src/mesa/swrast/s_aatriangle.c

   1 /* $Id: s_aatriangle.c,v 1.18 2001/05/29 15:23:15 brianp Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  3.5
   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 "mem.h"
  34 #include "mmath.h"
  35 #include "s_aatriangle.h"
  36 #include "s_context.h"
  37 #include "s_span.h"
  38
  39
  40 /*
  41  * Compute coefficients of a plane using the X,Y coords of the v0, v1, v2
  42  * vertices and the given Z values.
  43  */
  44 static INLINE void
  45 compute_plane(const GLfloat v0[], const GLfloat v1[], const GLfloat v2[],
  46               GLfloat z0, GLfloat z1, GLfloat z2, GLfloat plane[4])
  47 {
  48    const GLfloat px = v1[0] - v0[0];
  49    const GLfloat py = v1[1] - v0[1];
  50    const GLfloat pz = z1 - z0;
  51
  52    const GLfloat qx = v2[0] - v0[0];
  53    const GLfloat qy = v2[1] - v0[1];
  54    const GLfloat qz = z2 - z0;
  55
  56    const GLfloat a = py * qz - pz * qy;
  57    const GLfloat b = pz * qx - px * qz;
  58    const GLfloat c = px * qy - py * qx;
  59    const GLfloat d = -(a * v0[0] + b * v0[1] + c * z0);
  60
  61    plane[0] = a;
  62    plane[1] = b;
  63    plane[2] = c;
  64    plane[3] = d;
  65 }
  66
  67
  68 /*
  69  * Compute coefficients of a plane with a constant Z value.
  70  */
  71 static INLINE void
  72 constant_plane(GLfloat value, GLfloat plane[4])
  73 {
  74    plane[0] = 0.0;
  75    plane[1] = 0.0;
  76    plane[2] = -1.0;
  77    plane[3] = value;
  78 }
  79
  80 #define CONSTANT_PLANE(VALUE, PLANE)    \
  81 do {                                    \
  82    PLANE[0] = 0.0F;                     \
  83    PLANE[1] = 0.0F;                     \
  84    PLANE[2] = -1.0F;                    \
  85    PLANE[3] = VALUE;                    \
  86 } while (0)
  87
  88
  89
  90 /*
  91  * Solve plane equation for Z at (X,Y).
  92  */
  93 static INLINE GLfloat
  94 solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
  95 {
  96    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
  97    return z;
  98 }
  99
 100
 101 #define SOLVE_PLANE(X, Y, PLANE) \
 102    ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
 103
 104
 105 /*
 106  * Return 1 / solve_plane().
 107  */
 108 static INLINE GLfloat
 109 solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
 110 {
 111    const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y;
 112    if (denom == 0.0F)
 113       return 0.0F;
 114    else
 115       return -plane[2] / denom;
 116 }
 117
 118
 119
 120 /*
 121  * Solve plane and return clamped GLchan value.
 122  */
 123 static INLINE GLchan
 124 solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
 125 {
 126    GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2] + 0.5F;
 127    if (z < 0.0F)
 128       return 0;
 129    else if (z > CHAN_MAXF)
 130       return (GLchan) CHAN_MAXF;
 131    return (GLchan) (GLint) z;
 132 }
 133
 134
 135
 136 /*
 137  * Compute how much (area) of the given pixel is inside the triangle.
 138  * Vertices MUST be specified in counter-clockwise order.
 139  * Return:  coverage in [0, 1].
 140  */
 141 static GLfloat
 142 compute_coveragef(const GLfloat v0[3], const GLfloat v1[3],
 143                   const GLfloat v2[3], GLint winx, GLint winy)
 144 {
 145 #define B 0.125
 146    static const GLfloat samples[16][2] = {
 147       /* start with the four corners */
 148       { 0.00+B, 0.00+B },
 149       { 0.75+B, 0.00+B },
 150       { 0.00+B, 0.75+B },
 151       { 0.75+B, 0.75+B },
 152       /* continue with interior samples */
 153       { 0.25+B, 0.00+B },
 154       { 0.50+B, 0.00+B },
 155       { 0.00+B, 0.25+B },
 156       { 0.25+B, 0.25+B },
 157       { 0.50+B, 0.25+B },
 158       { 0.75+B, 0.25+B },
 159       { 0.00+B, 0.50+B },
 160       { 0.25+B, 0.50+B },
 161       { 0.50+B, 0.50+B },
 162       { 0.75+B, 0.50+B },
 163       { 0.25+B, 0.75+B },
 164       { 0.50+B, 0.75+B }
 165    };
 166    const GLfloat x = (GLfloat) winx;
 167    const GLfloat y = (GLfloat) winy;
 168    const GLfloat dx0 = v1[0] - v0[0];
 169    const GLfloat dy0 = v1[1] - v0[1];
 170    const GLfloat dx1 = v2[0] - v1[0];
 171    const GLfloat dy1 = v2[1] - v1[1];
 172    const GLfloat dx2 = v0[0] - v2[0];
 173    const GLfloat dy2 = v0[1] - v2[1];
 174    GLint stop = 4, i;
 175    GLfloat insideCount = 16.0F;
 176
 177 #ifdef DEBUG
 178    {
 179       const GLfloat area = dx0 * dy1 - dx1 * dy0;
 180       assert(area >= 0.0);
 181    }
 182 #endif
 183
 184    for (i = 0; i < stop; i++) {
 185       const GLfloat sx = x + samples[i][0];
 186       const GLfloat sy = y + samples[i][1];
 187       const GLfloat fx0 = sx - v0[0];
 188       const GLfloat fy0 = sy - v0[1];
 189       const GLfloat fx1 = sx - v1[0];
 190       const GLfloat fy1 = sy - v1[1];
 191       const GLfloat fx2 = sx - v2[0];
 192       const GLfloat fy2 = sy - v2[1];
 193       /* cross product determines if sample is inside or outside each edge */
 194       GLfloat cross0 = (dx0 * fy0 - dy0 * fx0);
 195       GLfloat cross1 = (dx1 * fy1 - dy1 * fx1);
 196       GLfloat cross2 = (dx2 * fy2 - dy2 * fx2);
 197       /* Check if the sample is exactly on an edge.  If so, let cross be a
 198        * positive or negative value depending on the direction of the edge.
 199        */
 200       if (cross0 == 0.0F)
 201          cross0 = dx0 + dy0;
 202       if (cross1 == 0.0F)
 203          cross1 = dx1 + dy1;
 204       if (cross2 == 0.0F)
 205          cross2 = dx2 + dy2;
 206       if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) {
 207          /* point is outside triangle */
 208          insideCount -= 1.0F;
 209          stop = 16;
 210       }
 211    }
 212    if (stop == 4)
 213       return 1.0F;
 214    else
 215       return insideCount * (1.0F / 16.0F);
 216 }
 217
 218
 219
 220 /*
 221  * Compute how much (area) of the given pixel is inside the triangle.
 222  * Vertices MUST be specified in counter-clockwise order.
 223  * Return:  coverage in [0, 15].
 224  */
 225 static GLint
 226 compute_coveragei(const GLfloat v0[3], const GLfloat v1[3],
 227                   const GLfloat v2[3], GLint winx, GLint winy)
 228 {
 229    /* NOTE: 15 samples instead of 16.
 230     * A better sample distribution could be used.
 231     */
 232    static const GLfloat samples[15][2] = {
 233       /* start with the four corners */
 234       { 0.00+B, 0.00+B },
 235       { 0.75+B, 0.00+B },
 236       { 0.00+B, 0.75+B },
 237       { 0.75+B, 0.75+B },
 238       /* continue with interior samples */
 239       { 0.25+B, 0.00+B },
 240       { 0.50+B, 0.00+B },
 241       { 0.00+B, 0.25+B },
 242       { 0.25+B, 0.25+B },
 243       { 0.50+B, 0.25+B },
 244       { 0.75+B, 0.25+B },
 245       { 0.00+B, 0.50+B },
 246       { 0.25+B, 0.50+B },
 247       /*{ 0.50, 0.50 },*/
 248       { 0.75+B, 0.50+B },
 249       { 0.25+B, 0.75+B },
 250       { 0.50+B, 0.75+B }
 251    };
 252    const GLfloat x = (GLfloat) winx;
 253    const GLfloat y = (GLfloat) winy;
 254    const GLfloat dx0 = v1[0] - v0[0];
 255    const GLfloat dy0 = v1[1] - v0[1];
 256    const GLfloat dx1 = v2[0] - v1[0];
 257    const GLfloat dy1 = v2[1] - v1[1];
 258    const GLfloat dx2 = v0[0] - v2[0];
 259    const GLfloat dy2 = v0[1] - v2[1];
 260    GLint stop = 4, i;
 261    GLint insideCount = 15;
 262
 263 #ifdef DEBUG
 264    {
 265       const GLfloat area = dx0 * dy1 - dx1 * dy0;
 266       assert(area >= 0.0);
 267    }
 268 #endif
 269
 270    for (i = 0; i < stop; i++) {
 271       const GLfloat sx = x + samples[i][0];
 272       const GLfloat sy = y + samples[i][1];
 273       const GLfloat fx0 = sx - v0[0];
 274       const GLfloat fy0 = sy - v0[1];
 275       const GLfloat fx1 = sx - v1[0];
 276       const GLfloat fy1 = sy - v1[1];
 277       const GLfloat fx2 = sx - v2[0];
 278       const GLfloat fy2 = sy - v2[1];
 279       /* cross product determines if sample is inside or outside each edge */
 280       GLfloat cross0 = (dx0 * fy0 - dy0 * fx0);
 281       GLfloat cross1 = (dx1 * fy1 - dy1 * fx1);
 282       GLfloat cross2 = (dx2 * fy2 - dy2 * fx2);
 283       /* Check if the sample is exactly on an edge.  If so, let cross be a
 284        * positive or negative value depending on the direction of the edge.
 285        */
 286       if (cross0 == 0.0F)
 287          cross0 = dx0 + dy0;
 288       if (cross1 == 0.0F)
 289          cross1 = dx1 + dy1;
 290       if (cross2 == 0.0F)
 291          cross2 = dx2 + dy2;
 292       if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) {
 293          /* point is outside triangle */
 294          insideCount--;
 295          stop = 15;
 296       }
 297    }
 298    if (stop == 4)
 299       return 15;
 300    else
 301       return insideCount;
 302 }
 303
 304
 305
 306 static void
 307 rgba_aa_tri(GLcontext *ctx,
 308             const SWvertex *v0,
 309             const SWvertex *v1,
 310             const SWvertex *v2)
 311 {
 312 #define DO_Z
 313 #define DO_FOG
 314 #define DO_RGBA
 315 #include "s_aatritemp.h"
 316 }
 317
 318
 319 static void
 320 index_aa_tri(GLcontext *ctx,
 321              const SWvertex *v0,
 322              const SWvertex *v1,
 323              const SWvertex *v2)
 324 {
 325 #define DO_Z
 326 #define DO_FOG
 327 #define DO_INDEX
 328 #include "s_aatritemp.h"
 329 }
 330
 331
 332 /*
 333  * Compute mipmap level of detail.
 334  */
 335 static INLINE GLfloat
 336 compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
 337                GLfloat invQ, GLfloat width, GLfloat height)
 338 {
 339    GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width;
 340    GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width;
 341    GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height;
 342    GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height;
 343    GLfloat r1 = dudx * dudx + dudy * dudy;
 344    GLfloat r2 = dvdx * dvdx + dvdy * dvdy;
 345    GLfloat rho2 = r1 + r2;
 346    /* return log base 2 of rho */
 347    if (rho2 == 0.0F)
 348       return 0.0;
 349    else
 350       return log(rho2) * 1.442695 * 0.5;       /* 1.442695 = 1/log(2) */
 351 }
 352
 353
 354 static void
 355 tex_aa_tri(GLcontext *ctx,
 356            const SWvertex *v0,
 357            const SWvertex *v1,
 358            const SWvertex *v2)
 359 {
 360 #define DO_Z
 361 #define DO_FOG
 362 #define DO_RGBA
 363 #define DO_TEX
 364 #include "s_aatritemp.h"
 365 }
 366
 367
 368 static void
 369 spec_tex_aa_tri(GLcontext *ctx,
 370                 const SWvertex *v0,
 371                 const SWvertex *v1,
 372                 const SWvertex *v2)
 373 {
 374 #define DO_Z
 375 #define DO_FOG
 376 #define DO_RGBA
 377 #define DO_TEX
 378 #define DO_SPEC
 379 #include "s_aatritemp.h"
 380 }
 381
 382
 383 static void
 384 multitex_aa_tri(GLcontext *ctx,
 385                 const SWvertex *v0,
 386                 const SWvertex *v1,
 387                 const SWvertex *v2)
 388 {
 389 #define DO_Z
 390 #define DO_FOG
 391 #define DO_RGBA
 392 #define DO_MULTITEX
 393 #include "s_aatritemp.h"
 394 }
 395
 396 static void
 397 spec_multitex_aa_tri(GLcontext *ctx,
 398                      const SWvertex *v0,
 399                      const SWvertex *v1,
 400                      const SWvertex *v2)
 401 {
 402 #define DO_Z
 403 #define DO_FOG
 404 #define DO_RGBA
 405 #define DO_MULTITEX
 406 #define DO_SPEC
 407 #include "s_aatritemp.h"
 408 }
 409
 410
 411 /*
 412  * Examine GL state and set swrast->Triangle to an
 413  * appropriate antialiased triangle rasterizer function.
 414  */
 415 void
 416 _mesa_set_aa_triangle_function(GLcontext *ctx)
 417 {
 418    ASSERT(ctx->Polygon.SmoothFlag);
 419
 420    if (ctx->Texture._ReallyEnabled) {
 421       if (ctx->_TriangleCaps & DD_SEPARATE_SPECULAR) {
 422          if (ctx->Texture._ReallyEnabled > TEXTURE0_ANY) {
 423             SWRAST_CONTEXT(ctx)->Triangle = spec_multitex_aa_tri;
 424          }
 425          else {
 426             SWRAST_CONTEXT(ctx)->Triangle = spec_tex_aa_tri;
 427          }
 428       }
 429       else {
 430          if (ctx->Texture._ReallyEnabled > TEXTURE0_ANY) {
 431             SWRAST_CONTEXT(ctx)->Triangle = multitex_aa_tri;
 432          }
 433          else {
 434             SWRAST_CONTEXT(ctx)->Triangle = tex_aa_tri;
 435          }
 436       }
 437    }
 438    else if (ctx->Visual.rgbMode) {
 439       SWRAST_CONTEXT(ctx)->Triangle = rgba_aa_tri;
 440    }
 441    else {
 442       SWRAST_CONTEXT(ctx)->Triangle = index_aa_tri;
 443    }
 444
 445    ASSERT(SWRAST_CONTEXT(ctx)->Triangle);
 446 }