reactos/lib/mesa32/src/swrast/s_aaline.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  6.1
   4  *
   5  * Copyright (C) 1999-2004  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 #include "glheader.h"
  27 #include "imports.h"
  28 #include "macros.h"
  29 #include "swrast/s_aaline.h"
  30 #include "swrast/s_context.h"
  31 #include "swrast/s_span.h"
  32 #include "swrast/swrast.h"
  33 #include "mtypes.h"
  34
  35
  36 #define SUB_PIXEL 4
  37
  38
  39 /*
  40  * Info about the AA line we're rendering
  41  */
  42 struct LineInfo
  43 {
  44    GLfloat x0, y0;        /* start */
  45    GLfloat x1, y1;        /* end */
  46    GLfloat dx, dy;        /* direction vector */
  47    GLfloat len;           /* length */
  48    GLfloat halfWidth;     /* half of line width */
  49    GLfloat xAdj, yAdj;    /* X and Y adjustment for quad corners around line */
  50    /* for coverage computation */
  51    GLfloat qx0, qy0;      /* quad vertices */
  52    GLfloat qx1, qy1;
  53    GLfloat qx2, qy2;
  54    GLfloat qx3, qy3;
  55    GLfloat ex0, ey0;      /* quad edge vectors */
  56    GLfloat ex1, ey1;
  57    GLfloat ex2, ey2;
  58    GLfloat ex3, ey3;
  59
  60    /* DO_Z */
  61    GLfloat zPlane[4];
  62    /* DO_FOG */
  63    GLfloat fPlane[4];
  64    /* DO_RGBA */
  65    GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];
  66    /* DO_INDEX */
  67    GLfloat iPlane[4];
  68    /* DO_SPEC */
  69    GLfloat srPlane[4], sgPlane[4], sbPlane[4];
  70    /* DO_TEX or DO_MULTITEX */
  71    GLfloat sPlane[MAX_TEXTURE_COORD_UNITS][4];
  72    GLfloat tPlane[MAX_TEXTURE_COORD_UNITS][4];
  73    GLfloat uPlane[MAX_TEXTURE_COORD_UNITS][4];
  74    GLfloat vPlane[MAX_TEXTURE_COORD_UNITS][4];
  75    GLfloat lambda[MAX_TEXTURE_COORD_UNITS];
  76    GLfloat texWidth[MAX_TEXTURE_COORD_UNITS];
  77    GLfloat texHeight[MAX_TEXTURE_COORD_UNITS];
  78
  79    struct sw_span span;
  80 };
  81
  82
  83
  84 /*
  85  * Compute the equation of a plane used to interpolate line fragment data
  86  * such as color, Z, texture coords, etc.
  87  * Input: (x0, y0) and (x1,y1) are the endpoints of the line.
  88  *        z0, and z1 are the end point values to interpolate.
  89  * Output:  plane - the plane equation.
  90  *
  91  * Note: we don't really have enough parameters to specify a plane.
  92  * We take the endpoints of the line and compute a plane such that
  93  * the cross product of the line vector and the plane normal is
  94  * parallel to the projection plane.
  95  */
  96 static void
  97 compute_plane(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
  98               GLfloat z0, GLfloat z1, GLfloat plane[4])
  99 {
 100 #if 0
 101    /* original */
 102    const GLfloat px = x1 - x0;
 103    const GLfloat py = y1 - y0;
 104    const GLfloat pz = z1 - z0;
 105    const GLfloat qx = -py;
 106    const GLfloat qy = px;
 107    const GLfloat qz = 0;
 108    const GLfloat a = py * qz - pz * qy;
 109    const GLfloat b = pz * qx - px * qz;
 110    const GLfloat c = px * qy - py * qx;
 111    const GLfloat d = -(a * x0 + b * y0 + c * z0);
 112    plane[0] = a;
 113    plane[1] = b;
 114    plane[2] = c;
 115    plane[3] = d;
 116 #else
 117    /* simplified */
 118    const GLfloat px = x1 - x0;
 119    const GLfloat py = y1 - y0;
 120    const GLfloat pz = z0 - z1;
 121    const GLfloat a = pz * px;
 122    const GLfloat b = pz * py;
 123    const GLfloat c = px * px + py * py;
 124    const GLfloat d = -(a * x0 + b * y0 + c * z0);
 125    if (a == 0.0 && b == 0.0 && c == 0.0 && d == 0.0) {
 126       plane[0] = 0.0;
 127       plane[1] = 0.0;
 128       plane[2] = 1.0;
 129       plane[3] = 0.0;
 130    }
 131    else {
 132       plane[0] = a;
 133       plane[1] = b;
 134       plane[2] = c;
 135       plane[3] = d;
 136    }
 137 #endif
 138 }
 139
 140
 141 static INLINE void
 142 constant_plane(GLfloat value, GLfloat plane[4])
 143 {
 144    plane[0] = 0.0;
 145    plane[1] = 0.0;
 146    plane[2] = -1.0;
 147    plane[3] = value;
 148 }
 149
 150
 151 static INLINE GLfloat
 152 solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
 153 {
 154    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
 155    return z;
 156 }
 157
 158 #define SOLVE_PLANE(X, Y, PLANE) \
 159    ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
 160
 161
 162 /*
 163  * Return 1 / solve_plane().
 164  */
 165 static INLINE GLfloat
 166 solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
 167 {
 168    const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y;
 169    if (denom == 0.0)
 170       return 0.0;
 171    else
 172       return -plane[2] / denom;
 173 }
 174
 175
 176 /*
 177  * Solve plane and return clamped GLchan value.
 178  */
 179 static INLINE GLchan
 180 solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
 181 {
 182    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
 183 #if CHAN_TYPE == GL_FLOAT
 184    return CLAMP(z, 0.0F, CHAN_MAXF);
 185 #else
 186    if (z < 0)
 187       return 0;
 188    else if (z > CHAN_MAX)
 189       return CHAN_MAX;
 190    return (GLchan) IROUND_POS(z);
 191 #endif
 192 }
 193
 194
 195 /*
 196  * Compute mipmap level of detail.
 197  */
 198 static INLINE GLfloat
 199 compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
 200                GLfloat invQ, GLfloat width, GLfloat height)
 201 {
 202    GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width;
 203    GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width;
 204    GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height;
 205    GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height;
 206    GLfloat r1 = dudx * dudx + dudy * dudy;
 207    GLfloat r2 = dvdx * dvdx + dvdy * dvdy;
 208    GLfloat rho2 = r1 + r2;
 209    /* return log base 2 of rho */
 210    if (rho2 == 0.0F)
 211       return 0.0;
 212    else
 213       return (GLfloat) (log(rho2) * 1.442695 * 0.5);/* 1.442695 = 1/log(2) */
 214 }
 215
 216
 217
 218
 219 /*
 220  * Fill in the samples[] array with the (x,y) subpixel positions of
 221  * xSamples * ySamples sample positions.
 222  * Note that the four corner samples are put into the first four
 223  * positions of the array.  This allows us to optimize for the common
 224  * case of all samples being inside the polygon.
 225  */
 226 static void
 227 make_sample_table(GLint xSamples, GLint ySamples, GLfloat samples[][2])
 228 {
 229    const GLfloat dx = 1.0F / (GLfloat) xSamples;
 230    const GLfloat dy = 1.0F / (GLfloat) ySamples;
 231    GLint x, y;
 232    GLint i;
 233
 234    i = 4;
 235    for (x = 0; x < xSamples; x++) {
 236       for (y = 0; y < ySamples; y++) {
 237          GLint j;
 238          if (x == 0 && y == 0) {
 239             /* lower left */
 240             j = 0;
 241          }
 242          else if (x == xSamples - 1 && y == 0) {
 243             /* lower right */
 244             j = 1;
 245          }
 246          else if (x == 0 && y == ySamples - 1) {
 247             /* upper left */
 248             j = 2;
 249          }
 250          else if (x == xSamples - 1 && y == ySamples - 1) {
 251             /* upper right */
 252             j = 3;
 253          }
 254          else {
 255             j = i++;
 256          }
 257          samples[j][0] = x * dx + 0.5F * dx;
 258          samples[j][1] = y * dy + 0.5F * dy;
 259       }
 260    }
 261 }
 262
 263
 264
 265 /*
 266  * Compute how much of the given pixel's area is inside the rectangle
 267  * defined by vertices v0, v1, v2, v3.
 268  * Vertices MUST be specified in counter-clockwise order.
 269  * Return:  coverage in [0, 1].
 270  */
 271 static GLfloat
 272 compute_coveragef(const struct LineInfo *info,
 273                   GLint winx, GLint winy)
 274 {
 275    static GLfloat samples[SUB_PIXEL * SUB_PIXEL][2];
 276    static GLboolean haveSamples = GL_FALSE;
 277    const GLfloat x = (GLfloat) winx;
 278    const GLfloat y = (GLfloat) winy;
 279    GLint stop = 4, i;
 280    GLfloat insideCount = SUB_PIXEL * SUB_PIXEL;
 281
 282    if (!haveSamples) {
 283       make_sample_table(SUB_PIXEL, SUB_PIXEL, samples);
 284       haveSamples = GL_TRUE;
 285    }
 286
 287 #if 0 /*DEBUG*/
 288    {
 289       const GLfloat area = dx0 * dy1 - dx1 * dy0;
 290       assert(area >= 0.0);
 291    }
 292 #endif
 293
 294    for (i = 0; i < stop; i++) {
 295       const GLfloat sx = x + samples[i][0];
 296       const GLfloat sy = y + samples[i][1];
 297       const GLfloat fx0 = sx - info->qx0;
 298       const GLfloat fy0 = sy - info->qy0;
 299       const GLfloat fx1 = sx - info->qx1;
 300       const GLfloat fy1 = sy - info->qy1;
 301       const GLfloat fx2 = sx - info->qx2;
 302       const GLfloat fy2 = sy - info->qy2;
 303       const GLfloat fx3 = sx - info->qx3;
 304       const GLfloat fy3 = sy - info->qy3;
 305       /* cross product determines if sample is inside or outside each edge */
 306       GLfloat cross0 = (info->ex0 * fy0 - info->ey0 * fx0);
 307       GLfloat cross1 = (info->ex1 * fy1 - info->ey1 * fx1);
 308       GLfloat cross2 = (info->ex2 * fy2 - info->ey2 * fx2);
 309       GLfloat cross3 = (info->ex3 * fy3 - info->ey3 * fx3);
 310       /* Check if the sample is exactly on an edge.  If so, let cross be a
 311        * positive or negative value depending on the direction of the edge.
 312        */
 313       if (cross0 == 0.0F)
 314          cross0 = info->ex0 + info->ey0;
 315       if (cross1 == 0.0F)
 316          cross1 = info->ex1 + info->ey1;
 317       if (cross2 == 0.0F)
 318          cross2 = info->ex2 + info->ey2;
 319       if (cross3 == 0.0F)
 320          cross3 = info->ex3 + info->ey3;
 321       if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F || cross3 < 0.0F) {
 322          /* point is outside quadrilateral */
 323          insideCount -= 1.0F;
 324          stop = SUB_PIXEL * SUB_PIXEL;
 325       }
 326    }
 327    if (stop == 4)
 328       return 1.0F;
 329    else
 330       return insideCount * (1.0F / (SUB_PIXEL * SUB_PIXEL));
 331 }
 332
 333
 334 /**
 335  * Compute coverage value for color index mode.
 336  * XXX this may not be quite correct.
 337  * \return coverage in [0,15].
 338  */
 339 static GLfloat
 340 compute_coveragei(const struct LineInfo *info,
 341                   GLint winx, GLint winy)
 342 {
 343    return compute_coveragef(info, winx, winy) * 15.0F;
 344 }
 345
 346
 347
 348 typedef void (*plot_func)(GLcontext *ctx, struct LineInfo *line,
 349                           int ix, int iy);
 350
 351
 352
 353 /*
 354  * Draw an AA line segment (called many times per line when stippling)
 355  */
 356 static void
 357 segment(GLcontext *ctx,
 358         struct LineInfo *line,
 359         plot_func plot,
 360         GLfloat t0, GLfloat t1)
 361 {
 362    const GLfloat absDx = (line->dx < 0.0F) ? -line->dx : line->dx;
 363    const GLfloat absDy = (line->dy < 0.0F) ? -line->dy : line->dy;
 364    /* compute the actual segment's endpoints */
 365    const GLfloat x0 = line->x0 + t0 * line->dx;
 366    const GLfloat y0 = line->y0 + t0 * line->dy;
 367    const GLfloat x1 = line->x0 + t1 * line->dx;
 368    const GLfloat y1 = line->y0 + t1 * line->dy;
 369
 370    /* compute vertices of the line-aligned quadrilateral */
 371    line->qx0 = x0 - line->yAdj;
 372    line->qy0 = y0 + line->xAdj;
 373    line->qx1 = x0 + line->yAdj;
 374    line->qy1 = y0 - line->xAdj;
 375    line->qx2 = x1 + line->yAdj;
 376    line->qy2 = y1 - line->xAdj;
 377    line->qx3 = x1 - line->yAdj;
 378    line->qy3 = y1 + line->xAdj;
 379    /* compute the quad's edge vectors (for coverage calc) */
 380    line->ex0 = line->qx1 - line->qx0;
 381    line->ey0 = line->qy1 - line->qy0;
 382    line->ex1 = line->qx2 - line->qx1;
 383    line->ey1 = line->qy2 - line->qy1;
 384    line->ex2 = line->qx3 - line->qx2;
 385    line->ey2 = line->qy3 - line->qy2;
 386    line->ex3 = line->qx0 - line->qx3;
 387    line->ey3 = line->qy0 - line->qy3;
 388
 389    if (absDx > absDy) {
 390       /* X-major line */
 391       GLfloat dydx = line->dy / line->dx;
 392       GLfloat xLeft, xRight, yBot, yTop;
 393       GLint ix, ixRight;
 394       if (x0 < x1) {
 395          xLeft = x0 - line->halfWidth;
 396          xRight = x1 + line->halfWidth;
 397          if (line->dy >= 0.0) {
 398             yBot = y0 - 3.0F * line->halfWidth;
 399             yTop = y0 + line->halfWidth;
 400          }
 401          else {
 402             yBot = y0 - line->halfWidth;
 403             yTop = y0 + 3.0F * line->halfWidth;
 404          }
 405       }
 406       else {
 407          xLeft = x1 - line->halfWidth;
 408          xRight = x0 + line->halfWidth;
 409          if (line->dy <= 0.0) {
 410             yBot = y1 - 3.0F * line->halfWidth;
 411             yTop = y1 + line->halfWidth;
 412          }
 413          else {
 414             yBot = y1 - line->halfWidth;
 415             yTop = y1 + 3.0F * line->halfWidth;
 416          }
 417       }
 418
 419       /* scan along the line, left-to-right */
 420       ixRight = (GLint) (xRight + 1.0F);
 421
 422       /*printf("avg span height: %g\n", yTop - yBot);*/
 423       for (ix = (GLint) xLeft; ix < ixRight; ix++) {
 424          const GLint iyBot = (GLint) yBot;
 425          const GLint iyTop = (GLint) (yTop + 1.0F);
 426          GLint iy;
 427          /* scan across the line, bottom-to-top */
 428          for (iy = iyBot; iy < iyTop; iy++) {
 429             (*plot)(ctx, line, ix, iy);
 430          }
 431          yBot += dydx;
 432          yTop += dydx;
 433       }
 434    }
 435    else {
 436       /* Y-major line */
 437       GLfloat dxdy = line->dx / line->dy;
 438       GLfloat yBot, yTop, xLeft, xRight;
 439       GLint iy, iyTop;
 440       if (y0 < y1) {
 441          yBot = y0 - line->halfWidth;
 442          yTop = y1 + line->halfWidth;
 443          if (line->dx >= 0.0) {
 444             xLeft = x0 - 3.0F * line->halfWidth;
 445             xRight = x0 + line->halfWidth;
 446          }
 447          else {
 448             xLeft = x0 - line->halfWidth;
 449             xRight = x0 + 3.0F * line->halfWidth;
 450          }
 451       }
 452       else {
 453          yBot = y1 - line->halfWidth;
 454          yTop = y0 + line->halfWidth;
 455          if (line->dx <= 0.0) {
 456             xLeft = x1 - 3.0F * line->halfWidth;
 457             xRight = x1 + line->halfWidth;
 458          }
 459          else {
 460             xLeft = x1 - line->halfWidth;
 461             xRight = x1 + 3.0F * line->halfWidth;
 462          }
 463       }
 464
 465       /* scan along the line, bottom-to-top */
 466       iyTop = (GLint) (yTop + 1.0F);
 467
 468       /*printf("avg span width: %g\n", xRight - xLeft);*/
 469       for (iy = (GLint) yBot; iy < iyTop; iy++) {
 470          const GLint ixLeft = (GLint) xLeft;
 471          const GLint ixRight = (GLint) (xRight + 1.0F);
 472          GLint ix;
 473          /* scan across the line, left-to-right */
 474          for (ix = ixLeft; ix < ixRight; ix++) {
 475             (*plot)(ctx, line, ix, iy);
 476          }
 477          xLeft += dxdy;
 478          xRight += dxdy;
 479       }
 480    }
 481 }
 482
 483
 484 #define NAME(x) aa_ci_##x
 485 #define DO_Z
 486 #define DO_FOG
 487 #define DO_INDEX
 488 #include "s_aalinetemp.h"
 489
 490
 491 #define NAME(x) aa_rgba_##x
 492 #define DO_Z
 493 #define DO_FOG
 494 #define DO_RGBA
 495 #include "s_aalinetemp.h"
 496
 497
 498 #define NAME(x)  aa_tex_rgba_##x
 499 #define DO_Z
 500 #define DO_FOG
 501 #define DO_RGBA
 502 #define DO_TEX
 503 #include "s_aalinetemp.h"
 504
 505
 506 #define NAME(x)  aa_multitex_rgba_##x
 507 #define DO_Z
 508 #define DO_FOG
 509 #define DO_RGBA
 510 #define DO_MULTITEX
 511 #include "s_aalinetemp.h"
 512
 513
 514 #define NAME(x)  aa_multitex_spec_##x
 515 #define DO_Z
 516 #define DO_FOG
 517 #define DO_RGBA
 518 #define DO_MULTITEX
 519 #define DO_SPEC
 520 #include "s_aalinetemp.h"
 521
 522
 523
 524 void
 525 _swrast_choose_aa_line_function(GLcontext *ctx)
 526 {
 527    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 528
 529    ASSERT(ctx->Line.SmoothFlag);
 530
 531    if (ctx->Visual.rgbMode) {
 532       /* RGBA */
 533       if (ctx->Texture._EnabledCoordUnits != 0) {
 534          if (ctx->Texture._EnabledCoordUnits > 1) {
 535             /* Multitextured! */
 536             if (ctx->Light.Model.ColorControl==GL_SEPARATE_SPECULAR_COLOR ||
 537                 ctx->Fog.ColorSumEnabled)
 538                swrast->Line = aa_multitex_spec_line;
 539             else
 540                swrast->Line = aa_multitex_rgba_line;
 541          }
 542          else {
 543             swrast->Line = aa_tex_rgba_line;
 544          }
 545       }
 546       else {
 547          swrast->Line = aa_rgba_line;
 548       }
 549    }
 550    else {
 551       /* Color Index */
 552       swrast->Line = aa_ci_line;
 553    }
 554 }