src/mesa/swrast/s_aatriangle.c

   1 /* $Id: s_aatriangle.c,v 1.28 2003/01/22 15:03:09 brianp Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  5.1
   6  *
   7  * Copyright (C) 1999-2003  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 "glheader.h"
  34 #include "colormac.h"
  35 #include "macros.h"
  36 #include "imports.h"
  37 #include "mmath.h"
  38 #include "s_aatriangle.h"
  39 #include "s_context.h"
  40 #include "s_span.h"
  41
  42
  43 /*
  44  * Compute coefficients of a plane using the X,Y coords of the v0, v1, v2
  45  * vertices and the given Z values.
  46  * A point (x,y,z) lies on plane iff a*x+b*y+c*z+d = 0.
  47  */
  48 static INLINE void
  49 compute_plane(const GLfloat v0[], const GLfloat v1[], const GLfloat v2[],
  50               GLfloat z0, GLfloat z1, GLfloat z2, GLfloat plane[4])
  51 {
  52    const GLfloat px = v1[0] - v0[0];
  53    const GLfloat py = v1[1] - v0[1];
  54    const GLfloat pz = z1 - z0;
  55
  56    const GLfloat qx = v2[0] - v0[0];
  57    const GLfloat qy = v2[1] - v0[1];
  58    const GLfloat qz = z2 - z0;
  59
  60    /* Crossproduct "(a,b,c):= dv1 x dv2" is orthogonal to plane. */
  61    const GLfloat a = py * qz - pz * qy;
  62    const GLfloat b = pz * qx - px * qz;
  63    const GLfloat c = px * qy - py * qx;
  64    /* Point on the plane = "r*(a,b,c) + w", with fixed "r" depending
  65       on the distance of plane from origin and arbitrary "w" parallel
  66       to the plane. */
  67    /* The scalar product "(r*(a,b,c)+w)*(a,b,c)" is "r*(a^2+b^2+c^2)",
  68       which is equal to "-d" below. */
  69    const GLfloat d = -(a * v0[0] + b * v0[1] + c * z0);
  70
  71    plane[0] = a;
  72    plane[1] = b;
  73    plane[2] = c;
  74    plane[3] = d;
  75 }
  76
  77
  78 /*
  79  * Compute coefficients of a plane with a constant Z value.
  80  */
  81 static INLINE void
  82 constant_plane(GLfloat value, GLfloat plane[4])
  83 {
  84    plane[0] = 0.0;
  85    plane[1] = 0.0;
  86    plane[2] = -1.0;
  87    plane[3] = value;
  88 }
  89
  90 #define CONSTANT_PLANE(VALUE, PLANE)    \
  91 do {                                    \
  92    PLANE[0] = 0.0F;                     \
  93    PLANE[1] = 0.0F;                     \
  94    PLANE[2] = -1.0F;                    \
  95    PLANE[3] = VALUE;                    \
  96 } while (0)
  97
  98
  99
 100 /*
 101  * Solve plane equation for Z at (X,Y).
 102  */
 103 static INLINE GLfloat
 104 solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
 105 {
 106    ASSERT(plane[2] != 0.0F);
 107    return (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
 108 }
 109
 110
 111 #define SOLVE_PLANE(X, Y, PLANE) \
 112    ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
 113
 114
 115 /*
 116  * Return 1 / solve_plane().
 117  */
 118 static INLINE GLfloat
 119 solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
 120 {
 121    const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y;
 122    if (denom == 0.0F)
 123       return 0.0F;
 124    else
 125       return -plane[2] / denom;
 126 }
 127
 128
 129 /*
 130  * Solve plane and return clamped GLchan value.
 131  */
 132 static INLINE GLchan
 133 solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
 134 {
 135    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
 136 #if CHAN_TYPE == GL_FLOAT
 137    return CLAMP(z, 0.0F, CHAN_MAXF);
 138 #else
 139    if (z < 0)
 140       return 0;
 141    else if (z > CHAN_MAX)
 142       return CHAN_MAX;
 143    return (GLchan) IROUND_POS(z);
 144 #endif
 145 }
 146
 147
 148
 149 /*
 150  * Compute how much (area) of the given pixel is inside the triangle.
 151  * Vertices MUST be specified in counter-clockwise order.
 152  * Return:  coverage in [0, 1].
 153  */
 154 static GLfloat
 155 compute_coveragef(const GLfloat v0[3], const GLfloat v1[3],
 156                   const GLfloat v2[3], GLint winx, GLint winy)
 157 {
 158    /* Given a position [0,3]x[0,3] return the sub-pixel sample position.
 159     * Contributed by Ray Tice.
 160     *
 161     * Jitter sample positions -
 162     * - average should be .5 in x & y for each column
 163     * - each of the 16 rows and columns should be used once
 164     * - the rectangle formed by the first four points
 165     *   should contain the other points
 166     * - the distrubition should be fairly even in any given direction
 167     *
 168     * The pattern drawn below isn't optimal, but it's better than a regular
 169     * grid.  In the drawing, the center of each subpixel is surrounded by
 170     * four dots.  The "x" marks the jittered position relative to the
 171     * subpixel center.
 172     */
 173 #define POS(a, b) (0.5+a*4+b)/16
 174    static const GLfloat samples[16][2] = {
 175       /* start with the four corners */
 176       { POS(0, 2), POS(0, 0) },
 177       { POS(3, 3), POS(0, 2) },
 178       { POS(0, 0), POS(3, 1) },
 179       { POS(3, 1), POS(3, 3) },
 180       /* continue with interior samples */
 181       { POS(1, 1), POS(0, 1) },
 182       { POS(2, 0), POS(0, 3) },
 183       { POS(0, 3), POS(1, 3) },
 184       { POS(1, 2), POS(1, 0) },
 185       { POS(2, 3), POS(1, 2) },
 186       { POS(3, 2), POS(1, 1) },
 187       { POS(0, 1), POS(2, 2) },
 188       { POS(1, 0), POS(2, 1) },
 189       { POS(2, 1), POS(2, 3) },
 190       { POS(3, 0), POS(2, 0) },
 191       { POS(1, 3), POS(3, 0) },
 192       { POS(2, 2), POS(3, 2) }
 193    };
 194
 195    const GLfloat x = (GLfloat) winx;
 196    const GLfloat y = (GLfloat) winy;
 197    const GLfloat dx0 = v1[0] - v0[0];
 198    const GLfloat dy0 = v1[1] - v0[1];
 199    const GLfloat dx1 = v2[0] - v1[0];
 200    const GLfloat dy1 = v2[1] - v1[1];
 201    const GLfloat dx2 = v0[0] - v2[0];
 202    const GLfloat dy2 = v0[1] - v2[1];
 203    GLint stop = 4, i;
 204    GLfloat insideCount = 16.0F;
 205
 206 #ifdef DEBUG
 207    {
 208       const GLfloat area = dx0 * dy1 - dx1 * dy0;
 209       ASSERT(area >= 0.0);
 210    }
 211 #endif
 212
 213    for (i = 0; i < stop; i++) {
 214       const GLfloat sx = x + samples[i][0];
 215       const GLfloat sy = y + samples[i][1];
 216       const GLfloat fx0 = sx - v0[0];
 217       const GLfloat fy0 = sy - v0[1];
 218       const GLfloat fx1 = sx - v1[0];
 219       const GLfloat fy1 = sy - v1[1];
 220       const GLfloat fx2 = sx - v2[0];
 221       const GLfloat fy2 = sy - v2[1];
 222       /* cross product determines if sample is inside or outside each edge */
 223       GLfloat cross0 = (dx0 * fy0 - dy0 * fx0);
 224       GLfloat cross1 = (dx1 * fy1 - dy1 * fx1);
 225       GLfloat cross2 = (dx2 * fy2 - dy2 * fx2);
 226       /* Check if the sample is exactly on an edge.  If so, let cross be a
 227        * positive or negative value depending on the direction of the edge.
 228        */
 229       if (cross0 == 0.0F)
 230          cross0 = dx0 + dy0;
 231       if (cross1 == 0.0F)
 232          cross1 = dx1 + dy1;
 233       if (cross2 == 0.0F)
 234          cross2 = dx2 + dy2;
 235       if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) {
 236          /* point is outside triangle */
 237          insideCount -= 1.0F;
 238          stop = 16;
 239       }
 240    }
 241    if (stop == 4)
 242       return 1.0F;
 243    else
 244       return insideCount * (1.0F / 16.0F);
 245 }
 246
 247
 248
 249 /*
 250  * Compute how much (area) of the given pixel is inside the triangle.
 251  * Vertices MUST be specified in counter-clockwise order.
 252  * Return:  coverage in [0, 15].
 253  */
 254 static GLint
 255 compute_coveragei(const GLfloat v0[3], const GLfloat v1[3],
 256                   const GLfloat v2[3], GLint winx, GLint winy)
 257 {
 258    /* NOTE: 15 samples instead of 16. */
 259    static const GLfloat samples[15][2] = {
 260       /* start with the four corners */
 261       { POS(0, 2), POS(0, 0) },
 262       { POS(3, 3), POS(0, 2) },
 263       { POS(0, 0), POS(3, 1) },
 264       { POS(3, 1), POS(3, 3) },
 265       /* continue with interior samples */
 266       { POS(1, 1), POS(0, 1) },
 267       { POS(2, 0), POS(0, 3) },
 268       { POS(0, 3), POS(1, 3) },
 269       { POS(1, 2), POS(1, 0) },
 270       { POS(2, 3), POS(1, 2) },
 271       { POS(3, 2), POS(1, 1) },
 272       { POS(0, 1), POS(2, 2) },
 273       { POS(1, 0), POS(2, 1) },
 274       { POS(2, 1), POS(2, 3) },
 275       { POS(3, 0), POS(2, 0) },
 276       { POS(1, 3), POS(3, 0) }
 277    };
 278    const GLfloat x = (GLfloat) winx;
 279    const GLfloat y = (GLfloat) winy;
 280    const GLfloat dx0 = v1[0] - v0[0];
 281    const GLfloat dy0 = v1[1] - v0[1];
 282    const GLfloat dx1 = v2[0] - v1[0];
 283    const GLfloat dy1 = v2[1] - v1[1];
 284    const GLfloat dx2 = v0[0] - v2[0];
 285    const GLfloat dy2 = v0[1] - v2[1];
 286    GLint stop = 4, i;
 287    GLint insideCount = 15;
 288
 289 #ifdef DEBUG
 290    {
 291       const GLfloat area = dx0 * dy1 - dx1 * dy0;
 292       ASSERT(area >= 0.0);
 293    }
 294 #endif
 295
 296    for (i = 0; i < stop; i++) {
 297       const GLfloat sx = x + samples[i][0];
 298       const GLfloat sy = y + samples[i][1];
 299       const GLfloat fx0 = sx - v0[0];
 300       const GLfloat fy0 = sy - v0[1];
 301       const GLfloat fx1 = sx - v1[0];
 302       const GLfloat fy1 = sy - v1[1];
 303       const GLfloat fx2 = sx - v2[0];
 304       const GLfloat fy2 = sy - v2[1];
 305       /* cross product determines if sample is inside or outside each edge */
 306       GLfloat cross0 = (dx0 * fy0 - dy0 * fx0);
 307       GLfloat cross1 = (dx1 * fy1 - dy1 * fx1);
 308       GLfloat cross2 = (dx2 * fy2 - dy2 * fx2);
 309       /* Check if the sample is exactly on an edge.  If so, let cross be a
 310        * positive or negative value depending on the direction of the edge.
 311        */
 312       if (cross0 == 0.0F)
 313          cross0 = dx0 + dy0;
 314       if (cross1 == 0.0F)
 315          cross1 = dx1 + dy1;
 316       if (cross2 == 0.0F)
 317          cross2 = dx2 + dy2;
 318       if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) {
 319          /* point is outside triangle */
 320          insideCount--;
 321          stop = 15;
 322       }
 323    }
 324    if (stop == 4)
 325       return 15;
 326    else
 327       return insideCount;
 328 }
 329
 330
 331
 332 static void
 333 rgba_aa_tri(GLcontext *ctx,
 334             const SWvertex *v0,
 335             const SWvertex *v1,
 336             const SWvertex *v2)
 337 {
 338 #define DO_Z
 339 #define DO_FOG
 340 #define DO_RGBA
 341 #include "s_aatritemp.h"
 342 }
 343
 344
 345 static void
 346 index_aa_tri(GLcontext *ctx,
 347              const SWvertex *v0,
 348              const SWvertex *v1,
 349              const SWvertex *v2)
 350 {
 351 #define DO_Z
 352 #define DO_FOG
 353 #define DO_INDEX
 354 #include "s_aatritemp.h"
 355 }
 356
 357
 358 /*
 359  * Compute mipmap level of detail.
 360  * XXX we should really include the R coordinate in this computation
 361  * in order to do 3-D texture mipmapping.
 362  */
 363 static INLINE GLfloat
 364 compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
 365                const GLfloat qPlane[4], GLfloat cx, GLfloat cy,
 366                GLfloat invQ, GLfloat texWidth, GLfloat texHeight)
 367 {
 368    const GLfloat s = solve_plane(cx, cy, sPlane);
 369    const GLfloat t = solve_plane(cx, cy, tPlane);
 370    const GLfloat invQ_x1 = solve_plane_recip(cx+1.0F, cy, qPlane);
 371    const GLfloat invQ_y1 = solve_plane_recip(cx, cy+1.0F, qPlane);
 372    const GLfloat s_x1 = s - sPlane[0] / sPlane[2];
 373    const GLfloat s_y1 = s - sPlane[1] / sPlane[2];
 374    const GLfloat t_x1 = t - tPlane[0] / tPlane[2];
 375    const GLfloat t_y1 = t - tPlane[1] / tPlane[2];
 376    GLfloat dsdx = s_x1 * invQ_x1 - s * invQ;
 377    GLfloat dsdy = s_y1 * invQ_y1 - s * invQ;
 378    GLfloat dtdx = t_x1 * invQ_x1 - t * invQ;
 379    GLfloat dtdy = t_y1 * invQ_y1 - t * invQ;
 380    GLfloat maxU, maxV, rho, lambda;
 381    dsdx = FABSF(dsdx);
 382    dsdy = FABSF(dsdy);
 383    dtdx = FABSF(dtdx);
 384    dtdy = FABSF(dtdy);
 385    maxU = MAX2(dsdx, dsdy) * texWidth;
 386    maxV = MAX2(dtdx, dtdy) * texHeight;
 387    rho = MAX2(maxU, maxV);
 388    lambda = LOG2(rho);
 389    return lambda;
 390 }
 391
 392
 393 static void
 394 tex_aa_tri(GLcontext *ctx,
 395            const SWvertex *v0,
 396            const SWvertex *v1,
 397            const SWvertex *v2)
 398 {
 399 #define DO_Z
 400 #define DO_FOG
 401 #define DO_RGBA
 402 #define DO_TEX
 403 #include "s_aatritemp.h"
 404 }
 405
 406
 407 static void
 408 spec_tex_aa_tri(GLcontext *ctx,
 409                 const SWvertex *v0,
 410                 const SWvertex *v1,
 411                 const SWvertex *v2)
 412 {
 413 #define DO_Z
 414 #define DO_FOG
 415 #define DO_RGBA
 416 #define DO_TEX
 417 #define DO_SPEC
 418 #include "s_aatritemp.h"
 419 }
 420
 421
 422 static void
 423 multitex_aa_tri(GLcontext *ctx,
 424                 const SWvertex *v0,
 425                 const SWvertex *v1,
 426                 const SWvertex *v2)
 427 {
 428 #define DO_Z
 429 #define DO_FOG
 430 #define DO_RGBA
 431 #define DO_MULTITEX
 432 #include "s_aatritemp.h"
 433 }
 434
 435 static void
 436 spec_multitex_aa_tri(GLcontext *ctx,
 437                      const SWvertex *v0,
 438                      const SWvertex *v1,
 439                      const SWvertex *v2)
 440 {
 441 #define DO_Z
 442 #define DO_FOG
 443 #define DO_RGBA
 444 #define DO_MULTITEX
 445 #define DO_SPEC
 446 #include "s_aatritemp.h"
 447 }
 448
 449
 450 /*
 451  * Examine GL state and set swrast->Triangle to an
 452  * appropriate antialiased triangle rasterizer function.
 453  */
 454 void
 455 _mesa_set_aa_triangle_function(GLcontext *ctx)
 456 {
 457    ASSERT(ctx->Polygon.SmoothFlag);
 458
 459    if (ctx->Texture._EnabledUnits != 0) {
 460       if (ctx->_TriangleCaps & DD_SEPARATE_SPECULAR) {
 461          if (ctx->Texture._EnabledUnits > 1) {
 462             SWRAST_CONTEXT(ctx)->Triangle = spec_multitex_aa_tri;
 463          }
 464          else {
 465             SWRAST_CONTEXT(ctx)->Triangle = spec_tex_aa_tri;
 466          }
 467       }
 468       else {
 469          if (ctx->Texture._EnabledUnits > 1) {
 470             SWRAST_CONTEXT(ctx)->Triangle = multitex_aa_tri;
 471          }
 472          else {
 473             SWRAST_CONTEXT(ctx)->Triangle = tex_aa_tri;
 474          }
 475       }
 476    }
 477    else if (ctx->Visual.rgbMode) {
 478       SWRAST_CONTEXT(ctx)->Triangle = rgba_aa_tri;
 479    }
 480    else {
 481       SWRAST_CONTEXT(ctx)->Triangle = index_aa_tri;
 482    }
 483
 484    ASSERT(SWRAST_CONTEXT(ctx)->Triangle);
 485 }