src/mesa/swrast/s_aatriangle.c

   1 /* $Id: s_aatriangle.c,v 1.11 2001/03/28 21:37:24 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 "mmath.h"
  34 #include "s_aatriangle.h"
  35 #include "s_context.h"
  36 #include "s_span.h"
  37
  38
  39 /*
  40  * Compute coefficients of a plane using the X,Y coords of the v0, v1, v2
  41  * vertices and the given Z values.
  42  */
  43 static INLINE void
  44 compute_plane(const GLfloat v0[], const GLfloat v1[], const GLfloat v2[],
  45               GLfloat z0, GLfloat z1, GLfloat z2, GLfloat plane[4])
  46 {
  47    const GLfloat px = v1[0] - v0[0];
  48    const GLfloat py = v1[1] - v0[1];
  49    const GLfloat pz = z1 - z0;
  50
  51    const GLfloat qx = v2[0] - v0[0];
  52    const GLfloat qy = v2[1] - v0[1];
  53    const GLfloat qz = z2 - z0;
  54
  55    const GLfloat a = py * qz - pz * qy;
  56    const GLfloat b = pz * qx - px * qz;
  57    const GLfloat c = px * qy - py * qx;
  58    const GLfloat d = -(a * v0[0] + b * v0[1] + c * z0);
  59
  60    plane[0] = a;
  61    plane[1] = b;
  62    plane[2] = c;
  63    plane[3] = d;
  64 }
  65
  66
  67 /*
  68  * Compute coefficients of a plane with a constant Z value.
  69  */
  70 static INLINE void
  71 constant_plane(GLfloat value, GLfloat plane[4])
  72 {
  73    plane[0] = 0.0;
  74    plane[1] = 0.0;
  75    plane[2] = -1.0;
  76    plane[3] = value;
  77 }
  78
  79 #define CONSTANT_PLANE(VALUE, PLANE)    \
  80 do {                                    \
  81    PLANE[0] = 0.0F;                     \
  82    PLANE[1] = 0.0F;                     \
  83    PLANE[2] = -1.0F;                    \
  84    PLANE[3] = VALUE;                    \
  85 } while (0)
  86
  87
  88
  89 /*
  90  * Solve plane equation for Z at (X,Y).
  91  */
  92 static INLINE GLfloat
  93 solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
  94 {
  95    GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
  96    return z;
  97 }
  98
  99
 100 #define SOLVE_PLANE(X, Y, PLANE) \
 101    ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
 102
 103
 104 /*
 105  * Return 1 / solve_plane().
 106  */
 107 static INLINE GLfloat
 108 solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
 109 {
 110    GLfloat z = -plane[2] / (plane[3] + plane[0] * x + plane[1] * y);
 111    return z;
 112 }
 113
 114
 115
 116 /*
 117  * Solve plane and return clamped GLchan value.
 118  */
 119 static INLINE GLchan
 120 solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
 121 {
 122    GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2] + 0.5F;
 123    if (z < 0.0F)
 124       return 0;
 125    else if (z > CHAN_MAXF)
 126       return (GLchan) CHAN_MAXF;
 127    return (GLchan) (GLint) z;
 128 }
 129
 130
 131
 132 /*
 133  * Compute how much (area) of the given pixel is inside the triangle.
 134  * Vertices MUST be specified in counter-clockwise order.
 135  * Return:  coverage in [0, 1].
 136  */
 137 static GLfloat
 138 compute_coveragef(const GLfloat v0[3], const GLfloat v1[3],
 139                   const GLfloat v2[3], GLint winx, GLint winy)
 140 {
 141 #define B 0.125
 142    static const GLfloat samples[16][2] = {
 143       /* start with the four corners */
 144       { 0.00+B, 0.00+B },
 145       { 0.75+B, 0.00+B },
 146       { 0.00+B, 0.75+B },
 147       { 0.75+B, 0.75+B },
 148       /* continue with interior samples */
 149       { 0.25+B, 0.00+B },
 150       { 0.50+B, 0.00+B },
 151       { 0.00+B, 0.25+B },
 152       { 0.25+B, 0.25+B },
 153       { 0.50+B, 0.25+B },
 154       { 0.75+B, 0.25+B },
 155       { 0.00+B, 0.50+B },
 156       { 0.25+B, 0.50+B },
 157       { 0.50+B, 0.50+B },
 158       { 0.75+B, 0.50+B },
 159       { 0.25+B, 0.75+B },
 160       { 0.50+B, 0.75+B }
 161    };
 162    const GLfloat x = (GLfloat) winx;
 163    const GLfloat y = (GLfloat) winy;
 164    const GLfloat dx0 = v1[0] - v0[0];
 165    const GLfloat dy0 = v1[1] - v0[1];
 166    const GLfloat dx1 = v2[0] - v1[0];
 167    const GLfloat dy1 = v2[1] - v1[1];
 168    const GLfloat dx2 = v0[0] - v2[0];
 169    const GLfloat dy2 = v0[1] - v2[1];
 170    GLint stop = 4, i;
 171    GLfloat insideCount = 16.0F;
 172
 173 #ifdef DEBUG
 174    {
 175       const GLfloat area = dx0 * dy1 - dx1 * dy0;
 176       assert(area >= 0.0);
 177    }
 178 #endif
 179
 180    for (i = 0; i < stop; i++) {
 181       const GLfloat sx = x + samples[i][0];
 182       const GLfloat sy = y + samples[i][1];
 183       const GLfloat fx0 = sx - v0[0];
 184       const GLfloat fy0 = sy - v0[1];
 185       const GLfloat fx1 = sx - v1[0];
 186       const GLfloat fy1 = sy - v1[1];
 187       const GLfloat fx2 = sx - v2[0];
 188       const GLfloat fy2 = sy - v2[1];
 189       /* cross product determines if sample is inside or outside each edge */
 190       GLfloat cross0 = (dx0 * fy0 - dy0 * fx0);
 191       GLfloat cross1 = (dx1 * fy1 - dy1 * fx1);
 192       GLfloat cross2 = (dx2 * fy2 - dy2 * fx2);
 193       /* Check if the sample is exactly on an edge.  If so, let cross be a
 194        * positive or negative value depending on the direction of the edge.
 195        */
 196       if (cross0 == 0.0F)
 197          cross0 = dx0 + dy0;
 198       if (cross1 == 0.0F)
 199          cross1 = dx1 + dy1;
 200       if (cross2 == 0.0F)
 201          cross2 = dx2 + dy2;
 202       if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) {
 203          /* point is outside triangle */
 204          insideCount -= 1.0F;
 205          stop = 16;
 206       }
 207    }
 208    if (stop == 4)
 209       return 1.0F;
 210    else
 211       return insideCount * (1.0F / 16.0F);
 212 }
 213
 214
 215
 216 /*
 217  * Compute how much (area) of the given pixel is inside the triangle.
 218  * Vertices MUST be specified in counter-clockwise order.
 219  * Return:  coverage in [0, 15].
 220  */
 221 static GLint
 222 compute_coveragei(const GLfloat v0[3], const GLfloat v1[3],
 223                   const GLfloat v2[3], GLint winx, GLint winy)
 224 {
 225    /* NOTE: 15 samples instead of 16.
 226     * A better sample distribution could be used.
 227     */
 228    static const GLfloat samples[15][2] = {
 229       /* start with the four corners */
 230       { 0.00+B, 0.00+B },
 231       { 0.75+B, 0.00+B },
 232       { 0.00+B, 0.75+B },
 233       { 0.75+B, 0.75+B },
 234       /* continue with interior samples */
 235       { 0.25+B, 0.00+B },
 236       { 0.50+B, 0.00+B },
 237       { 0.00+B, 0.25+B },
 238       { 0.25+B, 0.25+B },
 239       { 0.50+B, 0.25+B },
 240       { 0.75+B, 0.25+B },
 241       { 0.00+B, 0.50+B },
 242       { 0.25+B, 0.50+B },
 243       /*{ 0.50, 0.50 },*/
 244       { 0.75+B, 0.50+B },
 245       { 0.25+B, 0.75+B },
 246       { 0.50+B, 0.75+B }
 247    };
 248    const GLfloat x = (GLfloat) winx;
 249    const GLfloat y = (GLfloat) winy;
 250    const GLfloat dx0 = v1[0] - v0[0];
 251    const GLfloat dy0 = v1[1] - v0[1];
 252    const GLfloat dx1 = v2[0] - v1[0];
 253    const GLfloat dy1 = v2[1] - v1[1];
 254    const GLfloat dx2 = v0[0] - v2[0];
 255    const GLfloat dy2 = v0[1] - v2[1];
 256    GLint stop = 4, i;
 257    GLint insideCount = 15;
 258
 259 #ifdef DEBUG
 260    {
 261       const GLfloat area = dx0 * dy1 - dx1 * dy0;
 262       assert(area >= 0.0);
 263    }
 264 #endif
 265
 266    for (i = 0; i < stop; i++) {
 267       const GLfloat sx = x + samples[i][0];
 268       const GLfloat sy = y + samples[i][1];
 269       const GLfloat fx0 = sx - v0[0];
 270       const GLfloat fy0 = sy - v0[1];
 271       const GLfloat fx1 = sx - v1[0];
 272       const GLfloat fy1 = sy - v1[1];
 273       const GLfloat fx2 = sx - v2[0];
 274       const GLfloat fy2 = sy - v2[1];
 275       /* cross product determines if sample is inside or outside each edge */
 276       GLfloat cross0 = (dx0 * fy0 - dy0 * fx0);
 277       GLfloat cross1 = (dx1 * fy1 - dy1 * fx1);
 278       GLfloat cross2 = (dx2 * fy2 - dy2 * fx2);
 279       /* Check if the sample is exactly on an edge.  If so, let cross be a
 280        * positive or negative value depending on the direction of the edge.
 281        */
 282       if (cross0 == 0.0F)
 283          cross0 = dx0 + dy0;
 284       if (cross1 == 0.0F)
 285          cross1 = dx1 + dy1;
 286       if (cross2 == 0.0F)
 287          cross2 = dx2 + dy2;
 288       if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) {
 289          /* point is outside triangle */
 290          insideCount--;
 291          stop = 15;
 292       }
 293    }
 294    if (stop == 4)
 295       return 15;
 296    else
 297       return insideCount;
 298 }
 299
 300
 301
 302 static void
 303 rgba_aa_tri(GLcontext *ctx,
 304             const SWvertex *v0,
 305             const SWvertex *v1,
 306             const SWvertex *v2)
 307 {
 308 #define DO_Z
 309 #define DO_RGBA
 310 #include "s_aatritemp.h"
 311 }
 312
 313
 314 static void
 315 index_aa_tri(GLcontext *ctx,
 316              const SWvertex *v0,
 317              const SWvertex *v1,
 318              const SWvertex *v2)
 319 {
 320 #define DO_Z
 321 #define DO_INDEX
 322 #include "s_aatritemp.h"
 323 }
 324
 325
 326 /*
 327  * Compute mipmap level of detail.
 328  */
 329 static INLINE GLfloat
 330 compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
 331                GLfloat invQ, GLfloat width, GLfloat height)
 332 {
 333    GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width;
 334    GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width;
 335    GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height;
 336    GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height;
 337    GLfloat r1 = dudx * dudx + dudy * dudy;
 338    GLfloat r2 = dvdx * dvdx + dvdy * dvdy;
 339    GLfloat rho2 = r1 + r2;
 340    /* return log base 2 of rho */
 341    return log(rho2) * 1.442695 * 0.5;       /* 1.442695 = 1/log(2) */
 342 }
 343
 344
 345 static void
 346 tex_aa_tri(GLcontext *ctx,
 347            const SWvertex *v0,
 348            const SWvertex *v1,
 349            const SWvertex *v2)
 350 {
 351 #define DO_Z
 352 #define DO_RGBA
 353 #define DO_TEX
 354 #include "s_aatritemp.h"
 355 }
 356
 357
 358 static void
 359 spec_tex_aa_tri(GLcontext *ctx,
 360                 const SWvertex *v0,
 361                 const SWvertex *v1,
 362                 const SWvertex *v2)
 363 {
 364 #define DO_Z
 365 #define DO_RGBA
 366 #define DO_TEX
 367 #define DO_SPEC
 368 #include "s_aatritemp.h"
 369 }
 370
 371
 372 static void
 373 multitex_aa_tri(GLcontext *ctx,
 374                 const SWvertex *v0,
 375                 const SWvertex *v1,
 376                 const SWvertex *v2)
 377 {
 378 #define DO_Z
 379 #define DO_RGBA
 380 #define DO_MULTITEX
 381 #include "s_aatritemp.h"
 382 }
 383
 384 static void
 385 spec_multitex_aa_tri(GLcontext *ctx,
 386                      const SWvertex *v0,
 387                      const SWvertex *v1,
 388                      const SWvertex *v2)
 389 {
 390 #define DO_Z
 391 #define DO_RGBA
 392 #define DO_MULTITEX
 393 #define DO_SPEC
 394 #include "s_aatritemp.h"
 395 }
 396
 397
 398 /*
 399  * Examine GL state and set swrast->Triangle to an
 400  * appropriate antialiased triangle rasterizer function.
 401  */
 402 void
 403 _mesa_set_aa_triangle_function(GLcontext *ctx)
 404 {
 405    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 406    ASSERT(ctx->Polygon.SmoothFlag);
 407
 408    if (ctx->Texture._ReallyEnabled) {
 409       if (ctx->_TriangleCaps & DD_SEPERATE_SPECULAR) {
 410          if (swrast->_MultiTextureEnabled) {
 411             SWRAST_CONTEXT(ctx)->Triangle = spec_multitex_aa_tri;
 412          }
 413          else {
 414             SWRAST_CONTEXT(ctx)->Triangle = spec_tex_aa_tri;
 415          }
 416       }
 417       else {
 418          if (swrast->_MultiTextureEnabled) {
 419             SWRAST_CONTEXT(ctx)->Triangle = multitex_aa_tri;
 420          }
 421          else {
 422             SWRAST_CONTEXT(ctx)->Triangle = tex_aa_tri;
 423          }
 424       }
 425    }
 426    else if (ctx->Visual.rgbMode) {
 427       SWRAST_CONTEXT(ctx)->Triangle = rgba_aa_tri;
 428    }
 429    else {
 430       SWRAST_CONTEXT(ctx)->Triangle = index_aa_tri;
 431    }
 432
 433    ASSERT(SWRAST_CONTEXT(ctx)->Triangle);
 434 }