s_aatriangle.c revision 10f30eb43835c57c00783390a02d72daf4f78e26
1/* $Id: s_aatriangle.c,v 1.21 2001/12/17 04:54:35 brianp Exp $ */ 2 3/* 4 * Mesa 3-D graphics library 5 * Version: 4.0.1 6 * 7 * Copyright (C) 1999-2001 Brian Paul All Rights Reserved. 8 * 9 * Permission is hereby granted, free of charge, to any person obtaining a 10 * copy of this software and associated documentation files (the "Software"), 11 * to deal in the Software without restriction, including without limitation 12 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 13 * and/or sell copies of the Software, and to permit persons to whom the 14 * Software is furnished to do so, subject to the following conditions: 15 * 16 * The above copyright notice and this permission notice shall be included 17 * in all copies or substantial portions of the Software. 18 * 19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 20 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 22 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN 23 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 24 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 25 */ 26 27 28/* 29 * Antialiased Triangle rasterizers 30 */ 31 32 33#include "mem.h" 34#include "mmath.h" 35#include "s_aatriangle.h" 36#include "s_context.h" 37#include "s_span.h" 38 39 40/* 41 * Compute coefficients of a plane using the X,Y coords of the v0, v1, v2 42 * vertices and the given Z values. 43 * A point (x,y,z) lies on plane iff a*x+b*y+c*z+d = 0. 44 */ 45static INLINE void 46compute_plane(const GLfloat v0[], const GLfloat v1[], const GLfloat v2[], 47 GLfloat z0, GLfloat z1, GLfloat z2, GLfloat plane[4]) 48{ 49 const GLfloat px = v1[0] - v0[0]; 50 const GLfloat py = v1[1] - v0[1]; 51 const GLfloat pz = z1 - z0; 52 53 const GLfloat qx = v2[0] - v0[0]; 54 const GLfloat qy = v2[1] - v0[1]; 55 const GLfloat qz = z2 - z0; 56 57 /* Crossproduct "(a,b,c):= dv1 x dv2" is orthogonal to plane. */ 58 const GLfloat a = py * qz - pz * qy; 59 const GLfloat b = pz * qx - px * qz; 60 const GLfloat c = px * qy - py * qx; 61 /* Point on the plane = "r*(a,b,c) + w", with fixed "r" depending 62 on the distance of plane from origin and arbitrary "w" parallel 63 to the plane. */ 64 /* The scalar product "(r*(a,b,c)+w)*(a,b,c)" is "r*(a^2+b^2+c^2)", 65 which is equal to "-d" below. */ 66 const GLfloat d = -(a * v0[0] + b * v0[1] + c * z0); 67 68 plane[0] = a; 69 plane[1] = b; 70 plane[2] = c; 71 plane[3] = d; 72} 73 74 75/* 76 * Compute coefficients of a plane with a constant Z value. 77 */ 78static INLINE void 79constant_plane(GLfloat value, GLfloat plane[4]) 80{ 81 plane[0] = 0.0; 82 plane[1] = 0.0; 83 plane[2] = -1.0; 84 plane[3] = value; 85} 86 87#define CONSTANT_PLANE(VALUE, PLANE) \ 88do { \ 89 PLANE[0] = 0.0F; \ 90 PLANE[1] = 0.0F; \ 91 PLANE[2] = -1.0F; \ 92 PLANE[3] = VALUE; \ 93} while (0) 94 95 96 97/* 98 * Solve plane equation for Z at (X,Y). 99 */ 100static INLINE GLfloat 101solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4]) 102{ 103 ASSERT(plane[2] != 0.0F); 104 return (plane[3] + plane[0] * x + plane[1] * y) / -plane[2]; 105} 106 107 108#define SOLVE_PLANE(X, Y, PLANE) \ 109 ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2]) 110 111 112/* 113 * Return 1 / solve_plane(). 114 */ 115static INLINE GLfloat 116solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4]) 117{ 118 const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y; 119 if (denom == 0.0F) 120 return 0.0F; 121 else 122 return -plane[2] / denom; 123} 124 125 126 127/* 128 * Solve plane and return clamped GLchan value. 129 */ 130static INLINE GLchan 131solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4]) 132{ 133 GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2] + 0.5F; 134 if (z < 0.0F) 135 return 0; 136 else if (z > CHAN_MAXF) 137 return (GLchan) CHAN_MAXF; 138 return (GLchan) (GLint) z; 139} 140 141 142 143/* 144 * Compute how much (area) of the given pixel is inside the triangle. 145 * Vertices MUST be specified in counter-clockwise order. 146 * Return: coverage in [0, 1]. 147 */ 148static GLfloat 149compute_coveragef(const GLfloat v0[3], const GLfloat v1[3], 150 const GLfloat v2[3], GLint winx, GLint winy) 151{ 152 /* Given a position [0,3]x[0,3] return the sub-pixel sample position. 153 * Contributed by Ray Tice. 154 * 155 * Jitter sample positions - 156 * - average should be .5 in x & y for each column 157 * - each of the 16 rows and columns should be used once 158 * - the rectangle formed by the first four points 159 * should contain the other points 160 * - the distrubition should be fairly even in any given direction 161 * 162 * The pattern drawn below isn't optimal, but it's better than a regular 163 * grid. In the drawing, the center of each subpixel is surrounded by 164 * four dots. The "x" marks the jittered position relative to the 165 * subpixel center. 166 */ 167#define POS(a, b) (0.5+a*4+b)/16 168 static const GLfloat samples[16][2] = { 169 /* start with the four corners */ 170 { POS(0, 2), POS(0, 0) }, 171 { POS(3, 3), POS(0, 2) }, 172 { POS(0, 0), POS(3, 1) }, 173 { POS(3, 1), POS(3, 3) }, 174 /* continue with interior samples */ 175 { POS(1, 1), POS(0, 1) }, 176 { POS(2, 0), POS(0, 3) }, 177 { POS(0, 3), POS(1, 3) }, 178 { POS(1, 2), POS(1, 0) }, 179 { POS(2, 3), POS(1, 2) }, 180 { POS(3, 2), POS(1, 1) }, 181 { POS(0, 1), POS(2, 2) }, 182 { POS(1, 0), POS(2, 1) }, 183 { POS(2, 1), POS(2, 3) }, 184 { POS(3, 0), POS(2, 0) }, 185 { POS(1, 3), POS(3, 0) }, 186 { POS(2, 2), POS(3, 2) } 187 }; 188 189 const GLfloat x = (GLfloat) winx; 190 const GLfloat y = (GLfloat) winy; 191 const GLfloat dx0 = v1[0] - v0[0]; 192 const GLfloat dy0 = v1[1] - v0[1]; 193 const GLfloat dx1 = v2[0] - v1[0]; 194 const GLfloat dy1 = v2[1] - v1[1]; 195 const GLfloat dx2 = v0[0] - v2[0]; 196 const GLfloat dy2 = v0[1] - v2[1]; 197 GLint stop = 4, i; 198 GLfloat insideCount = 16.0F; 199 200#ifdef DEBUG 201 { 202 const GLfloat area = dx0 * dy1 - dx1 * dy0; 203 ASSERT(area >= 0.0); 204 } 205#endif 206 207 for (i = 0; i < stop; i++) { 208 const GLfloat sx = x + samples[i][0]; 209 const GLfloat sy = y + samples[i][1]; 210 const GLfloat fx0 = sx - v0[0]; 211 const GLfloat fy0 = sy - v0[1]; 212 const GLfloat fx1 = sx - v1[0]; 213 const GLfloat fy1 = sy - v1[1]; 214 const GLfloat fx2 = sx - v2[0]; 215 const GLfloat fy2 = sy - v2[1]; 216 /* cross product determines if sample is inside or outside each edge */ 217 GLfloat cross0 = (dx0 * fy0 - dy0 * fx0); 218 GLfloat cross1 = (dx1 * fy1 - dy1 * fx1); 219 GLfloat cross2 = (dx2 * fy2 - dy2 * fx2); 220 /* Check if the sample is exactly on an edge. If so, let cross be a 221 * positive or negative value depending on the direction of the edge. 222 */ 223 if (cross0 == 0.0F) 224 cross0 = dx0 + dy0; 225 if (cross1 == 0.0F) 226 cross1 = dx1 + dy1; 227 if (cross2 == 0.0F) 228 cross2 = dx2 + dy2; 229 if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) { 230 /* point is outside triangle */ 231 insideCount -= 1.0F; 232 stop = 16; 233 } 234 } 235 if (stop == 4) 236 return 1.0F; 237 else 238 return insideCount * (1.0F / 16.0F); 239} 240 241 242 243/* 244 * Compute how much (area) of the given pixel is inside the triangle. 245 * Vertices MUST be specified in counter-clockwise order. 246 * Return: coverage in [0, 15]. 247 */ 248static GLint 249compute_coveragei(const GLfloat v0[3], const GLfloat v1[3], 250 const GLfloat v2[3], GLint winx, GLint winy) 251{ 252 /* NOTE: 15 samples instead of 16. */ 253 static const GLfloat samples[15][2] = { 254 /* start with the four corners */ 255 { POS(0, 2), POS(0, 0) }, 256 { POS(3, 3), POS(0, 2) }, 257 { POS(0, 0), POS(3, 1) }, 258 { POS(3, 1), POS(3, 3) }, 259 /* continue with interior samples */ 260 { POS(1, 1), POS(0, 1) }, 261 { POS(2, 0), POS(0, 3) }, 262 { POS(0, 3), POS(1, 3) }, 263 { POS(1, 2), POS(1, 0) }, 264 { POS(2, 3), POS(1, 2) }, 265 { POS(3, 2), POS(1, 1) }, 266 { POS(0, 1), POS(2, 2) }, 267 { POS(1, 0), POS(2, 1) }, 268 { POS(2, 1), POS(2, 3) }, 269 { POS(3, 0), POS(2, 0) }, 270 { POS(1, 3), POS(3, 0) } 271 }; 272 const GLfloat x = (GLfloat) winx; 273 const GLfloat y = (GLfloat) winy; 274 const GLfloat dx0 = v1[0] - v0[0]; 275 const GLfloat dy0 = v1[1] - v0[1]; 276 const GLfloat dx1 = v2[0] - v1[0]; 277 const GLfloat dy1 = v2[1] - v1[1]; 278 const GLfloat dx2 = v0[0] - v2[0]; 279 const GLfloat dy2 = v0[1] - v2[1]; 280 GLint stop = 4, i; 281 GLint insideCount = 15; 282 283#ifdef DEBUG 284 { 285 const GLfloat area = dx0 * dy1 - dx1 * dy0; 286 ASSERT(area >= 0.0); 287 } 288#endif 289 290 for (i = 0; i < stop; i++) { 291 const GLfloat sx = x + samples[i][0]; 292 const GLfloat sy = y + samples[i][1]; 293 const GLfloat fx0 = sx - v0[0]; 294 const GLfloat fy0 = sy - v0[1]; 295 const GLfloat fx1 = sx - v1[0]; 296 const GLfloat fy1 = sy - v1[1]; 297 const GLfloat fx2 = sx - v2[0]; 298 const GLfloat fy2 = sy - v2[1]; 299 /* cross product determines if sample is inside or outside each edge */ 300 GLfloat cross0 = (dx0 * fy0 - dy0 * fx0); 301 GLfloat cross1 = (dx1 * fy1 - dy1 * fx1); 302 GLfloat cross2 = (dx2 * fy2 - dy2 * fx2); 303 /* Check if the sample is exactly on an edge. If so, let cross be a 304 * positive or negative value depending on the direction of the edge. 305 */ 306 if (cross0 == 0.0F) 307 cross0 = dx0 + dy0; 308 if (cross1 == 0.0F) 309 cross1 = dx1 + dy1; 310 if (cross2 == 0.0F) 311 cross2 = dx2 + dy2; 312 if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) { 313 /* point is outside triangle */ 314 insideCount--; 315 stop = 15; 316 } 317 } 318 if (stop == 4) 319 return 15; 320 else 321 return insideCount; 322} 323 324 325 326static void 327rgba_aa_tri(GLcontext *ctx, 328 const SWvertex *v0, 329 const SWvertex *v1, 330 const SWvertex *v2) 331{ 332#define DO_Z 333#define DO_FOG 334#define DO_RGBA 335#include "s_aatritemp.h" 336} 337 338 339static void 340index_aa_tri(GLcontext *ctx, 341 const SWvertex *v0, 342 const SWvertex *v1, 343 const SWvertex *v2) 344{ 345#define DO_Z 346#define DO_FOG 347#define DO_INDEX 348#include "s_aatritemp.h" 349} 350 351 352/* 353 * Compute mipmap level of detail. 354 */ 355static INLINE GLfloat 356compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4], 357 GLfloat invQ, GLfloat width, GLfloat height) 358{ 359 GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width; 360 GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width; 361 GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height; 362 GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height; 363 GLfloat r1 = dudx * dudx + dudy * dudy; 364 GLfloat r2 = dvdx * dvdx + dvdy * dvdy; 365 GLfloat rho2 = r1 + r2; 366 /* return log base 2 of rho */ 367 if (rho2 == 0.0F) 368 return 0.0; 369 else 370 return (GLfloat) (log(rho2) * 1.442695 * 0.5); /* 1.442695 = 1/log(2) */ 371} 372 373 374static void 375tex_aa_tri(GLcontext *ctx, 376 const SWvertex *v0, 377 const SWvertex *v1, 378 const SWvertex *v2) 379{ 380#define DO_Z 381#define DO_FOG 382#define DO_RGBA 383#define DO_TEX 384#include "s_aatritemp.h" 385} 386 387 388static void 389spec_tex_aa_tri(GLcontext *ctx, 390 const SWvertex *v0, 391 const SWvertex *v1, 392 const SWvertex *v2) 393{ 394#define DO_Z 395#define DO_FOG 396#define DO_RGBA 397#define DO_TEX 398#define DO_SPEC 399#include "s_aatritemp.h" 400} 401 402 403static void 404multitex_aa_tri(GLcontext *ctx, 405 const SWvertex *v0, 406 const SWvertex *v1, 407 const SWvertex *v2) 408{ 409#define DO_Z 410#define DO_FOG 411#define DO_RGBA 412#define DO_MULTITEX 413#include "s_aatritemp.h" 414} 415 416static void 417spec_multitex_aa_tri(GLcontext *ctx, 418 const SWvertex *v0, 419 const SWvertex *v1, 420 const SWvertex *v2) 421{ 422#define DO_Z 423#define DO_FOG 424#define DO_RGBA 425#define DO_MULTITEX 426#define DO_SPEC 427#include "s_aatritemp.h" 428} 429 430 431/* 432 * Examine GL state and set swrast->Triangle to an 433 * appropriate antialiased triangle rasterizer function. 434 */ 435void 436_mesa_set_aa_triangle_function(GLcontext *ctx) 437{ 438 ASSERT(ctx->Polygon.SmoothFlag); 439 440 if (ctx->Texture._ReallyEnabled) { 441 if (ctx->_TriangleCaps & DD_SEPARATE_SPECULAR) { 442 if (ctx->Texture._ReallyEnabled > TEXTURE0_ANY) { 443 SWRAST_CONTEXT(ctx)->Triangle = spec_multitex_aa_tri; 444 } 445 else { 446 SWRAST_CONTEXT(ctx)->Triangle = spec_tex_aa_tri; 447 } 448 } 449 else { 450 if (ctx->Texture._ReallyEnabled > TEXTURE0_ANY) { 451 SWRAST_CONTEXT(ctx)->Triangle = multitex_aa_tri; 452 } 453 else { 454 SWRAST_CONTEXT(ctx)->Triangle = tex_aa_tri; 455 } 456 } 457 } 458 else if (ctx->Visual.rgbMode) { 459 SWRAST_CONTEXT(ctx)->Triangle = rgba_aa_tri; 460 } 461 else { 462 SWRAST_CONTEXT(ctx)->Triangle = index_aa_tri; 463 } 464 465 ASSERT(SWRAST_CONTEXT(ctx)->Triangle); 466} 467