y0<=y2 */
}
else if (y2 <= y1) {
vMin = v2; vMid = v1; vMax = v0; bf = -bf; /* y2<=y1<=y0 */
}
else {
vMin = v1; vMid = v2; vMax = v0; /* y1<=y2<=y0 */
}
}
}
majDx = vMax->attrib[FRAG_ATTRIB_WPOS][0] - vMin->attrib[FRAG_ATTRIB_WPOS][0];
majDy = vMax->attrib[FRAG_ATTRIB_WPOS][1] - vMin->attrib[FRAG_ATTRIB_WPOS][1];
{
const GLfloat botDx = vMid->attrib[FRAG_ATTRIB_WPOS][0] - vMin->attrib[FRAG_ATTRIB_WPOS][0];
const GLfloat botDy = vMid->attrib[FRAG_ATTRIB_WPOS][1] - vMin->attrib[FRAG_ATTRIB_WPOS][1];
const GLfloat area = majDx * botDy - botDx * majDy;
/* Do backface culling */
if (area * bf < 0 || area == 0 || IS_INF_OR_NAN(area))
return;
ltor = (GLboolean) (area < 0.0F);
}
/* Plane equation setup:
* We evaluate plane equations at window (x,y) coordinates in order
* to compute color, Z, fog, texcoords, etc. This isn't terribly
* efficient but it's easy and reliable.
*/
#ifdef DO_Z
compute_plane(p0, p1, p2, p0[2], p1[2], p2[2], zPlane);
span.arrayMask |= SPAN_Z;
#endif
#ifdef DO_RGBA
if (ctx->Light.ShadeModel == GL_SMOOTH) {
compute_plane(p0, p1, p2, v0->color[RCOMP], v1->color[RCOMP], v2->color[RCOMP], rPlane);
compute_plane(p0, p1, p2, v0->color[GCOMP], v1->color[GCOMP], v2->color[GCOMP], gPlane);
compute_plane(p0, p1, p2, v0->color[BCOMP], v1->color[BCOMP], v2->color[BCOMP], bPlane);
compute_plane(p0, p1, p2, v0->color[ACOMP], v1->color[ACOMP], v2->color[ACOMP], aPlane);
}
else {
constant_plane(v2->color[RCOMP], rPlane);
constant_plane(v2->color[GCOMP], gPlane);
constant_plane(v2->color[BCOMP], bPlane);
constant_plane(v2->color[ACOMP], aPlane);
}
span.arrayMask |= SPAN_RGBA;
#endif
#ifdef DO_INDEX
if (ctx->Light.ShadeModel == GL_SMOOTH) {
compute_plane(p0, p1, p2, (GLfloat) v0->attrib[FRAG_ATTRIB_CI][0],
v1->attrib[FRAG_ATTRIB_CI][0], v2->attrib[FRAG_ATTRIB_CI][0], iPlane);
}
else {
constant_plane(v2->attrib[FRAG_ATTRIB_CI][0], iPlane);
}
span.arrayMask |= SPAN_INDEX;
#endif
#if defined(DO_ATTRIBS)
{
const GLfloat invW0 = v0->attrib[FRAG_ATTRIB_WPOS][3];
const GLfloat invW1 = v1->attrib[FRAG_ATTRIB_WPOS][3];
const GLfloat invW2 = v2->attrib[FRAG_ATTRIB_WPOS][3];
compute_plane(p0, p1, p2, invW0, invW1, invW2, wPlane);
span.attrStepX[FRAG_ATTRIB_WPOS][3] = plane_dx(wPlane);
span.attrStepY[FRAG_ATTRIB_WPOS][3] = plane_dy(wPlane);
ATTRIB_LOOP_BEGIN
GLuint c;
if (swrast->_InterpMode[attr] == GL_FLAT) {
for (c = 0; c < 4; c++) {
constant_plane(v2->attrib[attr][c] * invW2, attrPlane[attr][c]);
}
}
else {
for (c = 0; c < 4; c++) {
const GLfloat a0 = v0->attrib[attr][c] * invW0;
const GLfloat a1 = v1->attrib[attr][c] * invW1;
const GLfloat a2 = v2->attrib[attr][c] * invW2;
compute_plane(p0, p1, p2, a0, a1, a2, attrPlane[attr][c]);
}
}
for (c = 0; c < 4; c++) {
span.attrStepX[attr][c] = plane_dx(attrPlane[attr][c]);
span.attrStepY[attr][c] = plane_dy(attrPlane[attr][c]);
}
ATTRIB_LOOP_END
}
#endif
/* Begin bottom-to-top scan over the triangle.
* The long edge will either be on the left or right side of the
* triangle. We always scan from the long edge toward the shorter
* edges, stopping when we find that coverage = 0. If the long edge
* is on the left we scan left-to-right. Else, we scan right-to-left.
*/
yMin = vMin->attrib[FRAG_ATTRIB_WPOS][1];
yMax = vMax->attrib[FRAG_ATTRIB_WPOS][1];
iyMin = (GLint) yMin;
iyMax = (GLint) yMax + 1;
if (ltor) {
/* scan left to right */
const GLfloat *pMin = vMin->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *pMid = vMid->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *pMax = vMax->attrib[FRAG_ATTRIB_WPOS];
const GLfloat dxdy = majDx / majDy;
const GLfloat xAdj = dxdy < 0.0F ? -dxdy : 0.0F;
GLfloat x = pMin[0] - (yMin - iyMin) * dxdy;
GLint iy;
for (iy = iyMin; iy < iyMax; iy++, x += dxdy) {
GLint ix, startX = (GLint) (x - xAdj);
GLuint count;
GLfloat coverage = 0.0F;
/* skip over fragments with zero coverage */
while (startX < MAX_WIDTH) {
coverage = compute_coveragef(pMin, pMid, pMax, startX, iy);
if (coverage > 0.0F)
break;
startX++;
}
/* enter interior of triangle */
ix = startX;
#if defined(DO_ATTRIBS)
/* compute attributes at left-most fragment */
span.attrStart[FRAG_ATTRIB_WPOS][3] = solve_plane(ix + 0.5, iy + 0.5, wPlane);
ATTRIB_LOOP_BEGIN
GLuint c;
for (c = 0; c < 4; c++) {
span.attrStart[attr][c] = solve_plane(ix + 0.5, iy + 0.5, attrPlane[attr][c]);
}
ATTRIB_LOOP_END
#endif
count = 0;
while (coverage > 0.0F) {
/* (cx,cy) = center of fragment */
const GLfloat cx = ix + 0.5F, cy = iy + 0.5F;
SWspanarrays *array = span.array;
#ifdef DO_INDEX
array->coverage[count] = (GLfloat) compute_coveragei(pMin, pMid, pMax, ix, iy);
#else
array->coverage[count] = coverage;
#endif
#ifdef DO_Z
array->z[count] = (GLuint) solve_plane(cx, cy, zPlane);
#endif
#ifdef DO_RGBA
array->rgba[count][RCOMP] = solve_plane_chan(cx, cy, rPlane);
array->rgba[count][GCOMP] = solve_plane_chan(cx, cy, gPlane);
array->rgba[count][BCOMP] = solve_plane_chan(cx, cy, bPlane);
array->rgba[count][ACOMP] = solve_plane_chan(cx, cy, aPlane);
#endif
#ifdef DO_INDEX
array->index[count] = (GLint) solve_plane(cx, cy, iPlane);
#endif
ix++;
count++;
coverage = compute_coveragef(pMin, pMid, pMax, ix, iy);
}
if (ix <= startX)
continue;
span.x = startX;
span.y = iy;
span.end = (GLuint) ix - (GLuint) startX;
#if defined(DO_RGBA)
_swrast_write_rgba_span(ctx, &span);
#else
_swrast_write_index_span(ctx, &span);
#endif
}
}
else {
/* scan right to left */
const GLfloat *pMin = vMin->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *pMid = vMid->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *pMax = vMax->attrib[FRAG_ATTRIB_WPOS];
const GLfloat dxdy = majDx / majDy;
const GLfloat xAdj = dxdy > 0 ? dxdy : 0.0F;
GLfloat x = pMin[0] - (yMin - iyMin) * dxdy;
GLint iy;
for (iy = iyMin; iy < iyMax; iy++, x += dxdy) {
GLint ix, left, startX = (GLint) (x + xAdj);
GLuint count, n;
GLfloat coverage = 0.0F;
/* make sure we're not past the window edge */
if (startX >= ctx->DrawBuffer->_Xmax) {
startX = ctx->DrawBuffer->_Xmax - 1;
}
/* skip fragments with zero coverage */
while (startX >= 0) {
coverage = compute_coveragef(pMin, pMax, pMid, startX, iy);
if (coverage > 0.0F)
break;
startX--;
}
/* enter interior of triangle */
ix = startX;
count = 0;
while (coverage > 0.0F) {
/* (cx,cy) = center of fragment */
const GLfloat cx = ix + 0.5F, cy = iy + 0.5F;
SWspanarrays *array = span.array;
#ifdef DO_INDEX
array->coverage[ix] = (GLfloat) compute_coveragei(pMin, pMax, pMid, ix, iy);
#else
array->coverage[ix] = coverage;
#endif
#ifdef DO_Z
array->z[ix] = (GLuint) solve_plane(cx, cy, zPlane);
#endif
#ifdef DO_RGBA
array->rgba[ix][RCOMP] = solve_plane_chan(cx, cy, rPlane);
array->rgba[ix][GCOMP] = solve_plane_chan(cx, cy, gPlane);
array->rgba[ix][BCOMP] = solve_plane_chan(cx, cy, bPlane);
array->rgba[ix][ACOMP] = solve_plane_chan(cx, cy, aPlane);
#endif
#ifdef DO_INDEX
array->index[ix] = (GLint) solve_plane(cx, cy, iPlane);
#endif
ix--;
count++;
coverage = compute_coveragef(pMin, pMax, pMid, ix, iy);
}
#if defined(DO_ATTRIBS)
/* compute attributes at left-most fragment */
span.attrStart[FRAG_ATTRIB_WPOS][3] = solve_plane(ix + 1.5, iy + 0.5, wPlane);
ATTRIB_LOOP_BEGIN
GLuint c;
for (c = 0; c < 4; c++) {
span.attrStart[attr][c] = solve_plane(ix + 1.5, iy + 0.5, attrPlane[attr][c]);
}
ATTRIB_LOOP_END
#endif
if (startX <= ix)
continue;
n = (GLuint) startX - (GLuint) ix;
left = ix + 1;
/* shift all values to the left */
/* XXX this is temporary */
{
SWspanarrays *array = span.array;
GLint j;
for (j = 0; j < (GLint) n; j++) {
array->coverage[j] = array->coverage[j + left];
#ifdef DO_RGBA
COPY_CHAN4(array->rgba[j], array->rgba[j + left]);
#endif
#ifdef DO_INDEX
array->index[j] = array->index[j + left];
#endif
#ifdef DO_Z
array->z[j] = array->z[j + left];
#endif
}
}
span.x = left;
span.y = iy;
span.end = n;
#if defined(DO_RGBA)
_swrast_write_rgba_span(ctx, &span);
#else
_swrast_write_index_span(ctx, &span);
#endif
}
}
}
#undef DO_Z
#undef DO_RGBA
#undef DO_INDEX
#undef DO_ATTRIBS
#undef DO_OCCLUSION_TEST
|
