dll/opengl/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 #include <precomp.h>
  26
  27 #define SUB_PIXEL 4
  28
  29
  30 /*
  31  * Info about the AA line we're rendering
  32  */
  33 struct LineInfo
  34 {
  35    GLfloat x0, y0;        /* start */
  36    GLfloat x1, y1;        /* end */
  37    GLfloat dx, dy;        /* direction vector */
  38    GLfloat len;           /* length */
  39    GLfloat halfWidth;     /* half of line width */
  40    GLfloat xAdj, yAdj;    /* X and Y adjustment for quad corners around line */
  41    /* for coverage computation */
  42    GLfloat qx0, qy0;      /* quad vertices */
  43    GLfloat qx1, qy1;
  44    GLfloat qx2, qy2;
  45    GLfloat qx3, qy3;
  46    GLfloat ex0, ey0;      /* quad edge vectors */
  47    GLfloat ex1, ey1;
  48    GLfloat ex2, ey2;
  49    GLfloat ex3, ey3;
  50
  51    /* DO_Z */
  52    GLfloat zPlane[4];
  53    /* DO_RGBA - always enabled */
  54    GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];
  55    /* DO_ATTRIBS */
  56    GLfloat wPlane[4];
  57    GLfloat attrPlane[FRAG_ATTRIB_MAX][4][4];
  58    GLfloat lambda[FRAG_ATTRIB_MAX];
  59    GLfloat texWidth[FRAG_ATTRIB_MAX];
  60    GLfloat texHeight[FRAG_ATTRIB_MAX];
  61
  62    SWspan span;
  63 };
  64
  65
  66
  67 /*
  68  * Compute the equation of a plane used to interpolate line fragment data
  69  * such as color, Z, texture coords, etc.
  70  * Input: (x0, y0) and (x1,y1) are the endpoints of the line.
  71  *        z0, and z1 are the end point values to interpolate.
  72  * Output:  plane - the plane equation.
  73  *
  74  * Note: we don't really have enough parameters to specify a plane.
  75  * We take the endpoints of the line and compute a plane such that
  76  * the cross product of the line vector and the plane normal is
  77  * parallel to the projection plane.
  78  */
  79 static void
  80 compute_plane(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
  81               GLfloat z0, GLfloat z1, GLfloat plane[4])
  82 {
  83 #if 0
  84    /* original */
  85    const GLfloat px = x1 - x0;
  86    const GLfloat py = y1 - y0;
  87    const GLfloat pz = z1 - z0;
  88    const GLfloat qx = -py;
  89    const GLfloat qy = px;
  90    const GLfloat qz = 0;
  91    const GLfloat a = py * qz - pz * qy;
  92    const GLfloat b = pz * qx - px * qz;
  93    const GLfloat c = px * qy - py * qx;
  94    const GLfloat d = -(a * x0 + b * y0 + c * z0);
  95    plane[0] = a;
  96    plane[1] = b;
  97    plane[2] = c;
  98    plane[3] = d;
  99 #else
 100    /* simplified */
 101    const GLfloat px = x1 - x0;
 102    const GLfloat py = y1 - y0;
 103    const GLfloat pz = z0 - z1;
 104    const GLfloat a = pz * px;
 105    const GLfloat b = pz * py;
 106    const GLfloat c = px * px + py * py;
 107    const GLfloat d = -(a * x0 + b * y0 + c * z0);
 108    if (a == 0.0 && b == 0.0 && c == 0.0 && d == 0.0) {
 109       plane[0] = 0.0;
 110       plane[1] = 0.0;
 111       plane[2] = 1.0;
 112       plane[3] = 0.0;
 113    }
 114    else {
 115       plane[0] = a;
 116       plane[1] = b;
 117       plane[2] = c;
 118       plane[3] = d;
 119    }
 120 #endif
 121 }
 122
 123
 124 static inline void
 125 constant_plane(GLfloat value, GLfloat plane[4])
 126 {
 127    plane[0] = 0.0;
 128    plane[1] = 0.0;
 129    plane[2] = -1.0;
 130    plane[3] = value;
 131 }
 132
 133
 134 static inline GLfloat
 135 solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
 136 {
 137    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
 138    return z;
 139 }
 140
 141 #define SOLVE_PLANE(X, Y, PLANE) \
 142    ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
 143
 144
 145 /*
 146  * Return 1 / solve_plane().
 147  */
 148 static inline GLfloat
 149 solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
 150 {
 151    const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y;
 152    if (denom == 0.0)
 153       return 0.0;
 154    else
 155       return -plane[2] / denom;
 156 }
 157
 158
 159 /*
 160  * Solve plane and return clamped GLchan value.
 161  */
 162 static inline GLchan
 163 solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
 164 {
 165    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
 166 #if CHAN_TYPE == GL_FLOAT
 167    return CLAMP(z, 0.0F, CHAN_MAXF);
 168 #else
 169    if (z < 0)
 170       return 0;
 171    else if (z > CHAN_MAX)
 172       return CHAN_MAX;
 173    return (GLchan) IROUND_POS(z);
 174 #endif
 175 }
 176
 177
 178 /*
 179  * Compute mipmap level of detail.
 180  */
 181 static inline GLfloat
 182 compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
 183                GLfloat invQ, GLfloat width, GLfloat height)
 184 {
 185    GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width;
 186    GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width;
 187    GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height;
 188    GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height;
 189    GLfloat r1 = dudx * dudx + dudy * dudy;
 190    GLfloat r2 = dvdx * dvdx + dvdy * dvdy;
 191    GLfloat rho2 = r1 + r2;
 192    /* return log base 2 of rho */
 193    if (rho2 == 0.0F)
 194       return 0.0;
 195    else
 196       return (GLfloat) (LOGF(rho2) * 1.442695 * 0.5);/* 1.442695 = 1/log(2) */
 197 }
 198
 199
 200
 201
 202 /*
 203  * Fill in the samples[] array with the (x,y) subpixel positions of
 204  * xSamples * ySamples sample positions.
 205  * Note that the four corner samples are put into the first four
 206  * positions of the array.  This allows us to optimize for the common
 207  * case of all samples being inside the polygon.
 208  */
 209 static void
 210 make_sample_table(GLint xSamples, GLint ySamples, GLfloat samples[][2])
 211 {
 212    const GLfloat dx = 1.0F / (GLfloat) xSamples;
 213    const GLfloat dy = 1.0F / (GLfloat) ySamples;
 214    GLint x, y;
 215    GLint i;
 216
 217    i = 4;
 218    for (x = 0; x < xSamples; x++) {
 219       for (y = 0; y < ySamples; y++) {
 220          GLint j;
 221          if (x == 0 && y == 0) {
 222             /* lower left */
 223             j = 0;
 224          }
 225          else if (x == xSamples - 1 && y == 0) {
 226             /* lower right */
 227             j = 1;
 228          }
 229          else if (x == 0 && y == ySamples - 1) {
 230             /* upper left */
 231             j = 2;
 232          }
 233          else if (x == xSamples - 1 && y == ySamples - 1) {
 234             /* upper right */
 235             j = 3;
 236          }
 237          else {
 238             j = i++;
 239          }
 240          samples[j][0] = x * dx + 0.5F * dx;
 241          samples[j][1] = y * dy + 0.5F * dy;
 242       }
 243    }
 244 }
 245
 246
 247
 248 /*
 249  * Compute how much of the given pixel's area is inside the rectangle
 250  * defined by vertices v0, v1, v2, v3.
 251  * Vertices MUST be specified in counter-clockwise order.
 252  * Return:  coverage in [0, 1].
 253  */
 254 static GLfloat
 255 compute_coveragef(const struct LineInfo *info,
 256                   GLint winx, GLint winy)
 257 {
 258    static GLfloat samples[SUB_PIXEL * SUB_PIXEL][2];
 259    static GLboolean haveSamples = GL_FALSE;
 260    const GLfloat x = (GLfloat) winx;
 261    const GLfloat y = (GLfloat) winy;
 262    GLint stop = 4, i;
 263    GLfloat insideCount = SUB_PIXEL * SUB_PIXEL;
 264
 265    if (!haveSamples) {
 266       make_sample_table(SUB_PIXEL, SUB_PIXEL, samples);
 267       haveSamples = GL_TRUE;
 268    }
 269
 270 #if 0 /*DEBUG*/
 271    {
 272       const GLfloat area = dx0 * dy1 - dx1 * dy0;
 273       assert(area >= 0.0);
 274    }
 275 #endif
 276
 277    for (i = 0; i < stop; i++) {
 278       const GLfloat sx = x + samples[i][0];
 279       const GLfloat sy = y + samples[i][1];
 280       const GLfloat fx0 = sx - info->qx0;
 281       const GLfloat fy0 = sy - info->qy0;
 282       const GLfloat fx1 = sx - info->qx1;
 283       const GLfloat fy1 = sy - info->qy1;
 284       const GLfloat fx2 = sx - info->qx2;
 285       const GLfloat fy2 = sy - info->qy2;
 286       const GLfloat fx3 = sx - info->qx3;
 287       const GLfloat fy3 = sy - info->qy3;
 288       /* cross product determines if sample is inside or outside each edge */
 289       GLfloat cross0 = (info->ex0 * fy0 - info->ey0 * fx0);
 290       GLfloat cross1 = (info->ex1 * fy1 - info->ey1 * fx1);
 291       GLfloat cross2 = (info->ex2 * fy2 - info->ey2 * fx2);
 292       GLfloat cross3 = (info->ex3 * fy3 - info->ey3 * fx3);
 293       /* Check if the sample is exactly on an edge.  If so, let cross be a
 294        * positive or negative value depending on the direction of the edge.
 295        */
 296       if (cross0 == 0.0F)
 297          cross0 = info->ex0 + info->ey0;
 298       if (cross1 == 0.0F)
 299          cross1 = info->ex1 + info->ey1;
 300       if (cross2 == 0.0F)
 301          cross2 = info->ex2 + info->ey2;
 302       if (cross3 == 0.0F)
 303          cross3 = info->ex3 + info->ey3;
 304       if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F || cross3 < 0.0F) {
 305          /* point is outside quadrilateral */
 306          insideCount -= 1.0F;
 307          stop = SUB_PIXEL * SUB_PIXEL;
 308       }
 309    }
 310    if (stop == 4)
 311       return 1.0F;
 312    else
 313       return insideCount * (1.0F / (SUB_PIXEL * SUB_PIXEL));
 314 }
 315
 316
 317 typedef void (*plot_func)(struct gl_context *ctx, struct LineInfo *line,
 318                           int ix, int iy);
 319
 320
 321
 322 /*
 323  * Draw an AA line segment (called many times per line when stippling)
 324  */
 325 static void
 326 segment(struct gl_context *ctx,
 327         struct LineInfo *line,
 328         plot_func plot,
 329         GLfloat t0, GLfloat t1)
 330 {
 331    const GLfloat absDx = (line->dx < 0.0F) ? -line->dx : line->dx;
 332    const GLfloat absDy = (line->dy < 0.0F) ? -line->dy : line->dy;
 333    /* compute the actual segment's endpoints */
 334    const GLfloat x0 = line->x0 + t0 * line->dx;
 335    const GLfloat y0 = line->y0 + t0 * line->dy;
 336    const GLfloat x1 = line->x0 + t1 * line->dx;
 337    const GLfloat y1 = line->y0 + t1 * line->dy;
 338
 339    /* compute vertices of the line-aligned quadrilateral */
 340    line->qx0 = x0 - line->yAdj;
 341    line->qy0 = y0 + line->xAdj;
 342    line->qx1 = x0 + line->yAdj;
 343    line->qy1 = y0 - line->xAdj;
 344    line->qx2 = x1 + line->yAdj;
 345    line->qy2 = y1 - line->xAdj;
 346    line->qx3 = x1 - line->yAdj;
 347    line->qy3 = y1 + line->xAdj;
 348    /* compute the quad's edge vectors (for coverage calc) */
 349    line->ex0 = line->qx1 - line->qx0;
 350    line->ey0 = line->qy1 - line->qy0;
 351    line->ex1 = line->qx2 - line->qx1;
 352    line->ey1 = line->qy2 - line->qy1;
 353    line->ex2 = line->qx3 - line->qx2;
 354    line->ey2 = line->qy3 - line->qy2;
 355    line->ex3 = line->qx0 - line->qx3;
 356    line->ey3 = line->qy0 - line->qy3;
 357
 358    if (absDx > absDy) {
 359       /* X-major line */
 360       GLfloat dydx = line->dy / line->dx;
 361       GLfloat xLeft, xRight, yBot, yTop;
 362       GLint ix, ixRight;
 363       if (x0 < x1) {
 364          xLeft = x0 - line->halfWidth;
 365          xRight = x1 + line->halfWidth;
 366          if (line->dy >= 0.0) {
 367             yBot = y0 - 3.0F * line->halfWidth;
 368             yTop = y0 + line->halfWidth;
 369          }
 370          else {
 371             yBot = y0 - line->halfWidth;
 372             yTop = y0 + 3.0F * line->halfWidth;
 373          }
 374       }
 375       else {
 376          xLeft = x1 - line->halfWidth;
 377          xRight = x0 + line->halfWidth;
 378          if (line->dy <= 0.0) {
 379             yBot = y1 - 3.0F * line->halfWidth;
 380             yTop = y1 + line->halfWidth;
 381          }
 382          else {
 383             yBot = y1 - line->halfWidth;
 384             yTop = y1 + 3.0F * line->halfWidth;
 385          }
 386       }
 387
 388       /* scan along the line, left-to-right */
 389       ixRight = (GLint) (xRight + 1.0F);
 390
 391       /*printf("avg span height: %g\n", yTop - yBot);*/
 392       for (ix = (GLint) xLeft; ix < ixRight; ix++) {
 393          const GLint iyBot = (GLint) yBot;
 394          const GLint iyTop = (GLint) (yTop + 1.0F);
 395          GLint iy;
 396          /* scan across the line, bottom-to-top */
 397          for (iy = iyBot; iy < iyTop; iy++) {
 398             (*plot)(ctx, line, ix, iy);
 399          }
 400          yBot += dydx;
 401          yTop += dydx;
 402       }
 403    }
 404    else {
 405       /* Y-major line */
 406       GLfloat dxdy = line->dx / line->dy;
 407       GLfloat yBot, yTop, xLeft, xRight;
 408       GLint iy, iyTop;
 409       if (y0 < y1) {
 410          yBot = y0 - line->halfWidth;
 411          yTop = y1 + line->halfWidth;
 412          if (line->dx >= 0.0) {
 413             xLeft = x0 - 3.0F * line->halfWidth;
 414             xRight = x0 + line->halfWidth;
 415          }
 416          else {
 417             xLeft = x0 - line->halfWidth;
 418             xRight = x0 + 3.0F * line->halfWidth;
 419          }
 420       }
 421       else {
 422          yBot = y1 - line->halfWidth;
 423          yTop = y0 + line->halfWidth;
 424          if (line->dx <= 0.0) {
 425             xLeft = x1 - 3.0F * line->halfWidth;
 426             xRight = x1 + line->halfWidth;
 427          }
 428          else {
 429             xLeft = x1 - line->halfWidth;
 430             xRight = x1 + 3.0F * line->halfWidth;
 431          }
 432       }
 433
 434       /* scan along the line, bottom-to-top */
 435       iyTop = (GLint) (yTop + 1.0F);
 436
 437       /*printf("avg span width: %g\n", xRight - xLeft);*/
 438       for (iy = (GLint) yBot; iy < iyTop; iy++) {
 439          const GLint ixLeft = (GLint) xLeft;
 440          const GLint ixRight = (GLint) (xRight + 1.0F);
 441          GLint ix;
 442          /* scan across the line, left-to-right */
 443          for (ix = ixLeft; ix < ixRight; ix++) {
 444             (*plot)(ctx, line, ix, iy);
 445          }
 446          xLeft += dxdy;
 447          xRight += dxdy;
 448       }
 449    }
 450 }
 451
 452
 453 #define NAME(x) aa_rgba_##x
 454 #define DO_Z
 455 #include "s_aalinetemp.h"
 456
 457
 458 #define NAME(x)  aa_general_rgba_##x
 459 #define DO_Z
 460 #define DO_ATTRIBS
 461 #include "s_aalinetemp.h"
 462
 463
 464
 465 void
 466 _swrast_choose_aa_line_function(struct gl_context *ctx)
 467 {
 468    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 469
 470    ASSERT(ctx->Line.SmoothFlag);
 471
 472    if (ctx->Texture._EnabledCoord
 473        || swrast->_FogEnabled) {
 474       swrast->Line = aa_general_rgba_line;
 475    }
 476    else {
 477       swrast->Line = aa_rgba_line;
 478    }
 479 }