reactos/dll/opengl/mesa/src/mesa/swrast/s_aatriangle.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 /*
  27  * Antialiased Triangle rasterizers
  28  */
  29
  30
  31 #include "main/glheader.h"
  32 #include "main/context.h"
  33 #include "main/colormac.h"
  34 #include "main/macros.h"
  35 #include "main/imports.h"
  36 #include "main/state.h"
  37 #include "s_aatriangle.h"
  38 #include "s_context.h"
  39 #include "s_fragprog.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 static inline GLfloat
 149 plane_dx(const GLfloat plane[4])
 150 {
 151    return -plane[0] / plane[2];
 152 }
 153
 154 static inline GLfloat
 155 plane_dy(const GLfloat plane[4])
 156 {
 157    return -plane[1] / plane[2];
 158 }
 159
 160
 161
 162 /*
 163  * Compute how much (area) of the given pixel is inside the triangle.
 164  * Vertices MUST be specified in counter-clockwise order.
 165  * Return:  coverage in [0, 1].
 166  */
 167 static GLfloat
 168 compute_coveragef(const GLfloat v0[3], const GLfloat v1[3],
 169                   const GLfloat v2[3], GLint winx, GLint winy)
 170 {
 171    /* Given a position [0,3]x[0,3] return the sub-pixel sample position.
 172     * Contributed by Ray Tice.
 173     *
 174     * Jitter sample positions -
 175     * - average should be .5 in x & y for each column
 176     * - each of the 16 rows and columns should be used once
 177     * - the rectangle formed by the first four points
 178     *   should contain the other points
 179     * - the distrubition should be fairly even in any given direction
 180     *
 181     * The pattern drawn below isn't optimal, but it's better than a regular
 182     * grid.  In the drawing, the center of each subpixel is surrounded by
 183     * four dots.  The "x" marks the jittered position relative to the
 184     * subpixel center.
 185     */
 186 #define POS(a, b) (0.5+a*4+b)/16
 187    static const GLfloat samples[16][2] = {
 188       /* start with the four corners */
 189       { POS(0, 2), POS(0, 0) },
 190       { POS(3, 3), POS(0, 2) },
 191       { POS(0, 0), POS(3, 1) },
 192       { POS(3, 1), POS(3, 3) },
 193       /* continue with interior samples */
 194       { POS(1, 1), POS(0, 1) },
 195       { POS(2, 0), POS(0, 3) },
 196       { POS(0, 3), POS(1, 3) },
 197       { POS(1, 2), POS(1, 0) },
 198       { POS(2, 3), POS(1, 2) },
 199       { POS(3, 2), POS(1, 1) },
 200       { POS(0, 1), POS(2, 2) },
 201       { POS(1, 0), POS(2, 1) },
 202       { POS(2, 1), POS(2, 3) },
 203       { POS(3, 0), POS(2, 0) },
 204       { POS(1, 3), POS(3, 0) },
 205       { POS(2, 2), POS(3, 2) }
 206    };
 207
 208    const GLfloat x = (GLfloat) winx;
 209    const GLfloat y = (GLfloat) winy;
 210    const GLfloat dx0 = v1[0] - v0[0];
 211    const GLfloat dy0 = v1[1] - v0[1];
 212    const GLfloat dx1 = v2[0] - v1[0];
 213    const GLfloat dy1 = v2[1] - v1[1];
 214    const GLfloat dx2 = v0[0] - v2[0];
 215    const GLfloat dy2 = v0[1] - v2[1];
 216    GLint stop = 4, i;
 217    GLfloat insideCount = 16.0F;
 218
 219    ASSERT(dx0 * dy1 - dx1 * dy0 >= 0.0); /* area >= 0.0 */
 220
 221    for (i = 0; i < stop; i++) {
 222       const GLfloat sx = x + samples[i][0];
 223       const GLfloat sy = y + samples[i][1];
 224       /* cross product determines if sample is inside or outside each edge */
 225       GLfloat cross = (dx0 * (sy - v0[1]) - dy0 * (sx - v0[0]));
 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 (cross == 0.0F)
 230          cross = dx0 + dy0;
 231       if (cross < 0.0F) {
 232          /* sample point is outside first edge */
 233          insideCount -= 1.0F;
 234          stop = 16;
 235       }
 236       else {
 237          /* sample point is inside first edge */
 238          cross = (dx1 * (sy - v1[1]) - dy1 * (sx - v1[0]));
 239          if (cross == 0.0F)
 240             cross = dx1 + dy1;
 241          if (cross < 0.0F) {
 242             /* sample point is outside second edge */
 243             insideCount -= 1.0F;
 244             stop = 16;
 245          }
 246          else {
 247             /* sample point is inside first and second edges */
 248             cross = (dx2 * (sy - v2[1]) -  dy2 * (sx - v2[0]));
 249             if (cross == 0.0F)
 250                cross = dx2 + dy2;
 251             if (cross < 0.0F) {
 252                /* sample point is outside third edge */
 253                insideCount -= 1.0F;
 254                stop = 16;
 255             }
 256          }
 257       }
 258    }
 259    if (stop == 4)
 260       return 1.0F;
 261    else
 262       return insideCount * (1.0F / 16.0F);
 263 }
 264
 265
 266
 267 static void
 268 rgba_aa_tri(struct gl_context *ctx,
 269             const SWvertex *v0,
 270             const SWvertex *v1,
 271             const SWvertex *v2)
 272 {
 273 #define DO_Z
 274 #include "s_aatritemp.h"
 275 }
 276
 277
 278 static void
 279 general_aa_tri(struct gl_context *ctx,
 280                const SWvertex *v0,
 281                const SWvertex *v1,
 282                const SWvertex *v2)
 283 {
 284 #define DO_Z
 285 #define DO_ATTRIBS
 286 #include "s_aatritemp.h"
 287 }
 288
 289
 290
 291 /*
 292  * Examine GL state and set swrast->Triangle to an
 293  * appropriate antialiased triangle rasterizer function.
 294  */
 295 void
 296 _swrast_set_aa_triangle_function(struct gl_context *ctx)
 297 {
 298    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 299
 300    ASSERT(ctx->Polygon.SmoothFlag);
 301
 302    if (ctx->Texture._EnabledCoordUnits != 0
 303        || _swrast_use_fragment_program(ctx)
 304        || swrast->_FogEnabled
 305        || _mesa_need_secondary_color(ctx)) {
 306       SWRAST_CONTEXT(ctx)->Triangle = general_aa_tri;
 307    }
 308    else {
 309       SWRAST_CONTEXT(ctx)->Triangle = rgba_aa_tri;
 310    }
 311
 312    ASSERT(SWRAST_CONTEXT(ctx)->Triangle);
 313 }