summaryrefslogtreecommitdiffstats
blob: fa6338aa4972317282c54e4f161e3d5f7ec648d2 (plain) (blame)
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
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
/* libs/pixelflinger/trap.cpp
**
** Copyright 2006, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
**     http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/

#define LOG_TAG "pixelflinger-trap"

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

#include <android/log.h>
#include <cutils/memory.h>

#include "trap.h"
#include "picker.h"

namespace android {

// ----------------------------------------------------------------------------

// enable to see triangles edges
#define DEBUG_TRANGLES  0

// ----------------------------------------------------------------------------

static void pointx_validate(void *con, const GGLcoord* c, GGLcoord r);
static void pointx(void *con, const GGLcoord* c, GGLcoord r);
static void aa_pointx(void *con, const GGLcoord* c, GGLcoord r);
static void aa_nice_pointx(void *con, const GGLcoord* c, GGLcoord r);

static void linex_validate(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w);
static void linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w);
static void aa_linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w);

static void recti_validate(void* c, GGLint l, GGLint t, GGLint r, GGLint b); 
static void recti(void* c, GGLint l, GGLint t, GGLint r, GGLint b); 

static void trianglex_validate(void*,
        const GGLcoord*, const GGLcoord*, const GGLcoord*);
static void trianglex_small(void*,
        const GGLcoord*, const GGLcoord*, const GGLcoord*);
static void trianglex_big(void*,
        const GGLcoord*, const GGLcoord*, const GGLcoord*);
static void aa_trianglex(void*,
        const GGLcoord*, const GGLcoord*, const GGLcoord*);
static void trianglex_debug(void* con,
        const GGLcoord*, const GGLcoord*, const GGLcoord*);

static void aapolyx(void* con,
        const GGLcoord* pts, int count);

static inline int min(int a, int b) CONST;
static inline int max(int a, int b) CONST;
static inline int min(int a, int b, int c) CONST;
static inline int max(int a, int b, int c) CONST;

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Tools
#endif

inline int min(int a, int b) {
    return a<b ? a : b;
}
inline int max(int a, int b) {
    return a<b ? b : a;
}
inline int min(int a, int b, int c) {
    return min(a,min(b,c));
}
inline int max(int a, int b, int c) {
    return max(a,max(b,c));
}

template <typename T>
static inline void swap(T& a, T& b) {
    T t(a);
    a = b;
    b = t;
}

static void
triangle_dump_points( const GGLcoord*  v0,
                      const GGLcoord*  v1,
                      const GGLcoord*  v2 )
{
    float tri = 1.0f / TRI_ONE;
    ALOGD("  P0=(%.3f, %.3f)  [%08x, %08x]\n"
          "  P1=(%.3f, %.3f)  [%08x, %08x]\n"
          "  P2=(%.3f, %.3f)  [%08x, %08x]\n",
          v0[0]*tri, v0[1]*tri, v0[0], v0[1],
          v1[0]*tri, v1[1]*tri, v1[0], v1[1],
          v2[0]*tri, v2[1]*tri, v2[0], v2[1] );
}

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Misc
#endif

void ggl_init_trap(context_t* c)
{
    ggl_state_changed(c, GGL_PIXEL_PIPELINE_STATE|GGL_TMU_STATE|GGL_CB_STATE);
}

void ggl_state_changed(context_t* c, int flags)
{
    if (ggl_likely(!c->dirty)) {
        c->procs.pointx     = pointx_validate;
        c->procs.linex      = linex_validate;
        c->procs.recti      = recti_validate;
        c->procs.trianglex  = trianglex_validate;
    }
    c->dirty |= uint32_t(flags);
}

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Point
#endif

void pointx_validate(void *con, const GGLcoord* v, GGLcoord rad)
{
    GGL_CONTEXT(c, con);
    ggl_pick(c);
    if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
        if (c->state.enables & GGL_ENABLE_POINT_AA_NICE) {
            c->procs.pointx = aa_nice_pointx;
        } else {
            c->procs.pointx = aa_pointx;
        }
    } else {
        c->procs.pointx = pointx;
    }
    c->procs.pointx(con, v, rad);
}

void pointx(void *con, const GGLcoord* v, GGLcoord rad)
{
    GGL_CONTEXT(c, con);
    GGLcoord halfSize = TRI_ROUND(rad) >> 1;
    if (halfSize == 0)
        halfSize = TRI_HALF;
    GGLcoord xc = v[0]; 
    GGLcoord yc = v[1];
    if (halfSize & TRI_HALF) { // size odd
        xc = TRI_FLOOR(xc) + TRI_HALF;
        yc = TRI_FLOOR(yc) + TRI_HALF;
    } else { // size even
        xc = TRI_ROUND(xc);
        yc = TRI_ROUND(yc);
    }
    GGLint l = (xc - halfSize) >> TRI_FRACTION_BITS;
    GGLint t = (yc - halfSize) >> TRI_FRACTION_BITS;
    GGLint r = (xc + halfSize) >> TRI_FRACTION_BITS;
    GGLint b = (yc + halfSize) >> TRI_FRACTION_BITS;
    recti(c, l, t, r, b);
}

// This way of computing the coverage factor, is more accurate and gives
// better results for small circles, but it is also a lot slower.
// Here we use super-sampling.
static int32_t coverageNice(GGLcoord x, GGLcoord y, 
        GGLcoord rmin, GGLcoord rmax, GGLcoord rr)
{
    const GGLcoord d2 = x*x + y*y;
    if (d2 >= rmax) return 0;
    if (d2 < rmin)  return 0x7FFF;

    const int kSamples              =  4;
    const int kInc                  =  4;    // 1/4 = 0.25
    const int kCoverageUnit         =  1;    // 1/(4^2) = 0.0625
    const GGLcoord kCoordOffset     = -6;    // -0.375

    int hits = 0;
    int x_sample = x + kCoordOffset;
    for (int i=0 ; i<kSamples ; i++, x_sample += kInc) {
        const int xval = rr - (x_sample * x_sample);
        int y_sample = y + kCoordOffset;
        for (int j=0 ; j<kSamples ; j++, y_sample += kInc) {
            if (xval - (y_sample * y_sample) > 0)
                hits += kCoverageUnit;
        }
    }
    return min(0x7FFF, hits << (15 - kSamples));
}


void aa_nice_pointx(void *con, const GGLcoord* v, GGLcoord size)
{
    GGL_CONTEXT(c, con);

    GGLcoord rad = ((size + 1)>>1);
    GGLint l = (v[0] - rad) >> TRI_FRACTION_BITS;
    GGLint t = (v[1] - rad) >> TRI_FRACTION_BITS;
    GGLint r = (v[0] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
    GGLint b = (v[1] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
    GGLcoord xstart = TRI_FROM_INT(l) - v[0] + TRI_HALF; 
    GGLcoord ystart = TRI_FROM_INT(t) - v[1] + TRI_HALF; 

    // scissor...
    if (l < GGLint(c->state.scissor.left)) {
        xstart += TRI_FROM_INT(c->state.scissor.left-l);
        l = GGLint(c->state.scissor.left);
    }
    if (t < GGLint(c->state.scissor.top)) {
        ystart += TRI_FROM_INT(c->state.scissor.top-t);
        t = GGLint(c->state.scissor.top);
    }
    if (r > GGLint(c->state.scissor.right)) {
        r = GGLint(c->state.scissor.right);
    }
    if (b > GGLint(c->state.scissor.bottom)) {
        b = GGLint(c->state.scissor.bottom);
    }

    int xc = r - l;
    int yc = b - t;
    if (xc>0 && yc>0) {
        int16_t* covPtr = c->state.buffers.coverage;
        const int32_t sqr2Over2 = 0xC; // rounded up
        GGLcoord rr = rad*rad;
        GGLcoord rmin = (rad - sqr2Over2)*(rad - sqr2Over2);
        GGLcoord rmax = (rad + sqr2Over2)*(rad + sqr2Over2);
        GGLcoord y = ystart;
        c->iterators.xl = l;
        c->iterators.xr = r;
        c->init_y(c, t);
        do {
            // compute coverage factors for each pixel
            GGLcoord x = xstart;
            for (int i=l ; i<r ; i++) {
                covPtr[i] = coverageNice(x, y, rmin, rmax, rr);
                x += TRI_ONE;
            }
            y += TRI_ONE;
            c->scanline(c);
            c->step_y(c);
        } while (--yc);
    }
}

// This is a cheap way of computing the coverage factor for a circle.
// We just lerp between the circles of radii r-sqrt(2)/2 and r+sqrt(2)/2
static inline int32_t coverageFast(GGLcoord x, GGLcoord y,
        GGLcoord rmin, GGLcoord rmax, GGLcoord scale)
{
    const GGLcoord d2 = x*x + y*y;
    if (d2 >= rmax) return 0;
    if (d2 < rmin)  return 0x7FFF;
    return 0x7FFF - (d2-rmin)*scale;
}

void aa_pointx(void *con, const GGLcoord* v, GGLcoord size)
{
    GGL_CONTEXT(c, con);

    GGLcoord rad = ((size + 1)>>1);
    GGLint l = (v[0] - rad) >> TRI_FRACTION_BITS;
    GGLint t = (v[1] - rad) >> TRI_FRACTION_BITS;
    GGLint r = (v[0] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
    GGLint b = (v[1] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
    GGLcoord xstart = TRI_FROM_INT(l) - v[0] + TRI_HALF; 
    GGLcoord ystart = TRI_FROM_INT(t) - v[1] + TRI_HALF; 

    // scissor...
    if (l < GGLint(c->state.scissor.left)) {
        xstart += TRI_FROM_INT(c->state.scissor.left-l);
        l = GGLint(c->state.scissor.left);
    }
    if (t < GGLint(c->state.scissor.top)) {
        ystart += TRI_FROM_INT(c->state.scissor.top-t);
        t = GGLint(c->state.scissor.top);
    }
    if (r > GGLint(c->state.scissor.right)) {
        r = GGLint(c->state.scissor.right);
    }
    if (b > GGLint(c->state.scissor.bottom)) {
        b = GGLint(c->state.scissor.bottom);
    }

    int xc = r - l;
    int yc = b - t;
    if (xc>0 && yc>0) {
        int16_t* covPtr = c->state.buffers.coverage;
        rad <<= 4;
        const int32_t sqr2Over2 = 0xB5;    // fixed-point 24.8
        GGLcoord rmin = rad - sqr2Over2;
        GGLcoord rmax = rad + sqr2Over2;
        GGLcoord scale;
        rmin *= rmin;
        rmax *= rmax;
        scale = 0x800000 / (rmax - rmin);
        rmin >>= 8;
        rmax >>= 8;

        GGLcoord y = ystart;
        c->iterators.xl = l;
        c->iterators.xr = r;
        c->init_y(c, t);

        do {
            // compute coverage factors for each pixel
            GGLcoord x = xstart;
            for (int i=l ; i<r ; i++) {
                covPtr[i] = coverageFast(x, y, rmin, rmax, scale);
                x += TRI_ONE;
            }
            y += TRI_ONE;
            c->scanline(c);
            c->step_y(c);
        } while (--yc);
    }
}

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Line
#endif

void linex_validate(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w)
{
    GGL_CONTEXT(c, con);
    ggl_pick(c);
    if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
        c->procs.linex = aa_linex;
    } else {
        c->procs.linex = linex;
    }
    c->procs.linex(con, v0, v1, w);
}

static void linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord width)
{
    GGL_CONTEXT(c, con);
    GGLcoord v[4][2];
    v[0][0] = v0[0];    v[0][1] = v0[1];
    v[1][0] = v1[0];    v[1][1] = v1[1];
    v0 = v[0];
    v1 = v[1];
    const GGLcoord dx = abs(v0[0] - v1[0]);
    const GGLcoord dy = abs(v0[1] - v1[1]);
    GGLcoord nx, ny;
    nx = ny = 0;

    GGLcoord halfWidth = TRI_ROUND(width) >> 1;
    if (halfWidth == 0)
        halfWidth = TRI_HALF;

    ((dx > dy) ? ny : nx) = halfWidth;
    v[2][0] = v1[0];    v[2][1] = v1[1];
    v[3][0] = v0[0];    v[3][1] = v0[1];
    v[0][0] += nx;      v[0][1] += ny;
    v[1][0] += nx;      v[1][1] += ny;
    v[2][0] -= nx;      v[2][1] -= ny;
    v[3][0] -= nx;      v[3][1] -= ny;
    trianglex_big(con, v[0], v[1], v[2]);
    trianglex_big(con, v[0], v[2], v[3]);
}

static void aa_linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord width)
{
    GGL_CONTEXT(c, con);
    GGLcoord v[4][2];
    v[0][0] = v0[0];    v[0][1] = v0[1];
    v[1][0] = v1[0];    v[1][1] = v1[1];
    v0 = v[0];
    v1 = v[1];
    
    const GGLcoord dx = v0[0] - v1[0];
    const GGLcoord dy = v0[1] - v1[1];
    GGLcoord nx = -dy;
    GGLcoord ny =  dx;

    // generally, this will be well below 1.0
    const GGLfixed norm = gglMulx(width, gglSqrtRecipx(nx*nx+ny*ny), 4);
    nx = gglMulx(nx, norm, 21);
    ny = gglMulx(ny, norm, 21);
    
    v[2][0] = v1[0];    v[2][1] = v1[1];
    v[3][0] = v0[0];    v[3][1] = v0[1];
    v[0][0] += nx;      v[0][1] += ny;
    v[1][0] += nx;      v[1][1] += ny;
    v[2][0] -= nx;      v[2][1] -= ny;
    v[3][0] -= nx;      v[3][1] -= ny;
    aapolyx(con, v[0], 4);        
}


// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Rect
#endif

void recti_validate(void *con, GGLint l, GGLint t, GGLint r, GGLint b)
{
    GGL_CONTEXT(c, con);
    ggl_pick(c);
    c->procs.recti = recti;
    c->procs.recti(con, l, t, r, b);
}

void recti(void* con, GGLint l, GGLint t, GGLint r, GGLint b)
{
    GGL_CONTEXT(c, con);

    // scissor...
    if (l < GGLint(c->state.scissor.left))
        l = GGLint(c->state.scissor.left);
    if (t < GGLint(c->state.scissor.top))
        t = GGLint(c->state.scissor.top);
    if (r > GGLint(c->state.scissor.right))
        r = GGLint(c->state.scissor.right);
    if (b > GGLint(c->state.scissor.bottom))
        b = GGLint(c->state.scissor.bottom);

    int xc = r - l;
    int yc = b - t;
    if (xc>0 && yc>0) {
        c->iterators.xl = l;
        c->iterators.xr = r;
        c->init_y(c, t);
        c->rect(c, yc);
    }
}

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Triangle / Debugging
#endif

static void scanline_set(context_t* c)
{
    int32_t x = c->iterators.xl;
    size_t ct = c->iterators.xr - x;
    int32_t y = c->iterators.y;
    surface_t* cb = &(c->state.buffers.color);
    const GGLFormat* fp = &(c->formats[cb->format]);
    uint8_t* dst = reinterpret_cast<uint8_t*>(cb->data) +
                            (x + (cb->stride * y)) * fp->size;
    const size_t size = ct * fp->size;
    memset(dst, 0xFF, size);
}

static void trianglex_debug(void* con,
        const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
{
    GGL_CONTEXT(c, con);
    if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
        aa_trianglex(con,v0,v1,v2);
    } else {
        trianglex_big(con,v0,v1,v2);
    }
	void (*save_scanline)(context_t*)  = c->scanline;
    c->scanline = scanline_set;
    linex(con, v0, v1, TRI_ONE);
    linex(con, v1, v2, TRI_ONE);
    linex(con, v2, v0, TRI_ONE);
    c->scanline = save_scanline;
}

static void trianglex_xor(void* con,
        const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
{
    trianglex_big(con,v0,v1,v2);
    trianglex_small(con,v0,v1,v2);
}

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Triangle
#endif

void trianglex_validate(void *con,
        const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
{
    GGL_CONTEXT(c, con);
    ggl_pick(c);
    if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
        c->procs.trianglex = DEBUG_TRANGLES ? trianglex_debug : aa_trianglex;
    } else {
        c->procs.trianglex = DEBUG_TRANGLES ? trianglex_debug : trianglex_big;
    }
    c->procs.trianglex(con, v0, v1, v2);
}

// ----------------------------------------------------------------------------

void trianglex_small(void* con,
        const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
{
    GGL_CONTEXT(c, con);

    // vertices are in 28.4 fixed point, which allows
    // us to use 32 bits multiplies below.
    int32_t x0 = v0[0];
    int32_t y0 = v0[1];
    int32_t x1 = v1[0];
    int32_t y1 = v1[1];
    int32_t x2 = v2[0];
    int32_t y2 = v2[1];

    int32_t dx01 = x0 - x1;
    int32_t dy20 = y2 - y0;
    int32_t dy01 = y0 - y1;
    int32_t dx20 = x2 - x0;

    // The code below works only with CCW triangles
    // so if we get a CW triangle, we need to swap two of its vertices
    if (dx01*dy20 < dy01*dx20) {
        swap(x0, x1);
        swap(y0, y1);
        dx01 = x0 - x1;
        dy01 = y0 - y1;
        dx20 = x2 - x0;
        dy20 = y2 - y0;
    }
    int32_t dx12 = x1 - x2;
    int32_t dy12 = y1 - y2;

    // bounding box & scissor
    const int32_t bminx = TRI_FLOOR(min(x0, x1, x2)) >> TRI_FRACTION_BITS;
    const int32_t bminy = TRI_FLOOR(min(y0, y1, y2)) >> TRI_FRACTION_BITS;
    const int32_t bmaxx = TRI_CEIL( max(x0, x1, x2)) >> TRI_FRACTION_BITS;
    const int32_t bmaxy = TRI_CEIL( max(y0, y1, y2)) >> TRI_FRACTION_BITS;
    const int32_t minx = max(bminx, c->state.scissor.left);
    const int32_t miny = max(bminy, c->state.scissor.top);
    const int32_t maxx = min(bmaxx, c->state.scissor.right);
    const int32_t maxy = min(bmaxy, c->state.scissor.bottom);
    if ((minx >= maxx) || (miny >= maxy))
        return; // too small or clipped out...

    // step equations to the bounding box and snap to pixel center
    const int32_t my = (miny << TRI_FRACTION_BITS) + TRI_HALF;
    const int32_t mx = (minx << TRI_FRACTION_BITS) + TRI_HALF;
    int32_t ey0 = dy01 * (x0 - mx) - dx01 * (y0 - my);
    int32_t ey1 = dy12 * (x1 - mx) - dx12 * (y1 - my);
    int32_t ey2 = dy20 * (x2 - mx) - dx20 * (y2 - my);

    // right-exclusive fill rule, to avoid rare cases
    // of over drawing
    if (dy01<0 || (dy01 == 0 && dx01>0)) ey0++;
    if (dy12<0 || (dy12 == 0 && dx12>0)) ey1++;
    if (dy20<0 || (dy20 == 0 && dx20>0)) ey2++;
    
    c->init_y(c, miny);
    for (int32_t y = miny; y < maxy; y++) {
        int32_t ex0 = ey0;
        int32_t ex1 = ey1;
        int32_t ex2 = ey2;    
        int32_t xl, xr;
        for (xl=minx ; xl<maxx ; xl++) {
            if (ex0>0 && ex1>0 && ex2>0)
                break; // all strictly positive
            ex0 -= dy01 << TRI_FRACTION_BITS;
            ex1 -= dy12 << TRI_FRACTION_BITS;
            ex2 -= dy20 << TRI_FRACTION_BITS;
        }
        xr = xl;
        for ( ; xr<maxx ; xr++) {
            if (!(ex0>0 && ex1>0 && ex2>0))
                break; // not all strictly positive
            ex0 -= dy01 << TRI_FRACTION_BITS;
            ex1 -= dy12 << TRI_FRACTION_BITS;
            ex2 -= dy20 << TRI_FRACTION_BITS;
        }

        if (xl < xr) {
            c->iterators.xl = xl;
            c->iterators.xr = xr;
            c->scanline(c);
        }
        c->step_y(c);

        ey0 += dx01 << TRI_FRACTION_BITS;
        ey1 += dx12 << TRI_FRACTION_BITS;
        ey2 += dx20 << TRI_FRACTION_BITS;
    }
}

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#endif

// the following routine fills a triangle via edge stepping, which
// unfortunately requires divisions in the setup phase to get right,
// it should probably only be used for relatively large trianges


// x = y*DX/DY    (ou DX and DY are constants, DY > 0, et y >= 0)
// 
// for an equation of the type:
//      x' = y*K/2^p     (with K and p constants "carefully chosen")
// 
// We can now do a DDA without precision loss. We define 'e' by:
//      x' - x = y*(DX/DY - K/2^p) = y*e
// 
// If we choose K = round(DX*2^p/DY) then,
//      abs(e) <= 1/2^(p+1) by construction
// 
// therefore abs(x'-x) = y*abs(e) <= y/2^(p+1) <= DY/2^(p+1) <= DMAX/2^(p+1)
// 
// which means that if DMAX <= 2^p, therefore abs(x-x') <= 1/2, including
// at the last line. In fact, it's even a strict inequality except in one
// extrem case (DY == DMAX et e = +/- 1/2)
// 
// Applying that to our coordinates, we need 2^p >= 4096*16 = 65536
// so p = 16 is enough, we're so lucky!

const int TRI_ITERATORS_BITS = 16;

struct Edge
{
  int32_t  x;      // edge position in 16.16 coordinates
  int32_t  x_incr; // on each step, increment x by that amount
  int32_t  y_top;  // starting scanline, 16.4 format
  int32_t  y_bot;
};

static void
edge_dump( Edge*  edge )
{
  ALOGI( "  top=%d (%.3f)  bot=%d (%.3f)  x=%d (%.3f)  ix=%d (%.3f)",
        edge->y_top, edge->y_top/float(TRI_ONE),
		edge->y_bot, edge->y_bot/float(TRI_ONE),
		edge->x, edge->x/float(FIXED_ONE),
		edge->x_incr, edge->x_incr/float(FIXED_ONE) );
}

static void
triangle_dump_edges( Edge*  edges,
                     int            count )
{ 
    ALOGI( "%d edge%s:\n", count, count == 1 ? "" : "s" );
	for ( ; count > 0; count--, edges++ )
	  edge_dump( edges );
}

// the following function sets up an edge, it assumes
// that ymin and ymax are in already in the 'reduced'
// format
static __attribute__((noinline))
void edge_setup(
        Edge*           edges,
        int*            pcount,
        const GGLcoord* p1,
        const GGLcoord* p2,
        int32_t         ymin,
        int32_t         ymax )
{
	const GGLfixed*  top = p1;
	const GGLfixed*  bot = p2;
	Edge*    edge = edges + *pcount;

	if (top[1] > bot[1]) {
        swap(top, bot);
	}

	int  y1 = top[1] | 1;
	int  y2 = bot[1] | 1;
	int  dy = y2 - y1;

	if ( dy == 0 || y1 > ymax || y2 < ymin )
		return;

	if ( y1 > ymin )
		ymin = TRI_SNAP_NEXT_HALF(y1);
	
	if ( y2 < ymax )
		ymax = TRI_SNAP_PREV_HALF(y2);

	if ( ymin > ymax )  // when the edge doesn't cross any scanline
	  return;

	const int x1 = top[0];
	const int dx = bot[0] - x1;
    const int shift = TRI_ITERATORS_BITS - TRI_FRACTION_BITS;

	// setup edge fields
    // We add 0.5 to edge->x here because it simplifies the rounding
    // in triangle_sweep_edges() -- this doesn't change the ordering of 'x'
	edge->x      = (x1 << shift) + (1LU << (TRI_ITERATORS_BITS-1));
	edge->x_incr = 0;
	edge->y_top  = ymin;
	edge->y_bot  = ymax;

	if (ggl_likely(ymin <= ymax && dx)) {
        edge->x_incr = gglDivQ16(dx, dy);
    }
    if (ggl_likely(y1 < ymin)) {
        int32_t xadjust = (edge->x_incr * (ymin-y1)) >> TRI_FRACTION_BITS;
        edge->x += xadjust;
    }
  
	++*pcount;
}


static void
triangle_sweep_edges( Edge*  left,
                      Edge*  right,
					  int            ytop,
					  int            ybot,
					  context_t*     c )
{
    int count = ((ybot - ytop)>>TRI_FRACTION_BITS) + 1;
    if (count<=0) return;

    // sort the edges horizontally
    if ((left->x > right->x) || 
        ((left->x == right->x) && (left->x_incr > right->x_incr))) {
        swap(left, right);
    }

    int left_x = left->x;
    int right_x = right->x;
    const int left_xi = left->x_incr;
    const int right_xi  = right->x_incr;
    left->x  += left_xi * count;
    right->x += right_xi * count;

	const int xmin = c->state.scissor.left;
	const int xmax = c->state.scissor.right;
    do {
        // horizontal scissoring
        const int32_t xl = max(left_x  >> TRI_ITERATORS_BITS, xmin);
        const int32_t xr = min(right_x >> TRI_ITERATORS_BITS, xmax);
        left_x  += left_xi;
        right_x += right_xi;
        // invoke the scanline rasterizer
        if (ggl_likely(xl < xr)) {
            c->iterators.xl = xl;
            c->iterators.xr = xr;
            c->scanline(c);
        }
		c->step_y(c);
	} while (--count);
}


void trianglex_big(void* con,
        const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
{
    GGL_CONTEXT(c, con);

    Edge edges[3];
	int num_edges = 0;
	int32_t ymin = TRI_FROM_INT(c->state.scissor.top)    + TRI_HALF;
	int32_t ymax = TRI_FROM_INT(c->state.scissor.bottom) - TRI_HALF;
	    
	edge_setup( edges, &num_edges, v0, v1, ymin, ymax );
	edge_setup( edges, &num_edges, v0, v2, ymin, ymax );
	edge_setup( edges, &num_edges, v1, v2, ymin, ymax );

    if (ggl_unlikely(num_edges<2))  // for really tiny triangles that don't
		return;                     // cross any scanline centers

    Edge* left  = &edges[0];
    Edge* right = &edges[1];
    Edge* other = &edges[2];
    int32_t y_top = min(left->y_top, right->y_top);
    int32_t y_bot = max(left->y_bot, right->y_bot);

	if (ggl_likely(num_edges==3)) {
        y_top = min(y_top, edges[2].y_top);
        y_bot = max(y_bot, edges[2].y_bot);
		if (edges[0].y_top > y_top) {
            other = &edges[0];
            left  = &edges[2];
		} else if (edges[1].y_top > y_top) {
            other = &edges[1];
            right = &edges[2];
		}
    }

    c->init_y(c, y_top >> TRI_FRACTION_BITS);

    int32_t y_mid = min(left->y_bot, right->y_bot);
    triangle_sweep_edges( left, right, y_top, y_mid, c );

    // second scanline sweep loop, if necessary
    y_mid += TRI_ONE;
    if (y_mid <= y_bot) {
        ((left->y_bot == y_bot) ? right : left) = other;
        if (other->y_top < y_mid) {
            other->x += other->x_incr;
        }
        triangle_sweep_edges( left, right, y_mid, y_bot, c );
    }
}

void aa_trianglex(void* con,
        const GGLcoord* a, const GGLcoord* b, const GGLcoord* c)
{
    GGLcoord pts[6] = { a[0], a[1], b[0], b[1], c[0], c[1] };
    aapolyx(con, pts, 3);
}

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#endif

struct AAEdge
{
    GGLfixed x;         // edge position in 12.16 coordinates
    GGLfixed x_incr;    // on each y step, increment x by that amount
    GGLfixed y_incr;    // on each x step, increment y by that amount
    int16_t y_top;      // starting scanline, 12.4 format
    int16_t y_bot;      // starting scanline, 12.4 format
    void dump();
};

void AAEdge::dump()
{
    float tri  = 1.0f / TRI_ONE;
    float iter = 1.0f / (1<<TRI_ITERATORS_BITS);
    float fix  = 1.0f / FIXED_ONE;
    ALOGD(   "x=%08x (%.3f), "
            "x_incr=%08x (%.3f), y_incr=%08x (%.3f), "
            "y_top=%08x (%.3f), y_bot=%08x (%.3f) ",
        x, x*fix,
        x_incr, x_incr*iter,
        y_incr, y_incr*iter,
        y_top, y_top*tri,
        y_bot, y_bot*tri );
}

// the following function sets up an edge, it assumes
// that ymin and ymax are in already in the 'reduced'
// format
static __attribute__((noinline))
void aa_edge_setup(
        AAEdge*         edges,
        int*            pcount,
        const GGLcoord* p1,
        const GGLcoord* p2,
        int32_t         ymin,
        int32_t         ymax )
{
    const GGLfixed*  top = p1;
    const GGLfixed*  bot = p2;
    AAEdge* edge = edges + *pcount;

    if (top[1] > bot[1])
        swap(top, bot);

    int  y1 = top[1];
    int  y2 = bot[1];
    int  dy = y2 - y1;

    if (dy==0 || y1>ymax || y2<ymin)
        return;

    if (y1 > ymin)
        ymin = y1;
    
    if (y2 < ymax)
        ymax = y2;

    const int x1 = top[0];
    const int dx = bot[0] - x1;
    const int shift = FIXED_BITS - TRI_FRACTION_BITS;

    // setup edge fields
    edge->x      = x1 << shift;
    edge->x_incr = 0;
    edge->y_top  = ymin;
    edge->y_bot  = ymax;
    edge->y_incr = 0x7FFFFFFF;

    if (ggl_likely(ymin <= ymax && dx)) {
        edge->x_incr = gglDivQ16(dx, dy);
        if (dx != 0) {
            edge->y_incr = abs(gglDivQ16(dy, dx));
        }
    }
    if (ggl_likely(y1 < ymin)) {
        int32_t xadjust = (edge->x_incr * (ymin-y1))
                >> (TRI_FRACTION_BITS + TRI_ITERATORS_BITS - FIXED_BITS);
        edge->x += xadjust;
    }
  
    ++*pcount;
}


typedef int (*compar_t)(const void*, const void*);
static int compare_edges(const AAEdge *e0, const AAEdge *e1) {
    if (e0->y_top > e1->y_top)      return 1;
    if (e0->y_top < e1->y_top)      return -1;
    if (e0->x > e1->x)              return 1;
    if (e0->x < e1->x)              return -1;
    if (e0->x_incr > e1->x_incr)    return 1;
    if (e0->x_incr < e1->x_incr)    return -1;
    return 0; // same edges, should never happen
}

static inline 
void SET_COVERAGE(int16_t*& p, int32_t value, ssize_t n)
{
    android_memset16((uint16_t*)p, value, n*2);
    p += n;
}

static inline 
void ADD_COVERAGE(int16_t*& p, int32_t value)
{
    value = *p + value;
    if (value >= 0x8000)
        value = 0x7FFF;
    *p++ = value;
}

static inline
void SUB_COVERAGE(int16_t*& p, int32_t value)
{
    value = *p - value;
    value &= ~(value>>31);
    *p++ = value;
}

void aapolyx(void* con,
        const GGLcoord* pts, int count)
{
    /*
     * NOTE: This routine assumes that the polygon has been clipped to the
     * viewport already, that is, no vertex lies outside of the framebuffer.
     * If this happens, the code below won't corrupt memory but the 
     * coverage values may not be correct.
     */
    
    GGL_CONTEXT(c, con);

    // we do only quads for now (it's used for thick lines)
    if ((count>4) || (count<2)) return;

    // take scissor into account
    const int xmin = c->state.scissor.left;
    const int xmax = c->state.scissor.right;
    if (xmin >= xmax) return;

    // generate edges from the vertices
    int32_t ymin = TRI_FROM_INT(c->state.scissor.top);
    int32_t ymax = TRI_FROM_INT(c->state.scissor.bottom);
    if (ymin >= ymax) return;

    AAEdge edges[4];
    int num_edges = 0;
    GGLcoord const * p = pts;
    for (int i=0 ; i<count-1 ; i++, p+=2) {
        aa_edge_setup(edges, &num_edges, p, p+2, ymin, ymax);
    }
    aa_edge_setup(edges, &num_edges, p, pts, ymin, ymax );
    if (ggl_unlikely(num_edges<2))
        return;

    // sort the edge list top to bottom, left to right.
    qsort(edges, num_edges, sizeof(AAEdge), (compar_t)compare_edges);

    int16_t* const covPtr = c->state.buffers.coverage;
    memset(covPtr+xmin, 0, (xmax-xmin)*sizeof(*covPtr));

    // now, sweep all edges in order
    // start with the 2 first edges. We know that they share their top
    // vertex, by construction.
    int i = 2;
    AAEdge* left  = &edges[0];
    AAEdge* right = &edges[1];
    int32_t yt = left->y_top;
    GGLfixed l = left->x;
    GGLfixed r = right->x;
    int retire = 0;
    int16_t* coverage;

    // at this point we can initialize the rasterizer    
    c->init_y(c, yt>>TRI_FRACTION_BITS);
    c->iterators.xl = xmax;
    c->iterators.xr = xmin;

    do {
        int32_t y = min(min(left->y_bot, right->y_bot), TRI_FLOOR(yt + TRI_ONE));
        const int32_t shift = TRI_FRACTION_BITS + TRI_ITERATORS_BITS - FIXED_BITS;
        const int cf_shift = (1 + TRI_FRACTION_BITS*2 + TRI_ITERATORS_BITS - 15);

        // compute xmin and xmax for the left edge
        GGLfixed l_min = gglMulAddx(left->x_incr, y - left->y_top, left->x, shift);
        GGLfixed l_max = l;
        l = l_min;
        if (l_min > l_max)
            swap(l_min, l_max);

        // compute xmin and xmax for the right edge
        GGLfixed r_min = gglMulAddx(right->x_incr, y - right->y_top, right->x, shift);
        GGLfixed r_max = r;
        r = r_min;
        if (r_min > r_max)
            swap(r_min, r_max);

        // make sure we're not touching coverage values outside of the
        // framebuffer
        l_min &= ~(l_min>>31);
        r_min &= ~(r_min>>31);
        l_max &= ~(l_max>>31);
        r_max &= ~(r_max>>31);
        if (gglFixedToIntFloor(l_min) >= xmax) l_min = gglIntToFixed(xmax)-1;
        if (gglFixedToIntFloor(r_min) >= xmax) r_min = gglIntToFixed(xmax)-1;
        if (gglFixedToIntCeil(l_max) >= xmax)  l_max = gglIntToFixed(xmax)-1;
        if (gglFixedToIntCeil(r_max) >= xmax)  r_max = gglIntToFixed(xmax)-1;

        // compute the integer versions of the above
        const GGLfixed l_min_i = gglFloorx(l_min);
        const GGLfixed l_max_i = gglCeilx (l_max);
        const GGLfixed r_min_i = gglFloorx(r_min);
        const GGLfixed r_max_i = gglCeilx (r_max);

        // clip horizontally using the scissor
        const int xml = max(xmin, gglFixedToIntFloor(l_min_i));
        const int xmr = min(xmax, gglFixedToIntFloor(r_max_i));

        // if we just stepped to a new scanline, render the previous one.
        // and clear the coverage buffer
        if (retire) {
            if (c->iterators.xl < c->iterators.xr)
                c->scanline(c);
            c->step_y(c);
            memset(covPtr+xmin, 0, (xmax-xmin)*sizeof(*covPtr));
            c->iterators.xl = xml;
            c->iterators.xr = xmr;
        } else {
            // update the horizontal range of this scanline
            c->iterators.xl = min(c->iterators.xl, xml);
            c->iterators.xr = max(c->iterators.xr, xmr);
        }

        coverage = covPtr + gglFixedToIntFloor(l_min_i);
        if (l_min_i == gglFloorx(l_max)) {
            
            /*
             *  fully traverse this pixel vertically
             *       l_max
             *  +-----/--+  yt
             *  |    /   |  
             *  |   /    |
             *  |  /     |
             *  +-/------+  y
             *   l_min  (l_min_i + TRI_ONE)
             */
              
            GGLfixed dx = l_max - l_min;
            int32_t dy = y - yt;
            int cf = gglMulx((dx >> 1) + (l_min_i + FIXED_ONE - l_max), dy,
                FIXED_BITS + TRI_FRACTION_BITS - 15);
            ADD_COVERAGE(coverage, cf);
            // all pixels on the right have cf = 1.0
        } else {
            /*
             *  spans several pixels in one scanline
             *            l_max
             *  +--------+--/-----+  yt
             *  |        |/       |
             *  |       /|        |
             *  |     /  |        |
             *  +---/----+--------+  y
             *   l_min (l_min_i + TRI_ONE)
             */

            // handle the first pixel separately...
            const int32_t y_incr = left->y_incr;
            int32_t dx = TRI_FROM_FIXED(l_min_i - l_min) + TRI_ONE;
            int32_t cf = (dx * dx * y_incr) >> cf_shift;
            ADD_COVERAGE(coverage, cf);

            // following pixels get covered by y_incr, but we need
            // to fix-up the cf to account for previous partial pixel
            dx = TRI_FROM_FIXED(l_min - l_min_i);
            cf -= (dx * dx * y_incr) >> cf_shift;
            for (int x = l_min_i+FIXED_ONE ; x < l_max_i-FIXED_ONE ; x += FIXED_ONE) {
                cf += y_incr >> (TRI_ITERATORS_BITS-15);
                ADD_COVERAGE(coverage, cf);
            }
            
            // and the last pixel
            dx = TRI_FROM_FIXED(l_max - l_max_i) - TRI_ONE;
            cf += (dx * dx * y_incr) >> cf_shift;
            ADD_COVERAGE(coverage, cf);
        }
        
        // now, fill up all fully covered pixels
        coverage = covPtr + gglFixedToIntFloor(l_max_i);
        int cf = ((y - yt) << (15 - TRI_FRACTION_BITS));
        if (ggl_likely(cf >= 0x8000)) {
            SET_COVERAGE(coverage, 0x7FFF, ((r_max - l_max_i)>>FIXED_BITS)+1);
        } else {
            for (int x=l_max_i ; x<r_max ; x+=FIXED_ONE) {
                ADD_COVERAGE(coverage, cf);
            }
        }
        
        // subtract the coverage of the right edge
        coverage = covPtr + gglFixedToIntFloor(r_min_i); 
        if (r_min_i == gglFloorx(r_max)) {
            GGLfixed dx = r_max - r_min;
            int32_t dy = y - yt;
            int cf = gglMulx((dx >> 1) + (r_min_i + FIXED_ONE - r_max), dy,
                FIXED_BITS + TRI_FRACTION_BITS - 15);
            SUB_COVERAGE(coverage, cf);
            // all pixels on the right have cf = 1.0
        } else {
            // handle the first pixel separately...
            const int32_t y_incr = right->y_incr;
            int32_t dx = TRI_FROM_FIXED(r_min_i - r_min) + TRI_ONE;
            int32_t cf = (dx * dx * y_incr) >> cf_shift;
            SUB_COVERAGE(coverage, cf);
            
            // following pixels get covered by y_incr, but we need
            // to fix-up the cf to account for previous partial pixel
            dx = TRI_FROM_FIXED(r_min - r_min_i);
            cf -= (dx * dx * y_incr) >> cf_shift;
            for (int x = r_min_i+FIXED_ONE ; x < r_max_i-FIXED_ONE ; x += FIXED_ONE) {
                cf += y_incr >> (TRI_ITERATORS_BITS-15);
                SUB_COVERAGE(coverage, cf);
            }
            
            // and the last pixel
            dx = TRI_FROM_FIXED(r_max - r_max_i) - TRI_ONE;
            cf += (dx * dx * y_incr) >> cf_shift;
            SUB_COVERAGE(coverage, cf);
        }

        // did we reach the end of an edge? if so, get a new one.
        if (y == left->y_bot || y == right->y_bot) {
            // bail out if we're done
            if (i>=num_edges)
                break;
            if (y == left->y_bot)
                left = &edges[i++];
            if (y == right->y_bot)
                right = &edges[i++];
        }

        // next scanline
        yt = y;
        
        // did we just finish a scanline?        
        retire = (y << (32-TRI_FRACTION_BITS)) == 0;
    } while (true);

    // render the last scanline
    if (c->iterators.xl < c->iterators.xr)
        c->scanline(c);
}

}; // namespace android