1 /* $Id: tritemp.h,v 1.2 2000/10/27 15:21:40 mholst Exp $ */ 2 3 /* 4 * Mesa 3-D graphics library 5 * Version: 2.1 6 * Copyright (C) 1995-1996 Brian Paul 7 * 8 * This library is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU Library General Public 10 * License as published by the Free Software Foundation; either 11 * version 2 of the License, or (at your option) any later version. 12 * 13 * This library is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16 * Library General Public License for more details. 17 * 18 * You should have received a copy of the GNU Library General Public 19 * License along with this library; if not, write to the Free 20 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 21 */ 22 23 /* 24 * Triangle Rasterizer Template 25 * 26 * This file is #include'd to generate custom triangle rasterizers. 27 * 28 * The following macros may be defined to indicate what auxillary information 29 * must be interplated across the triangle: 30 * INTERP_Z - if defined, interpolate Z values 31 * INTERP_RGB - if defined, interpolate RGB values 32 * INTERP_ALPHA - if defined, interpolate Alpha values 33 * INTERP_INDEX - if defined, interpolate color index values 34 * INTERP_ST - if defined, interpolate integer ST texcoords 35 * (fast, simple 2-D texture mapping) 36 * INTERP_STW - if defined, interpolate float ST texcoords and W 37 * (2-D texture maps with perspective correction) 38 * INTERP_UV - if defined, interpolate float UV texcoords too 39 * (for 3-D, 4-D? texture maps) 40 * 41 * When one can directly address pixels in the color buffer the following 42 * macros can be defined and used to compute pixel addresses during 43 * rasterization (see pRow): 44 * PIXEL_TYPE - the datatype of a pixel (GLubyte, GLushort, GLuint) 45 * BYTES_PER_ROW - number of bytes per row in the color buffer 46 * PIXEL_ADDRESS(X,Y) - returns the address of pixel at (X,Y) where 47 * Y==0 at bottom of screen and increases upward. 48 * 49 * Optionally, one may provide one-time setup code per triangle: 50 * SETUP_CODE - code which is to be executed once per triangle 51 * 52 * The following macro MUST be defined: 53 * INNER_LOOP(LEFT,RIGHT,Y) - code to write a span of pixels. 54 * Something like: 55 * 56 * for (x=LEFT; x<RIGHT;x++) { 57 * put_pixel(x,Y); 58 * // increment fixed point interpolants 59 * } 60 * 61 * This code was designed for the origin to be in the lower-left corner. 62 * 63 * Inspired by triangle rasterizer code written by Allen Akin. Thanks Allen! 64 */ 65 66 67 /*void triangle( GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv )*/ 68 { 69 typedef struct { 70 GLint v0, v1; /* Y(v0) < Y(v1) */ 71 GLfloat dx; /* X(v1) - X(v0) */ 72 GLfloat dy; /* Y(v1) - Y(v0) */ 73 GLfixed fdxdy; /* dx/dy in fixed-point */ 74 GLfixed fsx; /* first sample point x coord */ 75 GLfixed fsy; 76 GLfloat adjy; /* adjust from v[0]->fy to fsy, scaled */ 77 GLint lines; /* number of lines to be sampled on this edge */ 78 GLfixed fx0; /* fixed pt X of lower endpoint */ 79 } EdgeT; 80 81 struct vertex_buffer *VB = ctx->VB; 82 EdgeT eMaj, eTop, eBot; 83 GLfloat oneOverArea; 84 int vMin, vMid, vMax; /* vertex indexes: Y(vMin)<=Y(vMid)<=Y(vMax) */ 85 86 /* find the order of the 3 vertices along the Y axis */ 87 { 88 GLfloat y0 = VB->Win[v0][1]; 89 GLfloat y1 = VB->Win[v1][1]; 90 GLfloat y2 = VB->Win[v2][1]; 91 92 if (y0<=y1) { 93 if (y1<=y2) { 94 vMin = v0; vMid = v1; vMax = v2; /* y0<=y1<=y2 */ 95 } 96 else if (y2<=y0) { 97 vMin = v2; vMid = v0; vMax = v1; /* y2<=y0<=y1 */ 98 } 99 else { 100 vMin = v0; vMid = v2; vMax = v1; /* y0<=y2<=y1 */ 101 } 102 } 103 else { 104 if (y0<=y2) { 105 vMin = v1; vMid = v0; vMax = v2; /* y1<=y0<=y2 */ 106 } 107 else if (y2<=y1) { 108 vMin = v2; vMid = v1; vMax = v0; /* y2<=y1<=y0 */ 109 } 110 else { 111 vMin = v1; vMid = v2; vMax = v0; /* y1<=y2<=y0 */ 112 } 113 } 114 } 115 116 /* vertex/edge relationship */ 117 eMaj.v0 = vMin; eMaj.v1 = vMax; /*TODO: .v1's not needed */ 118 eTop.v0 = vMid; eTop.v1 = vMax; 119 eBot.v0 = vMin; eBot.v1 = vMid; 120 121 /* compute deltas for each edge: vertex[v1] - vertex[v0] */ 122 eMaj.dx = VB->Win[vMax][0] - VB->Win[vMin][0]; 123 eMaj.dy = VB->Win[vMax][1] - VB->Win[vMin][1]; 124 eTop.dx = VB->Win[vMax][0] - VB->Win[vMid][0]; 125 eTop.dy = VB->Win[vMax][1] - VB->Win[vMid][1]; 126 eBot.dx = VB->Win[vMid][0] - VB->Win[vMin][0]; 127 eBot.dy = VB->Win[vMid][1] - VB->Win[vMin][1]; 128 129 /* compute oneOverArea */ 130 { 131 GLfloat area = eMaj.dx * eBot.dy - eBot.dx * eMaj.dy; 132 if (area>-0.05f && area<0.05f) { 133 return; /* very small; CULLED */ 134 } 135 oneOverArea = 1.0F / area; 136 } 137 138 /* Edge setup. For a triangle strip these could be reused... */ 139 { 140 /* fixed point Y coordinates */ 141 GLfixed vMin_fx = FloatToFixed(VB->Win[vMin][0] + 0.5F); 142 GLfixed vMin_fy = FloatToFixed(VB->Win[vMin][1] - 0.5F); 143 GLfixed vMid_fx = FloatToFixed(VB->Win[vMid][0] + 0.5F); 144 GLfixed vMid_fy = FloatToFixed(VB->Win[vMid][1] - 0.5F); 145 GLfixed vMax_fy = FloatToFixed(VB->Win[vMax][1] - 0.5F); 146 147 eMaj.fsy = FixedCeil(vMin_fy); 148 eMaj.lines = FixedToInt(vMax_fy + FIXED_ONE - FIXED_EPSILON - eMaj.fsy); 149 if (eMaj.lines > 0) { 150 GLfloat dxdy = eMaj.dx / eMaj.dy; 151 eMaj.fdxdy = SignedFloatToFixed(dxdy); 152 eMaj.adjy = (GLfloat) (eMaj.fsy - vMin_fy); /* SCALED! */ 153 eMaj.fx0 = vMin_fx; 154 eMaj.fsx = eMaj.fx0 + (GLfixed) (eMaj.adjy * dxdy); 155 } 156 else { 157 return; /*CULLED*/ 158 } 159 160 eTop.fsy = FixedCeil(vMid_fy); 161 eTop.lines = FixedToInt(vMax_fy + FIXED_ONE - FIXED_EPSILON - eTop.fsy); 162 if (eTop.lines > 0) { 163 GLfloat dxdy = eTop.dx / eTop.dy; 164 eTop.fdxdy = SignedFloatToFixed(dxdy); 165 eTop.adjy = (GLfloat) (eTop.fsy - vMid_fy); /* SCALED! */ 166 eTop.fx0 = vMid_fx; 167 eTop.fsx = eTop.fx0 + (GLfixed) (eTop.adjy * dxdy); 168 } 169 170 eBot.fsy = FixedCeil(vMin_fy); 171 eBot.lines = FixedToInt(vMid_fy + FIXED_ONE - FIXED_EPSILON - eBot.fsy); 172 if (eBot.lines > 0) { 173 GLfloat dxdy = eBot.dx / eBot.dy; 174 eBot.fdxdy = SignedFloatToFixed(dxdy); 175 eBot.adjy = (GLfloat) (eBot.fsy - vMin_fy); /* SCALED! */ 176 eBot.fx0 = vMin_fx; 177 eBot.fsx = eBot.fx0 + (GLfixed) (eBot.adjy * dxdy); 178 } 179 } 180 181 /* 182 * Conceptually, we view a triangle as two subtriangles 183 * separated by a perfectly horizontal line. The edge that is 184 * intersected by this line is one with maximal absolute dy; we 185 * call it a ``major'' edge. The other two edges are the 186 * ``top'' edge (for the upper subtriangle) and the ``bottom'' 187 * edge (for the lower subtriangle). If either of these two 188 * edges is horizontal or very close to horizontal, the 189 * corresponding subtriangle might cover zero sample points; 190 * we take care to handle such cases, for performance as well 191 * as correctness. 192 * 193 * By stepping rasterization parameters along the major edge, 194 * we can avoid recomputing them at the discontinuity where 195 * the top and bottom edges meet. However, this forces us to 196 * be able to scan both left-to-right and right-to-left. 197 * Also, we must determine whether the major edge is at the 198 * left or right side of the triangle. We do this by 199 * computing the magnitude of the cross-product of the major 200 * and top edges. Since this magnitude depends on the sine of 201 * the angle between the two edges, its sign tells us whether 202 * we turn to the left or to the right when travelling along 203 * the major edge to the top edge, and from this we infer 204 * whether the major edge is on the left or the right. 205 * 206 * Serendipitously, this cross-product magnitude is also a 207 * value we need to compute the iteration parameter 208 * derivatives for the triangle, and it can be used to perform 209 * backface culling because its sign tells us whether the 210 * triangle is clockwise or counterclockwise. In this code we 211 * refer to it as ``area'' because it's also proportional to 212 * the pixel area of the triangle. 213 */ 214 215 { 216 GLint ltor; /* true if scanning left-to-right */ 217 #if INTERP_Z 218 GLfloat dzdx, dzdy; GLfixed fdzdx; 219 #endif 220 #if INTERP_RGB 221 GLfloat drdx, drdy; GLfixed fdrdx; 222 GLfloat dgdx, dgdy; GLfixed fdgdx; 223 GLfloat dbdx, dbdy; GLfixed fdbdx; 224 #endif 225 #if INTERP_ALPHA 226 GLfloat dadx, dady; GLfixed fdadx; 227 #endif 228 #if INTERP_INDEX 229 GLfloat didx, didy; GLfixed fdidx; 230 #endif 231 #if INTERP_ST 232 GLfloat dsdx, dsdy; GLfixed fdsdx; 233 GLfloat dtdx, dtdy; GLfixed fdtdx; 234 #endif 235 #if INTERP_STW 236 GLfloat dsdx, dsdy; 237 GLfloat dtdx, dtdy; 238 GLfloat dwdx, dwdy; 239 #endif 240 #if INTERP_UV 241 GLfloat dudx, dudy; 242 GLfloat dvdx, dvdy; 243 #endif 244 245 /* 246 * Execute user-supplied setup code 247 */ 248 #ifdef SETUP_CODE 249 SETUP_CODE 250 #endif 251 252 ltor = (oneOverArea < 0.0F); 253 254 /* compute d?/dx and d?/dy derivatives */ 255 #if INTERP_Z 256 { 257 GLfloat eMaj_dz, eBot_dz; 258 eMaj_dz = VB->Win[vMax][2] - VB->Win[vMin][2]; 259 eBot_dz = VB->Win[vMid][2] - VB->Win[vMin][2]; 260 dzdx = oneOverArea * (eMaj_dz * eBot.dy - eMaj.dy * eBot_dz); 261 if (dzdx>DEPTH_SCALE || dzdx<-DEPTH_SCALE) { 262 /* probably a sliver triangle */ 263 dzdx = 0.0; 264 dzdy = 0.0; 265 } 266 else { 267 dzdy = oneOverArea * (eMaj.dx * eBot_dz - eMaj_dz * eBot.dx); 268 } 269 #if DEPTH_BITS==16 270 fdzdx = SignedFloatToFixed(dzdx); 271 #else 272 fdzdx = (GLint) dzdx; 273 #endif 274 } 275 #endif 276 #if INTERP_RGB 277 { 278 GLfloat eMaj_dr, eBot_dr; 279 eMaj_dr = FixedToFloat( VB->Color[vMax][0] - VB->Color[vMin][0] ); 280 eBot_dr = FixedToFloat( VB->Color[vMid][0] - VB->Color[vMin][0] ); 281 drdx = oneOverArea * (eMaj_dr * eBot.dy - eMaj.dy * eBot_dr); 282 fdrdx = SignedFloatToFixed(drdx); 283 drdy = oneOverArea * (eMaj.dx * eBot_dr - eMaj_dr * eBot.dx); 284 } 285 { 286 GLfloat eMaj_dg, eBot_dg; 287 eMaj_dg = FixedToFloat( VB->Color[vMax][1] - VB->Color[vMin][1] ); 288 eBot_dg = FixedToFloat( VB->Color[vMid][1] - VB->Color[vMin][1] ); 289 dgdx = oneOverArea * (eMaj_dg * eBot.dy - eMaj.dy * eBot_dg); 290 fdgdx = SignedFloatToFixed(dgdx); 291 dgdy = oneOverArea * (eMaj.dx * eBot_dg - eMaj_dg * eBot.dx); 292 } 293 { 294 GLfloat eMaj_db, eBot_db; 295 eMaj_db = FixedToFloat( VB->Color[vMax][2] - VB->Color[vMin][2] ); 296 eBot_db = FixedToFloat( VB->Color[vMid][2] - VB->Color[vMin][2] ); 297 dbdx = oneOverArea * (eMaj_db * eBot.dy - eMaj.dy * eBot_db); 298 fdbdx = SignedFloatToFixed(dbdx); 299 dbdy = oneOverArea * (eMaj.dx * eBot_db - eMaj_db * eBot.dx); 300 } 301 #endif 302 #if INTERP_ALPHA 303 { 304 GLfloat eMaj_da, eBot_da; 305 eMaj_da = FixedToFloat( VB->Color[vMax][3] - VB->Color[vMin][3] ); 306 eBot_da = FixedToFloat( VB->Color[vMid][3] - VB->Color[vMin][3] ); 307 dadx = oneOverArea * (eMaj_da * eBot.dy - eMaj.dy * eBot_da); 308 fdadx = SignedFloatToFixed(dadx); 309 dady = oneOverArea * (eMaj.dx * eBot_da - eMaj_da * eBot.dx); 310 } 311 #endif 312 #if INTERP_INDEX 313 { 314 GLfloat eMaj_di, eBot_di; 315 eMaj_di = (GLint) VB->Index[vMax] - (GLint) VB->Index[vMin]; 316 eBot_di = (GLint) VB->Index[vMid] - (GLint) VB->Index[vMin]; 317 didx = oneOverArea * (eMaj_di * eBot.dy - eMaj.dy * eBot_di); 318 fdidx = SignedFloatToFixed(didx); 319 didy = oneOverArea * (eMaj.dx * eBot_di - eMaj_di * eBot.dx); 320 } 321 #endif 322 #if INTERP_ST 323 { 324 GLfloat eMaj_ds, eBot_ds; 325 eMaj_ds = (VB->TexCoord[vMax][0] - VB->TexCoord[vMin][0]) * S_SCALE; 326 eBot_ds = (VB->TexCoord[vMid][0] - VB->TexCoord[vMin][0]) * T_SCALE; 327 dsdx = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds); 328 fdsdx = SignedFloatToFixed(dsdx); 329 dsdy = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx); 330 } 331 { 332 GLfloat eMaj_dt, eBot_dt; 333 eMaj_dt = (VB->TexCoord[vMax][1] - VB->TexCoord[vMin][1]) * S_SCALE; 334 eBot_dt = (VB->TexCoord[vMid][1] - VB->TexCoord[vMin][1]) * T_SCALE; 335 dtdx = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt); 336 fdtdx = SignedFloatToFixed(dtdx); 337 dtdy = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx); 338 } 339 #endif 340 #if INTERP_STW 341 { 342 GLfloat wMax = 1.0F / VB->Clip[vMax][3]; 343 GLfloat wMin = 1.0F / VB->Clip[vMin][3]; 344 GLfloat wMid = 1.0F / VB->Clip[vMid][3]; 345 GLfloat eMaj_dw, eBot_dw; 346 GLfloat eMaj_ds, eBot_ds; 347 GLfloat eMaj_dt, eBot_dt; 348 #if INTERP_UV 349 GLfloat eMaj_du, eBot_du; 350 GLfloat eMaj_dv, eBot_dv; 351 #endif 352 eMaj_dw = wMax - wMin; 353 eBot_dw = wMid - wMin; 354 dwdx = oneOverArea * (eMaj_dw * eBot.dy - eMaj.dy * eBot_dw); 355 dwdy = oneOverArea * (eMaj.dx * eBot_dw - eMaj_dw * eBot.dx); 356 357 eMaj_ds = VB->TexCoord[vMax][0]*wMax - VB->TexCoord[vMin][0]*wMin; 358 eBot_ds = VB->TexCoord[vMid][0]*wMid - VB->TexCoord[vMin][0]*wMin; 359 dsdx = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds); 360 dsdy = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx); 361 362 eMaj_dt = VB->TexCoord[vMax][1]*wMax - VB->TexCoord[vMin][1]*wMin; 363 eBot_dt = VB->TexCoord[vMid][1]*wMid - VB->TexCoord[vMin][1]*wMin; 364 dtdx = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt); 365 dtdy = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx); 366 #if INTERP_UV 367 eMaj_du = VB->TexCoord[vMax][2]*wMax - VB->TexCoord[vMin][2]*wMin; 368 eBot_du = VB->TexCoord[vMid][2]*wMid - VB->TexCoord[vMin][2]*wMin; 369 dudx = oneOverArea * (eMaj_du * eBot.dy - eMaj.dy * eBot_du); 370 dudy = oneOverArea * (eMaj.dx * eBot_du - eMaj_du * eBot.dx); 371 372 /* Note: don't divide V component by W */ 373 eMaj_dv = VB->TexCoord[vMax][3] - VB->TexCoord[vMin][3]; 374 eBot_dv = VB->TexCoord[vMid][3] - VB->TexCoord[vMin][3]; 375 dvdx = oneOverArea * (eMaj_dv * eBot.dy - eMaj.dy * eBot_dv); 376 dvdy = oneOverArea * (eMaj.dx * eBot_dv - eMaj_dv * eBot.dx); 377 #endif 378 } 379 #endif 380 381 /* 382 * We always sample at pixel centers. However, we avoid 383 * explicit half-pixel offsets in this code by incorporating 384 * the proper offset in each of x and y during the 385 * transformation to window coordinates. 386 * 387 * We also apply the usual rasterization rules to prevent 388 * cracks and overlaps. A pixel is considered inside a 389 * subtriangle if it meets all of four conditions: it is on or 390 * to the right of the left edge, strictly to the left of the 391 * right edge, on or below the top edge, and strictly above 392 * the bottom edge. (Some edges may be degenerate.) 393 * 394 * The following discussion assumes left-to-right scanning 395 * (that is, the major edge is on the left); the right-to-left 396 * case is a straightforward variation. 397 * 398 * We start by finding the half-integral y coordinate that is 399 * at or below the top of the triangle. This gives us the 400 * first scan line that could possibly contain pixels that are 401 * inside the triangle. 402 * 403 * Next we creep down the major edge until we reach that y, 404 * and compute the corresponding x coordinate on the edge. 405 * Then we find the half-integral x that lies on or just 406 * inside the edge. This is the first pixel that might lie in 407 * the interior of the triangle. (We won't know for sure 408 * until we check the other edges.) 409 * 410 * As we rasterize the triangle, we'll step down the major 411 * edge. For each step in y, we'll move an integer number 412 * of steps in x. There are two possible x step sizes, which 413 * we'll call the ``inner'' step (guaranteed to land on the 414 * edge or inside it) and the ``outer'' step (guaranteed to 415 * land on the edge or outside it). The inner and outer steps 416 * differ by one. During rasterization we maintain an error 417 * term that indicates our distance from the true edge, and 418 * select either the inner step or the outer step, whichever 419 * gets us to the first pixel that falls inside the triangle. 420 * 421 * All parameters (z, red, etc.) as well as the buffer 422 * addresses for color and z have inner and outer step values, 423 * so that we can increment them appropriately. This method 424 * eliminates the need to adjust parameters by creeping a 425 * sub-pixel amount into the triangle at each scanline. 426 */ 427 428 { 429 int subTriangle; 430 GLfixed fx, fxLeftEdge, fxRightEdge, fdxLeftEdge, fdxRightEdge; 431 GLfixed fdxOuter; 432 int idxOuter; 433 float dxOuter; 434 GLfixed fError, fdError; 435 float adjx, adjy; 436 GLfixed fy; 437 int iy; 438 #ifdef PIXEL_ADDRESS 439 PIXEL_TYPE *pRow; 440 int dPRowOuter, dPRowInner; /* offset in bytes */ 441 #endif 442 #if INTERP_Z 443 GLdepth *zRow; 444 int dZRowOuter, dZRowInner; /* offset in bytes */ 445 GLfixed fz, fdzOuter, fdzInner; 446 #endif 447 #if INTERP_RGB 448 GLfixed fr, fdrOuter, fdrInner; 449 GLfixed fg, fdgOuter, fdgInner; 450 GLfixed fb, fdbOuter, fdbInner; 451 #endif 452 #if INTERP_ALPHA 453 GLfixed fa, fdaOuter, fdaInner; 454 #endif 455 #if INTERP_INDEX 456 GLfixed fi, fdiOuter, fdiInner; 457 #endif 458 #if INTERP_ST 459 GLfixed fs, fdsOuter, fdsInner; 460 GLfixed ft, fdtOuter, fdtInner; 461 #endif 462 #if INTERP_STW 463 GLfloat sLeft, dsOuter, dsInner; 464 GLfloat tLeft, dtOuter, dtInner; 465 GLfloat wLeft, dwOuter, dwInner; 466 #endif 467 #if INTERP_UV 468 GLfloat uLeft, duOuter, duInner; 469 GLfloat vLeft, dvOuter, dvInner; 470 #endif 471 472 for (subTriangle=0; subTriangle<=1; subTriangle++) { 473 EdgeT *eLeft, *eRight; 474 int setupLeft, setupRight; 475 int lines; 476 477 if (subTriangle==0) { 478 /* bottom half */ 479 if (ltor) { 480 eLeft = &eMaj; 481 eRight = &eBot; 482 lines = eRight->lines; 483 setupLeft = 1; 484 setupRight = 1; 485 } 486 else { 487 eLeft = &eBot; 488 eRight = &eMaj; 489 lines = eLeft->lines; 490 setupLeft = 1; 491 setupRight = 1; 492 } 493 } 494 else { 495 /* top half */ 496 if (ltor) { 497 eLeft = &eMaj; 498 eRight = &eTop; 499 lines = eRight->lines; 500 setupLeft = 0; 501 setupRight = 1; 502 } 503 else { 504 eLeft = &eTop; 505 eRight = &eMaj; 506 lines = eLeft->lines; 507 setupLeft = 1; 508 setupRight = 0; 509 } 510 if (lines==0) return; 511 } 512 513 if (setupLeft && eLeft->lines>0) { 514 GLint vLower; 515 GLfixed fsx = eLeft->fsx; 516 fx = FixedCeil(fsx); 517 fError = fx - fsx - FIXED_ONE; 518 fxLeftEdge = fsx - FIXED_EPSILON; 519 fdxLeftEdge = eLeft->fdxdy; 520 fdxOuter = FixedFloor(fdxLeftEdge - FIXED_EPSILON); 521 fdError = fdxOuter - fdxLeftEdge + FIXED_ONE; 522 idxOuter = FixedToInt(fdxOuter); 523 dxOuter = (float) idxOuter; 524 525 fy = eLeft->fsy; 526 iy = FixedToInt(fy); 527 528 adjx = (float)(fx - eLeft->fx0); /* SCALED! */ 529 adjy = eLeft->adjy; /* SCALED! */ 530 531 vLower = eLeft->v0; 532 533 #ifdef PIXEL_ADDRESS 534 { 535 pRow = PIXEL_ADDRESS( FixedToInt(fxLeftEdge), iy ); 536 dPRowOuter = -BYTES_PER_ROW + idxOuter * sizeof(PIXEL_TYPE); 537 /* negative because Y=0 at bottom and increases upward */ 538 } 539 #endif 540 /* 541 * Now we need the set of parameter (z, color, etc.) values at 542 * the point (fx, fy). This gives us properly-sampled parameter 543 * values that we can step from pixel to pixel. Furthermore, 544 * although we might have intermediate results that overflow 545 * the normal parameter range when we step temporarily outside 546 * the triangle, we shouldn't overflow or underflow for any 547 * pixel that's actually inside the triangle. 548 */ 549 550 #if INTERP_Z 551 { 552 GLfloat z0; 553 z0 = VB->Win[vLower][2] + ctx->PolygonZoffset; 554 #if DEPTH_BITS==16 555 /* interpolate fixed-pt values */ 556 fz = (GLfixed)(z0 * FIXED_SCALE + dzdx * adjx + dzdy * adjy) + FIXED_HALF; 557 fdzOuter = SignedFloatToFixed(dzdy + dxOuter * dzdx); 558 #else 559 /* interpolate depth values exactly */ 560 fz = (GLint) (z0 + dzdx*FixedToFloat(adjx) + dzdy*FixedToFloat(adjy)); 561 fdzOuter = (GLint) (dzdy + dxOuter * dzdx); 562 #endif 563 zRow = Z_ADDRESS( ctx, FixedToInt(fxLeftEdge), iy ); 564 dZRowOuter = (ctx->Buffer->Width + idxOuter) * sizeof(GLdepth); 565 } 566 #endif 567 #if INTERP_RGB 568 fr = (GLfixed)(VB->Color[vLower][0] + drdx * adjx + drdy * adjy) 569 + FIXED_HALF; 570 fdrOuter = SignedFloatToFixed(drdy + dxOuter * drdx); 571 572 fg = (GLfixed)(VB->Color[vLower][1] + dgdx * adjx + dgdy * adjy) 573 + FIXED_HALF; 574 fdgOuter = SignedFloatToFixed(dgdy + dxOuter * dgdx); 575 576 fb = (GLfixed)(VB->Color[vLower][2] + dbdx * adjx + dbdy * adjy) 577 + FIXED_HALF; 578 fdbOuter = SignedFloatToFixed(dbdy + dxOuter * dbdx); 579 #endif 580 #if INTERP_ALPHA 581 fa = (GLfixed)(VB->Color[vLower][3] + dadx * adjx + dady * adjy) 582 + FIXED_HALF; 583 fdaOuter = SignedFloatToFixed(dady + dxOuter * dadx); 584 #endif 585 #if INTERP_INDEX 586 fi = (GLfixed)(VB->Index[vLower] * FIXED_SCALE + didx * adjx 587 + didy * adjy) + FIXED_HALF; 588 fdiOuter = SignedFloatToFixed(didy + dxOuter * didx); 589 #endif 590 #if INTERP_ST 591 { 592 GLfloat s0, t0; 593 s0 = VB->TexCoord[vLower][0] * S_SCALE; 594 fs = (GLfixed)(s0 * FIXED_SCALE + dsdx * adjx + dsdy * adjy) + FIXED_HALF; 595 fdsOuter = SignedFloatToFixed(dsdy + dxOuter * dsdx); 596 t0 = VB->TexCoord[vLower][1] * T_SCALE; 597 ft = (GLfixed)(t0 * FIXED_SCALE + dtdx * adjx + dtdy * adjy) + FIXED_HALF; 598 fdtOuter = SignedFloatToFixed(dtdy + dxOuter * dtdx); 599 } 600 #endif 601 #if INTERP_STW 602 { 603 GLfloat w0 = 1.0F / VB->Clip[vLower][3]; 604 GLfloat s0, t0, u0, v0; 605 wLeft = w0 + (dwdx * adjx + dwdy * adjy) * (1.0F/FIXED_SCALE); 606 dwOuter = dwdy + dxOuter * dwdx; 607 s0 = VB->TexCoord[vLower][0] * w0; 608 sLeft = s0 + (dsdx * adjx + dsdy * adjy) * (1.0F/FIXED_SCALE); 609 dsOuter = dsdy + dxOuter * dsdx; 610 t0 = VB->TexCoord[vLower][1] * w0; 611 tLeft = t0 + (dtdx * adjx + dtdy * adjy) * (1.0F/FIXED_SCALE); 612 dtOuter = dtdy + dxOuter * dtdx; 613 #if INTERP_UV 614 u0 = VB->TexCoord[vLower][2] * w0; 615 uLeft = u0 + (dudx * adjx + dudy * adjy) * (1.0F/FIXED_SCALE); 616 duOuter = dudy + dxOuter * dudx; 617 /* Note: don't divide V component by W */ 618 v0 = VB->TexCoord[vLower][3]; 619 vLeft = v0 + (dvdx * adjx + dvdy * adjy) * (1.0F/FIXED_SCALE); 620 dvOuter = dvdy + dxOuter * dvdx; 621 #endif 622 } 623 #endif 624 625 } /*if setupLeft*/ 626 627 628 if (setupRight && eRight->lines>0) { 629 fxRightEdge = eRight->fsx - FIXED_EPSILON; 630 fdxRightEdge = eRight->fdxdy; 631 } 632 633 if (lines==0) { 634 continue; 635 } 636 637 638 /* Rasterize setup */ 639 #ifdef PIXEL_ADDRESS 640 dPRowInner = dPRowOuter + sizeof(PIXEL_TYPE); 641 #endif 642 #if INTERP_Z 643 dZRowInner = dZRowOuter + sizeof(GLdepth); 644 fdzInner = fdzOuter + fdzdx; 645 #endif 646 #if INTERP_RGB 647 fdrInner = fdrOuter + fdrdx; 648 fdgInner = fdgOuter + fdgdx; 649 fdbInner = fdbOuter + fdbdx; 650 #endif 651 #if INTERP_ALPHA 652 fdaInner = fdaOuter + fdadx; 653 #endif 654 #if INTERP_INDEX 655 fdiInner = fdiOuter + fdidx; 656 #endif 657 #if INTERP_ST 658 fdsInner = fdsOuter + fdsdx; 659 fdtInner = fdtOuter + fdtdx; 660 #endif 661 #if INTERP_STW 662 dwInner = dwOuter + dwdx; 663 dsInner = dsOuter + dsdx; 664 dtInner = dtOuter + dtdx; 665 #if INTERP_UV 666 duInner = duOuter + dudx; 667 dvInner = dvOuter + dvdx; 668 #endif 669 #endif 670 671 while (lines>0) { 672 /* initialize the span interpolants to the leftmost value */ 673 /* ff = fixed-pt fragment */ 674 #if INTERP_Z 675 GLfixed ffz = fz; 676 /*GLdepth *zp = zRow;*/ 677 #endif 678 #if INTERP_RGB 679 GLfixed ffr = fr, ffg = fg, ffb = fb; 680 #endif 681 #if INTERP_ALPHA 682 GLfixed ffa = fa; 683 #endif 684 #if INTERP_INDEX 685 GLfixed ffi = fi; 686 #endif 687 #if INTERP_ST 688 GLfixed ffs = fs, fft = ft; 689 #endif 690 #if INTERP_STW 691 GLfloat ss = sLeft, tt = tLeft, ww = wLeft; 692 #endif 693 #if INTERP_UV 694 GLfloat uu = uLeft, vv = vLeft; 695 #endif 696 GLint left = FixedToInt(fxLeftEdge); 697 GLint right = FixedToInt(fxRightEdge); 698 699 #if INTERP_RGB 700 /* need this to accomodate round-off errors */ 701 if (ffr<0) ffr = 0; 702 if (ffg<0) ffg = 0; 703 if (ffb<0) ffb = 0; 704 #endif 705 #if INTERP_ALPHA 706 if (ffa<0) ffa = 0; 707 #endif 708 #if INTERP_INDEX 709 if (ffi<0) ffi = 0; 710 #endif 711 712 INNER_LOOP( left, right, iy ); 713 714 /* 715 * Advance to the next scan line. Compute the 716 * new edge coordinates, and adjust the 717 * pixel-center x coordinate so that it stays 718 * on or inside the major edge. 719 */ 720 iy++; 721 lines--; 722 723 fxLeftEdge += fdxLeftEdge; 724 fxRightEdge += fdxRightEdge; 725 726 727 fError += fdError; 728 if (fError >= 0) { 729 fError -= FIXED_ONE; 730 #ifdef PIXEL_ADDRESS 731 pRow = (PIXEL_TYPE*) ((GLubyte*)pRow + dPRowOuter); 732 #endif 733 #if INTERP_Z 734 zRow = (GLdepth*) ((GLubyte*)zRow + dZRowOuter); 735 fz += fdzOuter; 736 #endif 737 #if INTERP_RGB 738 fr += fdrOuter; fg += fdgOuter; fb += fdbOuter; 739 #endif 740 #if INTERP_ALPHA 741 fa += fdaOuter; 742 #endif 743 #if INTERP_INDEX 744 fi += fdiOuter; 745 #endif 746 #if INTERP_ST 747 fs += fdsOuter; ft += fdtOuter; 748 #endif 749 #if INTERP_STW 750 sLeft += dsOuter; 751 tLeft += dtOuter; 752 wLeft += dwOuter; 753 #endif 754 #if INTERP_UV 755 uLeft += duOuter; 756 vLeft += dvOuter; 757 #endif 758 } 759 else { 760 #ifdef PIXEL_ADDRESS 761 pRow = (PIXEL_TYPE*) ((GLubyte*)pRow + dPRowInner); 762 #endif 763 #if INTERP_Z 764 zRow = (GLdepth*) ((GLubyte*)zRow + dZRowInner); 765 fz += fdzInner; 766 #endif 767 #if INTERP_RGB 768 fr += fdrInner; fg += fdgInner; fb += fdbInner; 769 #endif 770 #if INTERP_ALPHA 771 fa += fdaInner; 772 #endif 773 #if INTERP_INDEX 774 fi += fdiInner; 775 #endif 776 #if INTERP_ST 777 fs += fdsInner; ft += fdtInner; 778 #endif 779 #if INTERP_STW 780 sLeft += dsInner; 781 tLeft += dtInner; 782 wLeft += dwInner; 783 #endif 784 #if INTERP_UV 785 uLeft += duInner; 786 vLeft += dvInner; 787 #endif 788 } 789 } /*while lines>0*/ 790 791 } /* for subTriangle */ 792 793 } 794 } 795 } 796 797 #undef SETUP_CODE 798 #undef INNER_LOOP 799 800 #undef PIXEL_TYPE 801 #undef BYTES_PER_ROW 802 #undef PIXEL_ADDRESS 803 804 #undef INTERP_Z 805 #undef INTERP_RGB 806 #undef INTERP_ALPHA 807 #undef INTERP_INDEX 808 #undef INTERP_ST 809 #undef INTERP_STW 810 #undef INTERP_UV 811 812 #undef S_SCALE 813 #undef T_SCALE 814