s_aatriangle.c revision 2a182a98973edc9ecf2936b1288485bb2b3fa722
1/* $Id: s_aatriangle.c,v 1.22 2002/01/27 18:32:03 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 "macros.h" 34#include "mem.h" 35#include "mmath.h" 36#include "s_aatriangle.h" 37#include "s_context.h" 38#include "s_span.h" 39 40 41/* 42 * Compute coefficients of a plane using the X,Y coords of the v0, v1, v2 43 * vertices and the given Z values. 44 * A point (x,y,z) lies on plane iff a*x+b*y+c*z+d = 0. 45 */ 46static INLINE void 47compute_plane(const GLfloat v0[], const GLfloat v1[], const GLfloat v2[], 48 GLfloat z0, GLfloat z1, GLfloat z2, GLfloat plane[4]) 49{ 50 const GLfloat px = v1[0] - v0[0]; 51 const GLfloat py = v1[1] - v0[1]; 52 const GLfloat pz = z1 - z0; 53 54 const GLfloat qx = v2[0] - v0[0]; 55 const GLfloat qy = v2[1] - v0[1]; 56 const GLfloat qz = z2 - z0; 57 58 /* Crossproduct "(a,b,c):= dv1 x dv2" is orthogonal to plane. */ 59 const GLfloat a = py * qz - pz * qy; 60 const GLfloat b = pz * qx - px * qz; 61 const GLfloat c = px * qy - py * qx; 62 /* Point on the plane = "r*(a,b,c) + w", with fixed "r" depending 63 on the distance of plane from origin and arbitrary "w" parallel 64 to the plane. */ 65 /* The scalar product "(r*(a,b,c)+w)*(a,b,c)" is "r*(a^2+b^2+c^2)", 66 which is equal to "-d" below. */ 67 const GLfloat d = -(a * v0[0] + b * v0[1] + c * z0); 68 69 plane[0] = a; 70 plane[1] = b; 71 plane[2] = c; 72 plane[3] = d; 73} 74 75 76/* 77 * Compute coefficients of a plane with a constant Z value. 78 */ 79static INLINE void 80constant_plane(GLfloat value, GLfloat plane[4]) 81{ 82 plane[0] = 0.0; 83 plane[1] = 0.0; 84 plane[2] = -1.0; 85 plane[3] = value; 86} 87 88#define CONSTANT_PLANE(VALUE, PLANE) \ 89do { \ 90 PLANE[0] = 0.0F; \ 91 PLANE[1] = 0.0F; \ 92 PLANE[2] = -1.0F; \ 93 PLANE[3] = VALUE; \ 94} while (0) 95 96 97 98/* 99 * Solve plane equation for Z at (X,Y). 100 */ 101static INLINE GLfloat 102solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4]) 103{ 104 ASSERT(plane[2] != 0.0F); 105 return (plane[3] + plane[0] * x + plane[1] * y) / -plane[2]; 106} 107 108 109#define SOLVE_PLANE(X, Y, PLANE) \ 110 ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2]) 111 112 113/* 114 * Return 1 / solve_plane(). 115 */ 116static INLINE GLfloat 117solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4]) 118{ 119 const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y; 120 if (denom == 0.0F) 121 return 0.0F; 122 else 123 return -plane[2] / denom; 124} 125 126 127 128/* 129 * Solve plane and return clamped GLchan value. 130 */ 131static INLINE GLchan 132solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4]) 133{ 134 GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2] + 0.5F; 135 if (z < 0.0F) 136 return 0; 137 else if (z > CHAN_MAXF) 138 return (GLchan) CHAN_MAXF; 139 return (GLchan) (GLint) z; 140} 141 142 143 144/* 145 * Compute how much (area) of the given pixel is inside the triangle. 146 * Vertices MUST be specified in counter-clockwise order. 147 * Return: coverage in [0, 1]. 148 */ 149static GLfloat 150compute_coveragef(const GLfloat v0[3], const GLfloat v1[3], 151 const GLfloat v2[3], GLint winx, GLint winy) 152{ 153 /* Given a position [0,3]x[0,3] return the sub-pixel sample position. 154 * Contributed by Ray Tice. 155 * 156 * Jitter sample positions - 157 * - average should be .5 in x & y for each column 158 * - each of the 16 rows and columns should be used once 159 * - the rectangle formed by the first four points 160 * should contain the other points 161 * - the distrubition should be fairly even in any given direction 162 * 163 * The pattern drawn below isn't optimal, but it's better than a regular 164 * grid. In the drawing, the center of each subpixel is surrounded by 165 * four dots. The "x" marks the jittered position relative to the 166 * subpixel center. 167 */ 168#define POS(a, b) (0.5+a*4+b)/16 169 static const GLfloat samples[16][2] = { 170 /* start with the four corners */ 171 { POS(0, 2), POS(0, 0) }, 172 { POS(3, 3), POS(0, 2) }, 173 { POS(0, 0), POS(3, 1) }, 174 { POS(3, 1), POS(3, 3) }, 175 /* continue with interior samples */ 176 { POS(1, 1), POS(0, 1) }, 177 { POS(2, 0), POS(0, 3) }, 178 { POS(0, 3), POS(1, 3) }, 179 { POS(1, 2), POS(1, 0) }, 180 { POS(2, 3), POS(1, 2) }, 181 { POS(3, 2), POS(1, 1) }, 182 { POS(0, 1), POS(2, 2) }, 183 { POS(1, 0), POS(2, 1) }, 184 { POS(2, 1), POS(2, 3) }, 185 { POS(3, 0), POS(2, 0) }, 186 { POS(1, 3), POS(3, 0) }, 187 { POS(2, 2), POS(3, 2) } 188 }; 189 190 const GLfloat x = (GLfloat) winx; 191 const GLfloat y = (GLfloat) winy; 192 const GLfloat dx0 = v1[0] - v0[0]; 193 const GLfloat dy0 = v1[1] - v0[1]; 194 const GLfloat dx1 = v2[0] - v1[0]; 195 const GLfloat dy1 = v2[1] - v1[1]; 196 const GLfloat dx2 = v0[0] - v2[0]; 197 const GLfloat dy2 = v0[1] - v2[1]; 198 GLint stop = 4, i; 199 GLfloat insideCount = 16.0F; 200 201#ifdef DEBUG 202 { 203 const GLfloat area = dx0 * dy1 - dx1 * dy0; 204 ASSERT(area >= 0.0); 205 } 206#endif 207 208 for (i = 0; i < stop; i++) { 209 const GLfloat sx = x + samples[i][0]; 210 const GLfloat sy = y + samples[i][1]; 211 const GLfloat fx0 = sx - v0[0]; 212 const GLfloat fy0 = sy - v0[1]; 213 const GLfloat fx1 = sx - v1[0]; 214 const GLfloat fy1 = sy - v1[1]; 215 const GLfloat fx2 = sx - v2[0]; 216 const GLfloat fy2 = sy - v2[1]; 217 /* cross product determines if sample is inside or outside each edge */ 218 GLfloat cross0 = (dx0 * fy0 - dy0 * fx0); 219 GLfloat cross1 = (dx1 * fy1 - dy1 * fx1); 220 GLfloat cross2 = (dx2 * fy2 - dy2 * fx2); 221 /* Check if the sample is exactly on an edge. If so, let cross be a 222 * positive or negative value depending on the direction of the edge. 223 */ 224 if (cross0 == 0.0F) 225 cross0 = dx0 + dy0; 226 if (cross1 == 0.0F) 227 cross1 = dx1 + dy1; 228 if (cross2 == 0.0F) 229 cross2 = dx2 + dy2; 230 if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) { 231 /* point is outside triangle */ 232 insideCount -= 1.0F; 233 stop = 16; 234 } 235 } 236 if (stop == 4) 237 return 1.0F; 238 else 239 return insideCount * (1.0F / 16.0F); 240} 241 242 243 244/* 245 * Compute how much (area) of the given pixel is inside the triangle. 246 * Vertices MUST be specified in counter-clockwise order. 247 * Return: coverage in [0, 15]. 248 */ 249static GLint 250compute_coveragei(const GLfloat v0[3], const GLfloat v1[3], 251 const GLfloat v2[3], GLint winx, GLint winy) 252{ 253 /* NOTE: 15 samples instead of 16. */ 254 static const GLfloat samples[15][2] = { 255 /* start with the four corners */ 256 { POS(0, 2), POS(0, 0) }, 257 { POS(3, 3), POS(0, 2) }, 258 { POS(0, 0), POS(3, 1) }, 259 { POS(3, 1), POS(3, 3) }, 260 /* continue with interior samples */ 261 { POS(1, 1), POS(0, 1) }, 262 { POS(2, 0), POS(0, 3) }, 263 { POS(0, 3), POS(1, 3) }, 264 { POS(1, 2), POS(1, 0) }, 265 { POS(2, 3), POS(1, 2) }, 266 { POS(3, 2), POS(1, 1) }, 267 { POS(0, 1), POS(2, 2) }, 268 { POS(1, 0), POS(2, 1) }, 269 { POS(2, 1), POS(2, 3) }, 270 { POS(3, 0), POS(2, 0) }, 271 { POS(1, 3), POS(3, 0) } 272 }; 273 const GLfloat x = (GLfloat) winx; 274 const GLfloat y = (GLfloat) winy; 275 const GLfloat dx0 = v1[0] - v0[0]; 276 const GLfloat dy0 = v1[1] - v0[1]; 277 const GLfloat dx1 = v2[0] - v1[0]; 278 const GLfloat dy1 = v2[1] - v1[1]; 279 const GLfloat dx2 = v0[0] - v2[0]; 280 const GLfloat dy2 = v0[1] - v2[1]; 281 GLint stop = 4, i; 282 GLint insideCount = 15; 283 284#ifdef DEBUG 285 { 286 const GLfloat area = dx0 * dy1 - dx1 * dy0; 287 ASSERT(area >= 0.0); 288 } 289#endif 290 291 for (i = 0; i < stop; i++) { 292 const GLfloat sx = x + samples[i][0]; 293 const GLfloat sy = y + samples[i][1]; 294 const GLfloat fx0 = sx - v0[0]; 295 const GLfloat fy0 = sy - v0[1]; 296 const GLfloat fx1 = sx - v1[0]; 297 const GLfloat fy1 = sy - v1[1]; 298 const GLfloat fx2 = sx - v2[0]; 299 const GLfloat fy2 = sy - v2[1]; 300 /* cross product determines if sample is inside or outside each edge */ 301 GLfloat cross0 = (dx0 * fy0 - dy0 * fx0); 302 GLfloat cross1 = (dx1 * fy1 - dy1 * fx1); 303 GLfloat cross2 = (dx2 * fy2 - dy2 * fx2); 304 /* Check if the sample is exactly on an edge. If so, let cross be a 305 * positive or negative value depending on the direction of the edge. 306 */ 307 if (cross0 == 0.0F) 308 cross0 = dx0 + dy0; 309 if (cross1 == 0.0F) 310 cross1 = dx1 + dy1; 311 if (cross2 == 0.0F) 312 cross2 = dx2 + dy2; 313 if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) { 314 /* point is outside triangle */ 315 insideCount--; 316 stop = 15; 317 } 318 } 319 if (stop == 4) 320 return 15; 321 else 322 return insideCount; 323} 324 325 326 327static void 328rgba_aa_tri(GLcontext *ctx, 329 const SWvertex *v0, 330 const SWvertex *v1, 331 const SWvertex *v2) 332{ 333#define DO_Z 334#define DO_FOG 335#define DO_RGBA 336#include "s_aatritemp.h" 337} 338 339 340static void 341index_aa_tri(GLcontext *ctx, 342 const SWvertex *v0, 343 const SWvertex *v1, 344 const SWvertex *v2) 345{ 346#define DO_Z 347#define DO_FOG 348#define DO_INDEX 349#include "s_aatritemp.h" 350} 351 352 353/* 354 * Compute mipmap level of detail. 355 */ 356static INLINE GLfloat 357compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4], 358 GLfloat invQ, GLfloat width, GLfloat height) 359{ 360 GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width; 361 GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width; 362 GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height; 363 GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height; 364 GLfloat r1 = dudx * dudx + dudy * dudy; 365 GLfloat r2 = dvdx * dvdx + dvdy * dvdy; 366 GLfloat rho2 = r1 + r2; 367 /* return log base 2 of rho */ 368 if (rho2 == 0.0F) 369 return 0.0; 370 else 371 return (GLfloat) (log(rho2) * 1.442695 * 0.5); /* 1.442695 = 1/log(2) */ 372} 373 374 375static void 376tex_aa_tri(GLcontext *ctx, 377 const SWvertex *v0, 378 const SWvertex *v1, 379 const SWvertex *v2) 380{ 381#define DO_Z 382#define DO_FOG 383#define DO_RGBA 384#define DO_TEX 385#include "s_aatritemp.h" 386} 387 388 389static void 390spec_tex_aa_tri(GLcontext *ctx, 391 const SWvertex *v0, 392 const SWvertex *v1, 393 const SWvertex *v2) 394{ 395#define DO_Z 396#define DO_FOG 397#define DO_RGBA 398#define DO_TEX 399#define DO_SPEC 400#include "s_aatritemp.h" 401} 402 403 404static void 405multitex_aa_tri(GLcontext *ctx, 406 const SWvertex *v0, 407 const SWvertex *v1, 408 const SWvertex *v2) 409{ 410#define DO_Z 411#define DO_FOG 412#define DO_RGBA 413#define DO_MULTITEX 414#include "s_aatritemp.h" 415} 416 417static void 418spec_multitex_aa_tri(GLcontext *ctx, 419 const SWvertex *v0, 420 const SWvertex *v1, 421 const SWvertex *v2) 422{ 423#define DO_Z 424#define DO_FOG 425#define DO_RGBA 426#define DO_MULTITEX 427#define DO_SPEC 428#include "s_aatritemp.h" 429} 430 431 432/* 433 * Examine GL state and set swrast->Triangle to an 434 * appropriate antialiased triangle rasterizer function. 435 */ 436void 437_mesa_set_aa_triangle_function(GLcontext *ctx) 438{ 439 ASSERT(ctx->Polygon.SmoothFlag); 440 441 if (ctx->Texture._ReallyEnabled) { 442 if (ctx->_TriangleCaps & DD_SEPARATE_SPECULAR) { 443 if (ctx->Texture._ReallyEnabled > TEXTURE0_ANY) { 444 SWRAST_CONTEXT(ctx)->Triangle = spec_multitex_aa_tri; 445 } 446 else { 447 SWRAST_CONTEXT(ctx)->Triangle = spec_tex_aa_tri; 448 } 449 } 450 else { 451 if (ctx->Texture._ReallyEnabled > TEXTURE0_ANY) { 452 SWRAST_CONTEXT(ctx)->Triangle = multitex_aa_tri; 453 } 454 else { 455 SWRAST_CONTEXT(ctx)->Triangle = tex_aa_tri; 456 } 457 } 458 } 459 else if (ctx->Visual.rgbMode) { 460 SWRAST_CONTEXT(ctx)->Triangle = rgba_aa_tri; 461 } 462 else { 463 SWRAST_CONTEXT(ctx)->Triangle = index_aa_tri; 464 } 465 466 ASSERT(SWRAST_CONTEXT(ctx)->Triangle); 467} 468