summaryrefslogtreecommitdiffstats
path: root/src/mesa/swrast/s_aaline.c
blob: f0a8a8d06a744af43ff42dbd13da77d0c1fd2a99 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
/* $Id: s_aaline.c,v 1.6 2001/03/12 00:48:41 gareth Exp $ */

/*
 * Mesa 3-D graphics library
 * Version:  3.5
 *
 * Copyright (C) 1999-2001  Brian Paul   All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */


#include "glheader.h"
#include "swrast/s_aaline.h"
#include "swrast/s_pb.h"
#include "swrast/s_context.h"
#include "swrast/swrast.h"
#include "mtypes.h"
#include "mmath.h"


#define SUB_PIXEL 4


/*
 * Info about the AA line we're rendering
 */
struct LineInfo
{
   GLfloat x0, y0;        /* start */
   GLfloat x1, y1;        /* end */
   GLfloat dx, dy;        /* direction vector */
   GLfloat len;           /* length */
   GLfloat halfWidth;     /* half of line width */
   GLfloat xAdj, yAdj;    /* X and Y adjustment for quad corners around line */
   /* for coverage computation */
   GLfloat qx0, qy0;      /* quad vertices */
   GLfloat qx1, qy1;
   GLfloat qx2, qy2;
   GLfloat qx3, qy3;
   GLfloat ex0, ey0;      /* quad edge vectors */
   GLfloat ex1, ey1;
   GLfloat ex2, ey2;
   GLfloat ex3, ey3;

   /* DO_Z */
   GLfloat zPlane[4];
   /* DO_FOG */
   GLfloat fPlane[4];
   /* DO_RGBA */
   GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];
   /* DO_INDEX */
   GLfloat iPlane[4];
   /* DO_SPEC */
   GLfloat srPlane[4], sgPlane[4], sbPlane[4];
   /* DO_TEX or DO_MULTITEX */
   GLfloat sPlane[MAX_TEXTURE_UNITS][4];
   GLfloat tPlane[MAX_TEXTURE_UNITS][4];
   GLfloat uPlane[MAX_TEXTURE_UNITS][4];
   GLfloat vPlane[MAX_TEXTURE_UNITS][4];
   GLfloat lambda[MAX_TEXTURE_UNITS];
   GLfloat texWidth[MAX_TEXTURE_UNITS], texHeight[MAX_TEXTURE_UNITS];
};



/*
 * Compute the equation of a plane used to interpolate line fragment data
 * such as color, Z, texture coords, etc.
 * Input: (x0, y0) and (x1,y1) are the endpoints of the line.
 *        z0, and z1 are the end point values to interpolate.
 * Output:  plane - the plane equation.
 *
 * Note: we don't really have enough parameters to specify a plane.
 * We take the endpoints of the line and compute a plane such that
 * the cross product of the line vector and the plane normal is
 * parallel to the projection plane.
 */
static void
compute_plane(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
              GLfloat z0, GLfloat z1, GLfloat plane[4])
{
#if 0
   /* original */
   const GLfloat px = x1 - x0;
   const GLfloat py = y1 - y0;
   const GLfloat pz = z1 - z0;
   const GLfloat qx = -py;
   const GLfloat qy = px;
   const GLfloat qz = 0;
   const GLfloat a = py * qz - pz * qy;
   const GLfloat b = pz * qx - px * qz;
   const GLfloat c = px * qy - py * qx;
   const GLfloat d = -(a * x0 + b * y0 + c * z0);
   plane[0] = a;
   plane[1] = b;
   plane[2] = c;
   plane[3] = d;
#else
   /* simplified */
   const GLfloat px = x1 - x0;
   const GLfloat py = y1 - y0;
   const GLfloat pz = z0 - z1;
   const GLfloat a = pz * px;
   const GLfloat b = pz * py;
   const GLfloat c = px * px + py * py;
   const GLfloat d = -(a * x0 + b * y0 + c * z0);
   plane[0] = a;
   plane[1] = b;
   plane[2] = c;
   plane[3] = d;
#endif
}


static INLINE void
constant_plane(GLfloat value, GLfloat plane[4])
{
   plane[0] = 0.0;
   plane[1] = 0.0;
   plane[2] = -1.0;
   plane[3] = value;
}


static INLINE GLfloat
solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
{
   GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
   return z;
}

#define SOLVE_PLANE(X, Y, PLANE) \
   ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])


/*
 * Return 1 / solve_plane().
 */
static INLINE GLfloat
solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
{
   GLfloat z = -plane[2] / (plane[3] + plane[0] * x + plane[1] * y);
   return z;
}


/*
 * Solve plane and return clamped GLchan value.
 */
static INLINE GLchan
solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
{
   GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2] + 0.5F;
   if (z < 0.0F)
      return 0;
   else if (z > CHAN_MAXF)
      return (GLchan) CHAN_MAXF;
   return (GLchan) (GLint) z;
}


/*
 * Compute mipmap level of detail.
 */
static INLINE GLfloat
compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
               GLfloat invQ, GLfloat width, GLfloat height)
{
   GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width;
   GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width;
   GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height;
   GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height;
   GLfloat r1 = dudx * dudx + dudy * dudy;
   GLfloat r2 = dvdx * dvdx + dvdy * dvdy;
   GLfloat rho2 = r1 + r2;
   /* return log base 2 of rho */
   return log(rho2) * 1.442695 * 0.5;       /* 1.442695 = 1/log(2) */
}




/*
 * Fill in the samples[] array with the (x,y) subpixel positions of
 * xSamples * ySamples sample positions.
 * Note that the four corner samples are put into the first four
 * positions of the array.  This allows us to optimize for the common
 * case of all samples being inside the polygon.
 */
static void
make_sample_table(GLint xSamples, GLint ySamples, GLfloat samples[][2])
{
   const GLfloat dx = 1.0F / (GLfloat) xSamples;
   const GLfloat dy = 1.0F / (GLfloat) ySamples;
   GLint x, y;
   GLint i;

   i = 4;
   for (x = 0; x < xSamples; x++) {
      for (y = 0; y < ySamples; y++) {
         GLint j;
         if (x == 0 && y == 0) {
            /* lower left */
            j = 0;
         }
         else if (x == xSamples - 1 && y == 0) {
            /* lower right */
            j = 1;
         }
         else if (x == 0 && y == ySamples - 1) {
            /* upper left */
            j = 2;
         }
         else if (x == xSamples - 1 && y == ySamples - 1) {
            /* upper right */
            j = 3;
         }
         else {
            j = i++;
         }
         samples[j][0] = x * dx;
         samples[j][1] = y * dy;
      }
   }
}



/*
 * Compute how much of the given pixel's area is inside the rectangle
 * defined by vertices v0, v1, v2, v3.
 * Vertices MUST be specified in counter-clockwise order.
 * Return:  coverage in [0, 1].
 */
static GLfloat
compute_coveragef(const struct LineInfo *info,
                  GLint winx, GLint winy)
{
   static GLfloat samples[SUB_PIXEL * SUB_PIXEL][2];
   static GLboolean haveSamples = GL_FALSE;
   const GLfloat x = (GLfloat) winx;
   const GLfloat y = (GLfloat) winy;
   GLint stop = 4, i;
   GLfloat insideCount = SUB_PIXEL * SUB_PIXEL;

   if (!haveSamples) {
      make_sample_table(SUB_PIXEL, SUB_PIXEL, samples);
      haveSamples = GL_TRUE;
   }

#if 0 /*DEBUG*/
   {
      const GLfloat area = dx0 * dy1 - dx1 * dy0;
      assert(area >= 0.0);
   }
#endif

   for (i = 0; i < stop; i++) {
      const GLfloat sx = x + samples[i][0];
      const GLfloat sy = y + samples[i][1];
      const GLfloat fx0 = sx - info->qx0;
      const GLfloat fy0 = sy - info->qy0;
      const GLfloat fx1 = sx - info->qx1;
      const GLfloat fy1 = sy - info->qy1;
      const GLfloat fx2 = sx - info->qx2;
      const GLfloat fy2 = sy - info->qy2;
      const GLfloat fx3 = sx - info->qx3;
      const GLfloat fy3 = sy - info->qy3;
      /* cross product determines if sample is inside or outside each edge */
      GLfloat cross0 = (info->ex0 * fy0 - info->ey0 * fx0);
      GLfloat cross1 = (info->ex1 * fy1 - info->ey1 * fx1);
      GLfloat cross2 = (info->ex2 * fy2 - info->ey2 * fx2);
      GLfloat cross3 = (info->ex3 * fy3 - info->ey3 * fx3);
      /* Check if the sample is exactly on an edge.  If so, let cross be a
       * positive or negative value depending on the direction of the edge.
       */
      if (cross0 == 0.0F)
         cross0 = info->ex0 + info->ey0;
      if (cross1 == 0.0F)
         cross1 = info->ex1 + info->ey1;
      if (cross2 == 0.0F)
         cross2 = info->ex2 + info->ey2;
      if (cross3 == 0.0F)
         cross3 = info->ex3 + info->ey3;
      if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F || cross3 < 0.0F) {
         /* point is outside quadrilateral */
         insideCount -= 1.0F;
         stop = SUB_PIXEL * SUB_PIXEL;
      }
   }
   if (stop == 4)
      return 1.0F;
   else
      return insideCount * (1.0F / (SUB_PIXEL * SUB_PIXEL));
}



typedef void (*plot_func)(GLcontext *ctx, const struct LineInfo *line,
                          struct pixel_buffer *pb, int ix, int iy);


/*
 * Draw an AA line segment (called many times per line when stippling)
 */
static void
segment(GLcontext *ctx,
        struct LineInfo *line,
        plot_func plot,
        struct pixel_buffer *pb,
        GLfloat t0, GLfloat t1)
{
   const GLfloat absDx = (line->dx < 0.0F) ? -line->dx : line->dx;
   const GLfloat absDy = (line->dy < 0.0F) ? -line->dy : line->dy;
   /* compute the actual segment's endpoints */
   const GLfloat x0 = line->x0 + t0 * line->dx;
   const GLfloat y0 = line->y0 + t0 * line->dy;
   const GLfloat x1 = line->x0 + t1 * line->dx;
   const GLfloat y1 = line->y0 + t1 * line->dy;

   /* compute vertices of the line-aligned quadrilateral */
   line->qx0 = x0 - line->yAdj;
   line->qy0 = y0 + line->xAdj;
   line->qx1 = x0 + line->yAdj;
   line->qy1 = y0 - line->xAdj;
   line->qx2 = x1 + line->yAdj;
   line->qy2 = y1 - line->xAdj;
   line->qx3 = x1 - line->yAdj;
   line->qy3 = y1 + line->xAdj;
   /* compute the quad's edge vectors (for coverage calc) */
   line->ex0 = line->qx1 - line->qx0;
   line->ey0 = line->qy1 - line->qy0;
   line->ex1 = line->qx2 - line->qx1;
   line->ey1 = line->qy2 - line->qy1;
   line->ex2 = line->qx3 - line->qx2;
   line->ey2 = line->qy3 - line->qy2;
   line->ex3 = line->qx0 - line->qx3;
   line->ey3 = line->qy0 - line->qy3;

   if (absDx > absDy) {
      /* X-major line */
      GLfloat dydx = line->dy / line->dx;
      GLfloat xLeft, xRight, yBot, yTop;
      GLint ix, ixRight;
      if (x0 < x1) {
         xLeft = x0 - line->halfWidth;
         xRight = x1 + line->halfWidth;
         if (line->dy >= 0.0) {
            yBot = y0 - 3.0 * line->halfWidth;
            yTop = y0 + line->halfWidth;
         }
         else {
            yBot = y0 - line->halfWidth;
            yTop = y0 + 3.0 * line->halfWidth;
         }
      }
      else {
         xLeft = x1 - line->halfWidth;
         xRight = x0 + line->halfWidth;
         if (line->dy <= 0.0) {
            yBot = y1 - 3.0 * line->halfWidth;
            yTop = y1 + line->halfWidth;
         }
         else {
            yBot = y1 - line->halfWidth;
            yTop = y1 + 3.0 * line->halfWidth;
         }
      }

      /* scan along the line, left-to-right */
      ixRight = (GLint) (xRight + 1.0F);

      /*printf("avg span height: %g\n", yTop - yBot);*/
      for (ix = (GLint) xLeft; ix < ixRight; ix++) {
         const GLint iyBot = (GLint) yBot;
         const GLint iyTop = (GLint) (yTop + 1.0F);
         GLint iy;
         /* scan across the line, bottom-to-top */
         for (iy = iyBot; iy < iyTop; iy++) {
            (*plot)(ctx, line, pb, ix, iy);
         }
         yBot += dydx;
         yTop += dydx;
      }
   }
   else {
      /* Y-major line */
      GLfloat dxdy = line->dx / line->dy;
      GLfloat yBot, yTop, xLeft, xRight;
      GLint iy, iyTop;
      if (y0 < y1) {
         yBot = y0 - line->halfWidth;
         yTop = y1 + line->halfWidth;
         if (line->dx >= 0.0) {
            xLeft = x0 - 3.0 * line->halfWidth;
            xRight = x0 + line->halfWidth;
         }
         else {
            xLeft = x0 - line->halfWidth;
            xRight = x0 + 3.0 * line->halfWidth;
         }
      }
      else {
         yBot = y1 - line->halfWidth;
         yTop = y0 + line->halfWidth;
         if (line->dx <= 0.0) {
            xLeft = x1 - 3.0 * line->halfWidth;
            xRight = x1 + line->halfWidth;
         }
         else {
            xLeft = x1 - line->halfWidth;
            xRight = x1 + 3.0 * line->halfWidth;
         }
      }

      /* scan along the line, bottom-to-top */
      iyTop = (GLint) (yTop + 1.0F);

      /*printf("avg span width: %g\n", xRight - xLeft);*/
      for (iy = (GLint) yBot; iy < iyTop; iy++) {
         const GLint ixLeft = (GLint) xLeft;
         const GLint ixRight = (GLint) (xRight + 1.0F);
         GLint ix;
         /* scan across the line, left-to-right */
         for (ix = ixLeft; ix < ixRight; ix++) {
            (*plot)(ctx, line, pb, ix, iy);
         }
         xLeft += dxdy;
         xRight += dxdy;
      }
   }
}


#define NAME(x) aa_ci_##x
#define DO_Z
#define DO_FOG
#define DO_INDEX
#include "s_aalinetemp.h"


#define NAME(x) aa_rgba_##x
#define DO_Z
#define DO_FOG
#define DO_RGBA
#include "s_aalinetemp.h"


#define NAME(x)  aa_tex_rgba_##x
#define DO_Z
#define DO_FOG
#define DO_RGBA
#define DO_TEX
#include "s_aalinetemp.h"


#define NAME(x)  aa_multitex_rgba_##x
#define DO_Z
#define DO_RGBA
#define DO_MULTITEX
#define DO_SPEC
#include "s_aalinetemp.h"



void
_swrast_choose_aa_line_function(GLcontext *ctx)
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   ASSERT(ctx->Line.SmoothFlag);

   if (ctx->Visual.rgbMode) {
      /* RGBA */
      if (ctx->Texture._ReallyEnabled) {
         if (swrast->_MultiTextureEnabled
             || ctx->Light.Model.ColorControl==GL_SEPARATE_SPECULAR_COLOR
             || ctx->Fog.ColorSumEnabled)
            /* Multitextured! */
            swrast->Line = aa_multitex_rgba_line;
         else
            swrast->Line = aa_tex_rgba_line;
      }
      else {
         swrast->Line = aa_rgba_line;
      }
   }
   else {
      /* Color Index */
      swrast->Line = aa_ci_line;
   }
}