reactos/dll/opengl/mesa/src/mesa/swrast/s_aaline.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  6.5.3
   4  *
   5  * Copyright (C) 1999-2007  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 "main/glheader.h"
  27 #include "main/imports.h"
  28 #include "main/macros.h"
  29 #include "main/mtypes.h"
  30 #include "swrast/s_aaline.h"
  31 #include "swrast/s_context.h"
  32 #include "swrast/s_span.h"
  33 #include "swrast/swrast.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_RGBA - always enabled */
  63    GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];
  64    /* DO_ATTRIBS */
  65    GLfloat wPlane[4];
  66    GLfloat attrPlane[FRAG_ATTRIB_MAX][4][4];
  67    GLfloat lambda[FRAG_ATTRIB_MAX];
  68    GLfloat texWidth[FRAG_ATTRIB_MAX];
  69    GLfloat texHeight[FRAG_ATTRIB_MAX];
  70
  71    SWspan span;
  72 };
  73
  74
  75
  76 /*
  77  * Compute the equation of a plane used to interpolate line fragment data
  78  * such as color, Z, texture coords, etc.
  79  * Input: (x0, y0) and (x1,y1) are the endpoints of the line.
  80  *        z0, and z1 are the end point values to interpolate.
  81  * Output:  plane - the plane equation.
  82  *
  83  * Note: we don't really have enough parameters to specify a plane.
  84  * We take the endpoints of the line and compute a plane such that
  85  * the cross product of the line vector and the plane normal is
  86  * parallel to the projection plane.
  87  */
  88 static void
  89 compute_plane(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
  90               GLfloat z0, GLfloat z1, GLfloat plane[4])
  91 {
  92 #if 0
  93    /* original */
  94    const GLfloat px = x1 - x0;
  95    const GLfloat py = y1 - y0;
  96    const GLfloat pz = z1 - z0;
  97    const GLfloat qx = -py;
  98    const GLfloat qy = px;
  99    const GLfloat qz = 0;
 100    const GLfloat a = py * qz - pz * qy;
 101    const GLfloat b = pz * qx - px * qz;
 102    const GLfloat c = px * qy - py * qx;
 103    const GLfloat d = -(a * x0 + b * y0 + c * z0);
 104    plane[0] = a;
 105    plane[1] = b;
 106    plane[2] = c;
 107    plane[3] = d;
 108 #else
 109    /* simplified */
 110    const GLfloat px = x1 - x0;
 111    const GLfloat py = y1 - y0;
 112    const GLfloat pz = z0 - z1;
 113    const GLfloat a = pz * px;
 114    const GLfloat b = pz * py;
 115    const GLfloat c = px * px + py * py;
 116    const GLfloat d = -(a * x0 + b * y0 + c * z0);
 117    if (a == 0.0 && b == 0.0 && c == 0.0 && d == 0.0) {
 118       plane[0] = 0.0;
 119       plane[1] = 0.0;
 120       plane[2] = 1.0;
 121       plane[3] = 0.0;
 122    }
 123    else {
 124       plane[0] = a;
 125       plane[1] = b;
 126       plane[2] = c;
 127       plane[3] = d;
 128    }
 129 #endif
 130 }
 131
 132
 133 static inline void
 134 constant_plane(GLfloat value, GLfloat plane[4])
 135 {
 136    plane[0] = 0.0;
 137    plane[1] = 0.0;
 138    plane[2] = -1.0;
 139    plane[3] = value;
 140 }
 141
 142
 143 static inline GLfloat
 144 solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
 145 {
 146    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
 147    return z;
 148 }
 149
 150 #define SOLVE_PLANE(X, Y, PLANE) \
 151    ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
 152
 153
 154 /*
 155  * Return 1 / solve_plane().
 156  */
 157 static inline GLfloat
 158 solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
 159 {
 160    const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y;
 161    if (denom == 0.0)
 162       return 0.0;
 163    else
 164       return -plane[2] / denom;
 165 }
 166
 167
 168 /*
 169  * Solve plane and return clamped GLchan value.
 170  */
 171 static inline GLchan
 172 solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
 173 {
 174    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
 175 #if CHAN_TYPE == GL_FLOAT
 176    return CLAMP(z, 0.0F, CHAN_MAXF);
 177 #else
 178    if (z < 0)
 179       return 0;
 180    else if (z > CHAN_MAX)
 181       return CHAN_MAX;
 182    return (GLchan) IROUND_POS(z);
 183 #endif
 184 }
 185
 186
 187 /*
 188  * Compute mipmap level of detail.
 189  */
 190 static inline GLfloat
 191 compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
 192                GLfloat invQ, GLfloat width, GLfloat height)
 193 {
 194    GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width;
 195    GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width;
 196    GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height;
 197    GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height;
 198    GLfloat r1 = dudx * dudx + dudy * dudy;
 199    GLfloat r2 = dvdx * dvdx + dvdy * dvdy;
 200    GLfloat rho2 = r1 + r2;
 201    /* return log base 2 of rho */
 202    if (rho2 == 0.0F)
 203       return 0.0;
 204    else
 205       return (GLfloat) (LOGF(rho2) * 1.442695 * 0.5);/* 1.442695 = 1/log(2) */
 206 }
 207
 208
 209
 210
 211 /*
 212  * Fill in the samples[] array with the (x,y) subpixel positions of
 213  * xSamples * ySamples sample positions.
 214  * Note that the four corner samples are put into the first four
 215  * positions of the array.  This allows us to optimize for the common
 216  * case of all samples being inside the polygon.
 217  */
 218 static void
 219 make_sample_table(GLint xSamples, GLint ySamples, GLfloat samples[][2])
 220 {
 221    const GLfloat dx = 1.0F / (GLfloat) xSamples;
 222    const GLfloat dy = 1.0F / (GLfloat) ySamples;
 223    GLint x, y;
 224    GLint i;
 225
 226    i = 4;
 227    for (x = 0; x < xSamples; x++) {
 228       for (y = 0; y < ySamples; y++) {
 229          GLint j;
 230          if (x == 0 && y == 0) {
 231             /* lower left */
 232             j = 0;
 233          }
 234          else if (x == xSamples - 1 && y == 0) {
 235             /* lower right */
 236             j = 1;
 237          }
 238          else if (x == 0 && y == ySamples - 1) {
 239             /* upper left */
 240             j = 2;
 241          }
 242          else if (x == xSamples - 1 && y == ySamples - 1) {
 243             /* upper right */
 244             j = 3;
 245          }
 246          else {
 247             j = i++;
 248          }
 249          samples[j][0] = x * dx + 0.5F * dx;
 250          samples[j][1] = y * dy + 0.5F * dy;
 251       }
 252    }
 253 }
 254
 255
 256
 257 /*
 258  * Compute how much of the given pixel's area is inside the rectangle
 259  * defined by vertices v0, v1, v2, v3.
 260  * Vertices MUST be specified in counter-clockwise order.
 261  * Return:  coverage in [0, 1].
 262  */
 263 static GLfloat
 264 compute_coveragef(const struct LineInfo *info,
 265                   GLint winx, GLint winy)
 266 {
 267    static GLfloat samples[SUB_PIXEL * SUB_PIXEL][2];
 268    static GLboolean haveSamples = GL_FALSE;
 269    const GLfloat x = (GLfloat) winx;
 270    const GLfloat y = (GLfloat) winy;
 271    GLint stop = 4, i;
 272    GLfloat insideCount = SUB_PIXEL * SUB_PIXEL;
 273
 274    if (!haveSamples) {
 275       make_sample_table(SUB_PIXEL, SUB_PIXEL, samples);
 276       haveSamples = GL_TRUE;
 277    }
 278
 279 #if 0 /*DEBUG*/
 280    {
 281       const GLfloat area = dx0 * dy1 - dx1 * dy0;
 282       assert(area >= 0.0);
 283    }
 284 #endif
 285
 286    for (i = 0; i < stop; i++) {
 287       const GLfloat sx = x + samples[i][0];
 288       const GLfloat sy = y + samples[i][1];
 289       const GLfloat fx0 = sx - info->qx0;
 290       const GLfloat fy0 = sy - info->qy0;
 291       const GLfloat fx1 = sx - info->qx1;
 292       const GLfloat fy1 = sy - info->qy1;
 293       const GLfloat fx2 = sx - info->qx2;
 294       const GLfloat fy2 = sy - info->qy2;
 295       const GLfloat fx3 = sx - info->qx3;
 296       const GLfloat fy3 = sy - info->qy3;
 297       /* cross product determines if sample is inside or outside each edge */
 298       GLfloat cross0 = (info->ex0 * fy0 - info->ey0 * fx0);
 299       GLfloat cross1 = (info->ex1 * fy1 - info->ey1 * fx1);
 300       GLfloat cross2 = (info->ex2 * fy2 - info->ey2 * fx2);
 301       GLfloat cross3 = (info->ex3 * fy3 - info->ey3 * fx3);
 302       /* Check if the sample is exactly on an edge.  If so, let cross be a
 303        * positive or negative value depending on the direction of the edge.
 304        */
 305       if (cross0 == 0.0F)
 306          cross0 = info->ex0 + info->ey0;
 307       if (cross1 == 0.0F)
 308          cross1 = info->ex1 + info->ey1;
 309       if (cross2 == 0.0F)
 310          cross2 = info->ex2 + info->ey2;
 311       if (cross3 == 0.0F)
 312          cross3 = info->ex3 + info->ey3;
 313       if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F || cross3 < 0.0F) {
 314          /* point is outside quadrilateral */
 315          insideCount -= 1.0F;
 316          stop = SUB_PIXEL * SUB_PIXEL;
 317       }
 318    }
 319    if (stop == 4)
 320       return 1.0F;
 321    else
 322       return insideCount * (1.0F / (SUB_PIXEL * SUB_PIXEL));
 323 }
 324
 325
 326 typedef void (*plot_func)(struct gl_context *ctx, struct LineInfo *line,
 327                           int ix, int iy);
 328
 329
 330
 331 /*
 332  * Draw an AA line segment (called many times per line when stippling)
 333  */
 334 static void
 335 segment(struct gl_context *ctx,
 336         struct LineInfo *line,
 337         plot_func plot,
 338         GLfloat t0, GLfloat t1)
 339 {
 340    const GLfloat absDx = (line->dx < 0.0F) ? -line->dx : line->dx;
 341    const GLfloat absDy = (line->dy < 0.0F) ? -line->dy : line->dy;
 342    /* compute the actual segment's endpoints */
 343    const GLfloat x0 = line->x0 + t0 * line->dx;
 344    const GLfloat y0 = line->y0 + t0 * line->dy;
 345    const GLfloat x1 = line->x0 + t1 * line->dx;
 346    const GLfloat y1 = line->y0 + t1 * line->dy;
 347
 348    /* compute vertices of the line-aligned quadrilateral */
 349    line->qx0 = x0 - line->yAdj;
 350    line->qy0 = y0 + line->xAdj;
 351    line->qx1 = x0 + line->yAdj;
 352    line->qy1 = y0 - line->xAdj;
 353    line->qx2 = x1 + line->yAdj;
 354    line->qy2 = y1 - line->xAdj;
 355    line->qx3 = x1 - line->yAdj;
 356    line->qy3 = y1 + line->xAdj;
 357    /* compute the quad's edge vectors (for coverage calc) */
 358    line->ex0 = line->qx1 - line->qx0;
 359    line->ey0 = line->qy1 - line->qy0;
 360    line->ex1 = line->qx2 - line->qx1;
 361    line->ey1 = line->qy2 - line->qy1;
 362    line->ex2 = line->qx3 - line->qx2;
 363    line->ey2 = line->qy3 - line->qy2;
 364    line->ex3 = line->qx0 - line->qx3;
 365    line->ey3 = line->qy0 - line->qy3;
 366
 367    if (absDx > absDy) {
 368       /* X-major line */
 369       GLfloat dydx = line->dy / line->dx;
 370       GLfloat xLeft, xRight, yBot, yTop;
 371       GLint ix, ixRight;
 372       if (x0 < x1) {
 373          xLeft = x0 - line->halfWidth;
 374          xRight = x1 + line->halfWidth;
 375          if (line->dy >= 0.0) {
 376             yBot = y0 - 3.0F * line->halfWidth;
 377             yTop = y0 + line->halfWidth;
 378          }
 379          else {
 380             yBot = y0 - line->halfWidth;
 381             yTop = y0 + 3.0F * line->halfWidth;
 382          }
 383       }
 384       else {
 385          xLeft = x1 - line->halfWidth;
 386          xRight = x0 + line->halfWidth;
 387          if (line->dy <= 0.0) {
 388             yBot = y1 - 3.0F * line->halfWidth;
 389             yTop = y1 + line->halfWidth;
 390          }
 391          else {
 392             yBot = y1 - line->halfWidth;
 393             yTop = y1 + 3.0F * line->halfWidth;
 394          }
 395       }
 396
 397       /* scan along the line, left-to-right */
 398       ixRight = (GLint) (xRight + 1.0F);
 399
 400       /*printf("avg span height: %g\n", yTop - yBot);*/
 401       for (ix = (GLint) xLeft; ix < ixRight; ix++) {
 402          const GLint iyBot = (GLint) yBot;
 403          const GLint iyTop = (GLint) (yTop + 1.0F);
 404          GLint iy;
 405          /* scan across the line, bottom-to-top */
 406          for (iy = iyBot; iy < iyTop; iy++) {
 407             (*plot)(ctx, line, ix, iy);
 408          }
 409          yBot += dydx;
 410          yTop += dydx;
 411       }
 412    }
 413    else {
 414       /* Y-major line */
 415       GLfloat dxdy = line->dx / line->dy;
 416       GLfloat yBot, yTop, xLeft, xRight;
 417       GLint iy, iyTop;
 418       if (y0 < y1) {
 419          yBot = y0 - line->halfWidth;
 420          yTop = y1 + line->halfWidth;
 421          if (line->dx >= 0.0) {
 422             xLeft = x0 - 3.0F * line->halfWidth;
 423             xRight = x0 + line->halfWidth;
 424          }
 425          else {
 426             xLeft = x0 - line->halfWidth;
 427             xRight = x0 + 3.0F * line->halfWidth;
 428          }
 429       }
 430       else {
 431          yBot = y1 - line->halfWidth;
 432          yTop = y0 + line->halfWidth;
 433          if (line->dx <= 0.0) {
 434             xLeft = x1 - 3.0F * line->halfWidth;
 435             xRight = x1 + line->halfWidth;
 436          }
 437          else {
 438             xLeft = x1 - line->halfWidth;
 439             xRight = x1 + 3.0F * line->halfWidth;
 440          }
 441       }
 442
 443       /* scan along the line, bottom-to-top */
 444       iyTop = (GLint) (yTop + 1.0F);
 445
 446       /*printf("avg span width: %g\n", xRight - xLeft);*/
 447       for (iy = (GLint) yBot; iy < iyTop; iy++) {
 448          const GLint ixLeft = (GLint) xLeft;
 449          const GLint ixRight = (GLint) (xRight + 1.0F);
 450          GLint ix;
 451          /* scan across the line, left-to-right */
 452          for (ix = ixLeft; ix < ixRight; ix++) {
 453             (*plot)(ctx, line, ix, iy);
 454          }
 455          xLeft += dxdy;
 456          xRight += dxdy;
 457       }
 458    }
 459 }
 460
 461
 462 #define NAME(x) aa_rgba_##x
 463 #define DO_Z
 464 #include "s_aalinetemp.h"
 465
 466
 467 #define NAME(x)  aa_general_rgba_##x
 468 #define DO_Z
 469 #define DO_ATTRIBS
 470 #include "s_aalinetemp.h"
 471
 472
 473
 474 void
 475 _swrast_choose_aa_line_function(struct gl_context *ctx)
 476 {
 477    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 478
 479    ASSERT(ctx->Line.SmoothFlag);
 480
 481    if (ctx->Texture._EnabledCoordUnits != 0
 482        || (ctx->Light.Enabled &&
 483            ctx->Light.Model.ColorControl == GL_SEPARATE_SPECULAR_COLOR)
 484        || ctx->Fog.ColorSumEnabled
 485        || swrast->_FogEnabled) {
 486       swrast->Line = aa_general_rgba_line;
 487    }
 488    else {
 489       swrast->Line = aa_rgba_line;
 490    }
 491 }