2 * Mesa 3-D graphics library
5 * Copyright (C) 1999-2007 Brian Paul All Rights Reserved.
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:
14 * The above copyright notice and this permission notice shall be included
15 * in all copies or substantial portions of the Software.
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.
27 * Antialiased Triangle Rasterizer Template
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
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_ATTRIBS - if defined, compute texcoords, varying, etc.
39 /*void triangle( struct gl_context *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv )*/
41 const SWcontext *swrast = SWRAST_CONTEXT(ctx);
42 const GLfloat *p0 = v0->attrib[FRAG_ATTRIB_WPOS];
43 const GLfloat *p1 = v1->attrib[FRAG_ATTRIB_WPOS];
44 const GLfloat *p2 = v2->attrib[FRAG_ATTRIB_WPOS];
45 const SWvertex *vMin, *vMid, *vMax;
49 GLfloat majDx, majDy; /* major (i.e. long) edge dx and dy */
56 GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];
57 #if defined(DO_ATTRIBS)
58 GLfloat attrPlane[FRAG_ATTRIB_MAX][4][4];
59 GLfloat wPlane[4]; /* win[3] */
61 GLfloat bf = SWRAST_CONTEXT(ctx)->_BackfaceCullSign;
65 INIT_SPAN(span, GL_POLYGON);
66 span.arrayMask = SPAN_COVERAGE;
68 /* determine bottom to top order of vertices */
70 GLfloat y0 = v0->attrib[FRAG_ATTRIB_WPOS][1];
71 GLfloat y1 = v1->attrib[FRAG_ATTRIB_WPOS][1];
72 GLfloat y2 = v2->attrib[FRAG_ATTRIB_WPOS][1];
75 vMin = v0; vMid = v1; vMax = v2; /* y0<=y1<=y2 */
78 vMin = v2; vMid = v0; vMax = v1; /* y2<=y0<=y1 */
81 vMin = v0; vMid = v2; vMax = v1; bf = -bf; /* y0<=y2<=y1 */
86 vMin = v1; vMid = v0; vMax = v2; bf = -bf; /* y1<=y0<=y2 */
89 vMin = v2; vMid = v1; vMax = v0; bf = -bf; /* y2<=y1<=y0 */
92 vMin = v1; vMid = v2; vMax = v0; /* y1<=y2<=y0 */
97 majDx = vMax->attrib[FRAG_ATTRIB_WPOS][0] - vMin->attrib[FRAG_ATTRIB_WPOS][0];
98 majDy = vMax->attrib[FRAG_ATTRIB_WPOS][1] - vMin->attrib[FRAG_ATTRIB_WPOS][1];
100 /* front/back-face determination and cullling */
102 const GLfloat botDx = vMid->attrib[FRAG_ATTRIB_WPOS][0] - vMin->attrib[FRAG_ATTRIB_WPOS][0];
103 const GLfloat botDy = vMid->attrib[FRAG_ATTRIB_WPOS][1] - vMin->attrib[FRAG_ATTRIB_WPOS][1];
104 const GLfloat area = majDx * botDy - botDx * majDy;
105 /* Do backface culling */
106 if (area * bf < 0 || area == 0 || IS_INF_OR_NAN(area))
108 ltor = (GLboolean) (area < 0.0F);
110 span.facing = area * swrast->_BackfaceSign > 0.0F;
113 /* Plane equation setup:
114 * We evaluate plane equations at window (x,y) coordinates in order
115 * to compute color, Z, fog, texcoords, etc. This isn't terribly
116 * efficient but it's easy and reliable.
119 compute_plane(p0, p1, p2, p0[2], p1[2], p2[2], zPlane);
120 span.arrayMask |= SPAN_Z;
122 if (ctx->Light.ShadeModel == GL_SMOOTH) {
123 compute_plane(p0, p1, p2, v0->color[RCOMP], v1->color[RCOMP], v2->color[RCOMP], rPlane);
124 compute_plane(p0, p1, p2, v0->color[GCOMP], v1->color[GCOMP], v2->color[GCOMP], gPlane);
125 compute_plane(p0, p1, p2, v0->color[BCOMP], v1->color[BCOMP], v2->color[BCOMP], bPlane);
126 compute_plane(p0, p1, p2, v0->color[ACOMP], v1->color[ACOMP], v2->color[ACOMP], aPlane);
129 constant_plane(v2->color[RCOMP], rPlane);
130 constant_plane(v2->color[GCOMP], gPlane);
131 constant_plane(v2->color[BCOMP], bPlane);
132 constant_plane(v2->color[ACOMP], aPlane);
134 span.arrayMask |= SPAN_RGBA;
135 #if defined(DO_ATTRIBS)
137 const GLfloat invW0 = v0->attrib[FRAG_ATTRIB_WPOS][3];
138 const GLfloat invW1 = v1->attrib[FRAG_ATTRIB_WPOS][3];
139 const GLfloat invW2 = v2->attrib[FRAG_ATTRIB_WPOS][3];
140 compute_plane(p0, p1, p2, invW0, invW1, invW2, wPlane);
141 span.attrStepX[FRAG_ATTRIB_WPOS][3] = plane_dx(wPlane);
142 span.attrStepY[FRAG_ATTRIB_WPOS][3] = plane_dy(wPlane);
145 if (swrast->_InterpMode[attr] == GL_FLAT) {
146 for (c = 0; c < 4; c++) {
147 constant_plane(v2->attrib[attr][c] * invW2, attrPlane[attr][c]);
151 for (c = 0; c < 4; c++) {
152 const GLfloat a0 = v0->attrib[attr][c] * invW0;
153 const GLfloat a1 = v1->attrib[attr][c] * invW1;
154 const GLfloat a2 = v2->attrib[attr][c] * invW2;
155 compute_plane(p0, p1, p2, a0, a1, a2, attrPlane[attr][c]);
158 for (c = 0; c < 4; c++) {
159 span.attrStepX[attr][c] = plane_dx(attrPlane[attr][c]);
160 span.attrStepY[attr][c] = plane_dy(attrPlane[attr][c]);
166 /* Begin bottom-to-top scan over the triangle.
167 * The long edge will either be on the left or right side of the
168 * triangle. We always scan from the long edge toward the shorter
169 * edges, stopping when we find that coverage = 0. If the long edge
170 * is on the left we scan left-to-right. Else, we scan right-to-left.
172 yMin = vMin->attrib[FRAG_ATTRIB_WPOS][1];
173 yMax = vMax->attrib[FRAG_ATTRIB_WPOS][1];
174 iyMin = (GLint) yMin;
175 iyMax = (GLint) yMax + 1;
178 /* scan left to right */
179 const GLfloat *pMin = vMin->attrib[FRAG_ATTRIB_WPOS];
180 const GLfloat *pMid = vMid->attrib[FRAG_ATTRIB_WPOS];
181 const GLfloat *pMax = vMax->attrib[FRAG_ATTRIB_WPOS];
182 const GLfloat dxdy = majDx / majDy;
183 const GLfloat xAdj = dxdy < 0.0F ? -dxdy : 0.0F;
186 #pragma omp parallel for schedule(dynamic) private(iy) firstprivate(span)
188 for (iy = iyMin; iy < iyMax; iy++) {
189 GLfloat x = pMin[0] - (yMin - iy) * dxdy;
190 GLint ix, startX = (GLint) (x - xAdj);
192 GLfloat coverage = 0.0F;
195 /* each thread needs to use a different (global) SpanArrays variable */
196 span.array = SWRAST_CONTEXT(ctx)->SpanArrays + omp_get_thread_num();
198 /* skip over fragments with zero coverage */
199 while (startX < MAX_WIDTH) {
200 coverage = compute_coveragef(pMin, pMid, pMax, startX, iy);
206 /* enter interior of triangle */
209 #if defined(DO_ATTRIBS)
210 /* compute attributes at left-most fragment */
211 span.attrStart[FRAG_ATTRIB_WPOS][3] = solve_plane(ix + 0.5F, iy + 0.5F, wPlane);
214 for (c = 0; c < 4; c++) {
215 span.attrStart[attr][c] = solve_plane(ix + 0.5F, iy + 0.5F, attrPlane[attr][c]);
221 while (coverage > 0.0F) {
222 /* (cx,cy) = center of fragment */
223 const GLfloat cx = ix + 0.5F, cy = iy + 0.5F;
224 SWspanarrays *array = span.array;
225 array->coverage[count] = coverage;
227 array->z[count] = (GLuint) solve_plane(cx, cy, zPlane);
229 array->rgba[count][RCOMP] = solve_plane_chan(cx, cy, rPlane);
230 array->rgba[count][GCOMP] = solve_plane_chan(cx, cy, gPlane);
231 array->rgba[count][BCOMP] = solve_plane_chan(cx, cy, bPlane);
232 array->rgba[count][ACOMP] = solve_plane_chan(cx, cy, aPlane);
235 coverage = compute_coveragef(pMin, pMid, pMax, ix, iy);
241 span.end = (GLuint) ix - (GLuint) startX;
242 _swrast_write_rgba_span(ctx, &span);
247 /* scan right to left */
248 const GLfloat *pMin = vMin->attrib[FRAG_ATTRIB_WPOS];
249 const GLfloat *pMid = vMid->attrib[FRAG_ATTRIB_WPOS];
250 const GLfloat *pMax = vMax->attrib[FRAG_ATTRIB_WPOS];
251 const GLfloat dxdy = majDx / majDy;
252 const GLfloat xAdj = dxdy > 0 ? dxdy : 0.0F;
255 #pragma omp parallel for schedule(dynamic) private(iy) firstprivate(span)
257 for (iy = iyMin; iy < iyMax; iy++) {
258 GLfloat x = pMin[0] - (yMin - iy) * dxdy;
259 GLint ix, left, startX = (GLint) (x + xAdj);
261 GLfloat coverage = 0.0F;
264 /* each thread needs to use a different (global) SpanArrays variable */
265 span.array = SWRAST_CONTEXT(ctx)->SpanArrays + omp_get_thread_num();
267 /* make sure we're not past the window edge */
268 if (startX >= ctx->DrawBuffer->_Xmax) {
269 startX = ctx->DrawBuffer->_Xmax - 1;
272 /* skip fragments with zero coverage */
274 coverage = compute_coveragef(pMin, pMax, pMid, startX, iy);
280 /* enter interior of triangle */
283 while (coverage > 0.0F) {
284 /* (cx,cy) = center of fragment */
285 const GLfloat cx = ix + 0.5F, cy = iy + 0.5F;
286 SWspanarrays *array = span.array;
288 array->coverage[ix] = coverage;
290 array->z[ix] = (GLuint) solve_plane(cx, cy, zPlane);
292 array->rgba[ix][RCOMP] = solve_plane_chan(cx, cy, rPlane);
293 array->rgba[ix][GCOMP] = solve_plane_chan(cx, cy, gPlane);
294 array->rgba[ix][BCOMP] = solve_plane_chan(cx, cy, bPlane);
295 array->rgba[ix][ACOMP] = solve_plane_chan(cx, cy, aPlane);
298 coverage = compute_coveragef(pMin, pMax, pMid, ix, iy);
301 #if defined(DO_ATTRIBS)
302 /* compute attributes at left-most fragment */
303 span.attrStart[FRAG_ATTRIB_WPOS][3] = solve_plane(ix + 1.5F, iy + 0.5F, wPlane);
306 for (c = 0; c < 4; c++) {
307 span.attrStart[attr][c] = solve_plane(ix + 1.5F, iy + 0.5F, attrPlane[attr][c]);
313 n = (GLuint) startX - (GLuint) ix;
317 /* shift all values to the left */
318 /* XXX this is temporary */
320 SWspanarrays *array = span.array;
322 for (j = 0; j < (GLint) n; j++) {
323 array->coverage[j] = array->coverage[j + left];
324 COPY_CHAN4(array->rgba[j], array->rgba[j + left]);
326 array->z[j] = array->z[j + left];
334 _swrast_write_rgba_span(ctx, &span);
343 #undef DO_OCCLUSION_TEST