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