aboutsummaryrefslogtreecommitdiffhomepage
path: root/tests/PathOpsAngleIdeas.cpp
blob: 9d1b5994b2da91dde992ee0ed23108ed9d7a3783 (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
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
/*
 * Copyright 2013 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
#include "PathOpsTestCommon.h"
#include "SkIntersections.h"
#include "SkOpContour.h"
#include "SkOpSegment.h"
#include "SkRandom.h"
#include "SkTArray.h"
#include "SkTSort.h"
#include "Test.h"

static bool gPathOpsAngleIdeasVerbose = false;
static bool gPathOpsAngleIdeasEnableBruteCheck = false;

class PathOpsAngleTester {
public:
    static int ConvexHullOverlaps(SkOpAngle& lh, SkOpAngle& rh) {
        return lh.convexHullOverlaps(&rh);
    }

    static int EndsIntersect(SkOpAngle& lh, SkOpAngle& rh) {
        return lh.endsIntersect(&rh);
    }
};

struct TRange {
    double tMin1;
    double tMin2;
    double t1;
    double t2;
    double tMin;
    double a1;
    double a2;
    bool ccw;
};

static double testArc(skiatest::Reporter* reporter, const SkDQuad& quad, const SkDQuad& arcRef,
        int octant) {
    SkDQuad arc = arcRef;
    SkDVector offset = {quad[0].fX, quad[0].fY};
    arc[0] += offset;
    arc[1] += offset;
    arc[2] += offset;
    SkIntersections i;
    i.intersect(arc, quad);
    if (i.used() == 0) {
        return -1;
    }
    int smallest = -1;
    double t = 2;
    for (int idx = 0; idx < i.used(); ++idx) {
        if (i[0][idx] > 1 || i[0][idx] < 0) {
            i.reset();
            i.intersect(arc, quad);
        }
        if (i[1][idx] > 1 || i[1][idx] < 0) {
            i.reset();
            i.intersect(arc, quad);
        }
        if (t > i[1][idx]) {
            smallest = idx;
            t = i[1][idx];
        }
    }
    REPORTER_ASSERT(reporter, smallest >= 0);
    REPORTER_ASSERT(reporter, t >= 0 && t <= 1);
    return i[1][smallest];
}

static void orderQuads(skiatest::Reporter* reporter, const SkDQuad& quad, double radius,
        SkTArray<double, false>* tArray) {
    double r = radius;
    double s = r * SK_ScalarTanPIOver8;
    double m = r * SK_ScalarRoot2Over2;
    // construct circle from quads
    const SkDQuad circle[8] = {{{{ r,  0}, { r, -s}, { m, -m}}},
                                {{{ m, -m}, { s, -r}, { 0, -r}}},
                                {{{ 0, -r}, {-s, -r}, {-m, -m}}},
                                {{{-m, -m}, {-r, -s}, {-r,  0}}},
                                {{{-r,  0}, {-r,  s}, {-m,  m}}},
                                {{{-m,  m}, {-s,  r}, { 0,  r}}},
                                {{{ 0,  r}, { s,  r}, { m,  m}}},
                                {{{ m,  m}, { r,  s}, { r,  0}}}};
    for (int octant = 0; octant < 8; ++octant) {
        double t = testArc(reporter, quad, circle[octant], octant);
        if (t < 0) {
            continue;
        }
        for (int index = 0; index < tArray->count(); ++index) {
            double matchT = (*tArray)[index];
            if (approximately_equal(t, matchT)) {
                goto next;
            }
        }
        tArray->push_back(t);
next:   ;
    }
}

static double quadAngle(skiatest::Reporter* reporter, const SkDQuad& quad, double t) {
    const SkDVector& pt = quad.ptAtT(t) - quad[0];
    double angle = (atan2(pt.fY, pt.fX) + SK_ScalarPI) * 8 / (SK_ScalarPI * 2);
    REPORTER_ASSERT(reporter, angle >= 0 && angle <= 8);
    return angle;
}

static bool angleDirection(double a1, double a2) {
    double delta = a1 - a2;
    return (delta < 4 && delta > 0) || delta < -4;
}

static void setQuadHullSweep(const SkDQuad& quad, SkDVector sweep[2]) {
    sweep[0] = quad[1] - quad[0];
    sweep[1] = quad[2] - quad[0];
}

static double distEndRatio(double dist, const SkDQuad& quad) {
    SkDVector v[] = {quad[2] - quad[0], quad[1] - quad[0], quad[2] - quad[1]};
    double longest = SkTMax(v[0].length(), SkTMax(v[1].length(), v[2].length()));
    return longest / dist;
}

static bool checkParallel(skiatest::Reporter* reporter, const SkDQuad& quad1, const SkDQuad& quad2) {
    SkDVector sweep[2], tweep[2];
    setQuadHullSweep(quad1, sweep);
    setQuadHullSweep(quad2, tweep);
    // if the ctrl tangents are not nearly parallel, use them
    // solve for opposite direction displacement scale factor == m
    // initial dir = v1.cross(v2) == v2.x * v1.y - v2.y * v1.x
    // displacement of q1[1] : dq1 = { -m * v1.y, m * v1.x } + q1[1]
    // straight angle when : v2.x * (dq1.y - q1[0].y) == v2.y * (dq1.x - q1[0].x)
    //                       v2.x * (m * v1.x + v1.y) == v2.y * (-m * v1.y + v1.x)
    // - m * (v2.x * v1.x + v2.y * v1.y) == v2.x * v1.y - v2.y * v1.x
    // m = (v2.y * v1.x - v2.x * v1.y) / (v2.x * v1.x + v2.y * v1.y)
    // m = v1.cross(v2) / v1.dot(v2)
    double s0dt0 = sweep[0].dot(tweep[0]);
    REPORTER_ASSERT(reporter, s0dt0 != 0);
    double s0xt0 = sweep[0].crossCheck(tweep[0]);
    double m = s0xt0 / s0dt0;
    double sDist = sweep[0].length() * m;
    double tDist = tweep[0].length() * m;
    bool useS = fabs(sDist) < fabs(tDist);
    double mFactor = fabs(useS ? distEndRatio(sDist, quad1) : distEndRatio(tDist, quad2));
    if (mFactor < 5000) {  // empirically found limit
        return s0xt0 < 0;
    }
    SkDVector m0 = quad1.ptAtT(0.5) - quad1[0];
    SkDVector m1 = quad2.ptAtT(0.5) - quad2[0];
    return m0.crossCheck(m1) < 0;
}

/* returns
   -1 if overlaps
    0 if no overlap cw
    1 if no overlap ccw
*/
static int quadHullsOverlap(skiatest::Reporter* reporter, const SkDQuad& quad1,
        const SkDQuad& quad2) {
    SkDVector sweep[2], tweep[2];
    setQuadHullSweep(quad1, sweep);
    setQuadHullSweep(quad2, tweep);
    double s0xs1 = sweep[0].crossCheck(sweep[1]);
    double s0xt0 = sweep[0].crossCheck(tweep[0]);
    double s1xt0 = sweep[1].crossCheck(tweep[0]);
    bool tBetweenS = s0xs1 > 0 ? s0xt0 > 0 && s1xt0 < 0 : s0xt0 < 0 && s1xt0 > 0;
    double s0xt1 = sweep[0].crossCheck(tweep[1]);
    double s1xt1 = sweep[1].crossCheck(tweep[1]);
    tBetweenS |= s0xs1 > 0 ? s0xt1 > 0 && s1xt1 < 0 : s0xt1 < 0 && s1xt1 > 0;
    double t0xt1 = tweep[0].crossCheck(tweep[1]);
    if (tBetweenS) {
        return -1;
    }
    if ((s0xt0 == 0 && s1xt1 == 0) || (s1xt0 == 0 && s0xt1 == 0)) {  // s0 to s1 equals t0 to t1
        return -1;
    }
    bool sBetweenT = t0xt1 > 0 ? s0xt0 < 0 && s0xt1 > 0 : s0xt0 > 0 && s0xt1 < 0;
    sBetweenT |= t0xt1 > 0 ? s1xt0 < 0 && s1xt1 > 0 : s1xt0 > 0 && s1xt1 < 0;
    if (sBetweenT) {
        return -1;
    }
    // if all of the sweeps are in the same half plane, then the order of any pair is enough
    if (s0xt0 >= 0 && s0xt1 >= 0 && s1xt0 >= 0 && s1xt1 >= 0) {
        return 0;
    }
    if (s0xt0 <= 0 && s0xt1 <= 0 && s1xt0 <= 0 && s1xt1 <= 0) {
        return 1;
    }
    // if the outside sweeps are greater than 180 degress:
        // first assume the inital tangents are the ordering
        // if the midpoint direction matches the inital order, that is enough
    SkDVector m0 = quad1.ptAtT(0.5) - quad1[0];
    SkDVector m1 = quad2.ptAtT(0.5) - quad2[0];
    double m0xm1 = m0.crossCheck(m1);
    if (s0xt0 > 0 && m0xm1 > 0) {
        return 0;
    }
    if (s0xt0 < 0 && m0xm1 < 0) {
        return 1;
    }
    REPORTER_ASSERT(reporter, s0xt0 != 0);
    return checkParallel(reporter, quad1, quad2);
}

static double radianSweep(double start, double end) {
    double sweep = end - start;
    if (sweep > SK_ScalarPI) {
        sweep -= 2 * SK_ScalarPI;
    } else if (sweep < -SK_ScalarPI) {
        sweep += 2 * SK_ScalarPI;
    }
    return sweep;
}

static bool radianBetween(double start, double test, double end) {
    double startToEnd = radianSweep(start, end);
    double startToTest = radianSweep(start, test);
    double testToEnd = radianSweep(test, end);
    return (startToTest <= 0 && testToEnd <= 0 && startToTest >= startToEnd) ||
        (startToTest >= 0 && testToEnd >= 0 && startToTest <= startToEnd);
}

static bool orderTRange(skiatest::Reporter* reporter, const SkDQuad& quad1, const SkDQuad& quad2,
        double r, TRange* result) {
    SkTArray<double, false> t1Array, t2Array;
    orderQuads(reporter, quad1, r, &t1Array);
    orderQuads(reporter,quad2, r, &t2Array);
    if (!t1Array.count() || !t2Array.count()) {
        return false;
    }
    SkTQSort<double>(t1Array.begin(), t1Array.end() - 1);
    SkTQSort<double>(t2Array.begin(), t2Array.end() - 1);
    double t1 = result->tMin1 = t1Array[0];
    double t2 = result->tMin2 = t2Array[0];
    double a1 = quadAngle(reporter,quad1, t1);
    double a2 = quadAngle(reporter,quad2, t2);
    if (approximately_equal(a1, a2)) {
        return false;
    }
    bool refCCW = angleDirection(a1, a2);
    result->t1 = t1;
    result->t2 = t2;
    result->tMin = SkTMin(t1, t2);
    result->a1 = a1;
    result->a2 = a2;
    result->ccw = refCCW;
    return true;
}

static bool equalPoints(const SkDPoint& pt1, const SkDPoint& pt2, double max) {
    return approximately_zero_when_compared_to(pt1.fX - pt2.fX, max)
            && approximately_zero_when_compared_to(pt1.fY - pt2.fY, max);
}

static double maxDist(const SkDQuad& quad) {
    SkDRect bounds;
    bounds.setBounds(quad);
    SkDVector corner[4] = {
        { bounds.fLeft - quad[0].fX, bounds.fTop - quad[0].fY },
        { bounds.fRight - quad[0].fX, bounds.fTop - quad[0].fY },
        { bounds.fLeft - quad[0].fX, bounds.fBottom - quad[0].fY },
        { bounds.fRight - quad[0].fX, bounds.fBottom - quad[0].fY }
    };
    double max = 0;
    for (unsigned index = 0; index < SK_ARRAY_COUNT(corner); ++index) {
        max = SkTMax(max, corner[index].length());
    }
    return max;
}

static double maxQuad(const SkDQuad& quad) {
    double max = 0;
    for (int index = 0; index < 2; ++index) {
        max = SkTMax(max, fabs(quad[index].fX));
        max = SkTMax(max, fabs(quad[index].fY));
    }
    return max;
}

static bool bruteMinT(skiatest::Reporter* reporter, const SkDQuad& quad1, const SkDQuad& quad2,
        TRange* lowerRange, TRange* upperRange) {
    double maxRadius = SkTMin(maxDist(quad1), maxDist(quad2));
    double maxQuads = SkTMax(maxQuad(quad1), maxQuad(quad2));
    double r = maxRadius / 2;
    double rStep = r / 2;
    SkDPoint best1 = {SK_ScalarInfinity, SK_ScalarInfinity};
    SkDPoint best2 = {SK_ScalarInfinity, SK_ScalarInfinity};
    int bestCCW = -1;
    double bestR = maxRadius;
    upperRange->tMin = 0;
    lowerRange->tMin = 1;
    do {
        do {  // find upper bounds of single result
            TRange tRange;
            bool stepUp = orderTRange(reporter, quad1, quad2, r, &tRange);
            if (stepUp) {
                SkDPoint pt1 = quad1.ptAtT(tRange.t1);
                if (equalPoints(pt1, best1, maxQuads)) {
                    break;
                }
                best1 = pt1;
                SkDPoint pt2 = quad2.ptAtT(tRange.t2);
                if (equalPoints(pt2, best2, maxQuads)) {
                    break;
                }
                best2 = pt2;
                if (gPathOpsAngleIdeasVerbose) {
                    SkDebugf("u bestCCW=%d ccw=%d bestMin=%1.9g:%1.9g r=%1.9g tMin=%1.9g\n",
                            bestCCW, tRange.ccw, lowerRange->tMin, upperRange->tMin, r,
                            tRange.tMin);
                }
                if (bestCCW >= 0 && bestCCW != (int) tRange.ccw) {
                    if (tRange.tMin < upperRange->tMin) {
                        upperRange->tMin = 0;
                    } else {
                        stepUp = false;
                    }
                }
                if (upperRange->tMin < tRange.tMin) {
                    bestCCW = tRange.ccw;
                    bestR = r;
                    *upperRange = tRange;
                }
                if (lowerRange->tMin > tRange.tMin) {
                    *lowerRange = tRange;
                }
            }
            r += stepUp ? rStep : -rStep;
            rStep /= 2;
        } while (rStep > FLT_EPSILON);
        if (bestCCW < 0) {
            REPORTER_ASSERT(reporter, bestR < maxRadius);
            return false;
        }
        double lastHighR = bestR;
        r = bestR / 2;
        rStep = r / 2;
        do {  // find lower bounds of single result
            TRange tRange;
            bool success = orderTRange(reporter, quad1, quad2, r, &tRange);
            if (success) {
                if (gPathOpsAngleIdeasVerbose) {
                    SkDebugf("l bestCCW=%d ccw=%d bestMin=%1.9g:%1.9g r=%1.9g tMin=%1.9g\n",
                            bestCCW, tRange.ccw, lowerRange->tMin, upperRange->tMin, r,
                            tRange.tMin);
                }
                if (bestCCW != (int) tRange.ccw || upperRange->tMin < tRange.tMin) {
                    bestCCW = tRange.ccw;
                    *upperRange = tRange;
                    bestR = lastHighR;
                    break;  // need to establish a new upper bounds
                }
                SkDPoint pt1 = quad1.ptAtT(tRange.t1);
                SkDPoint pt2 = quad2.ptAtT(tRange.t2);
                if (equalPoints(pt1, best1, maxQuads)) {
                    goto breakOut;
                }
                best1 = pt1;
                if (equalPoints(pt2, best2, maxQuads)) {
                    goto breakOut;
                }
                best2 = pt2;
                if (equalPoints(pt1, pt2, maxQuads)) {
                    success = false;
                } else {
                    if (upperRange->tMin < tRange.tMin) {
                        *upperRange = tRange;
                    }
                    if (lowerRange->tMin > tRange.tMin) {
                        *lowerRange = tRange;
                    }
                }
                lastHighR = SkTMin(r, lastHighR);
            }
            r += success ? -rStep : rStep;
            rStep /= 2;
        } while (rStep > FLT_EPSILON);
    } while (rStep > FLT_EPSILON);
breakOut:
    if (gPathOpsAngleIdeasVerbose) {
        SkDebugf("l a2-a1==%1.9g\n", lowerRange->a2 - lowerRange->a1);
    }
    return true;
}

static void bruteForce(skiatest::Reporter* reporter, const SkDQuad& quad1, const SkDQuad& quad2,
        bool ccw) {
    if (!gPathOpsAngleIdeasEnableBruteCheck) {
        return;
    }
    TRange lowerRange, upperRange;
    bool result = bruteMinT(reporter, quad1, quad2, &lowerRange, &upperRange);
    REPORTER_ASSERT(reporter, result);
    double angle = fabs(lowerRange.a2 - lowerRange.a1);
    REPORTER_ASSERT(reporter, angle > 3.998 || ccw == upperRange.ccw);
}

static bool bruteForceCheck(skiatest::Reporter* reporter, const SkDQuad& quad1,
        const SkDQuad& quad2, bool ccw) {
    TRange lowerRange, upperRange;
    bool result = bruteMinT(reporter, quad1, quad2, &lowerRange, &upperRange);
    REPORTER_ASSERT(reporter, result);
    return ccw == upperRange.ccw;
}

static void makeSegment(SkOpContour* contour, const SkDQuad& quad, SkPoint shortQuad[3]) {
    shortQuad[0] = quad[0].asSkPoint();
    shortQuad[1] = quad[1].asSkPoint();
    shortQuad[2] = quad[2].asSkPoint();
    contour->addQuad(shortQuad);
}

static void testQuadAngles(skiatest::Reporter* reporter, const SkDQuad& quad1, const SkDQuad& quad2,
        int testNo, SkChunkAlloc* allocator) {
    SkPoint shortQuads[2][3];

    SkOpContourHead contour;
    SkOpGlobalState state(&contour, allocator  SkDEBUGPARAMS(false) SkDEBUGPARAMS(nullptr));
    contour.init(&state, false, false);
    makeSegment(&contour, quad1, shortQuads[0]);
    makeSegment(&contour, quad1, shortQuads[1]);
    SkOpSegment* seg1 = contour.first();
    seg1->debugAddAngle(0, 1);
    SkOpSegment* seg2 = seg1->next();
    seg2->debugAddAngle(0, 1);
    int realOverlap = PathOpsAngleTester::ConvexHullOverlaps(*seg1->debugLastAngle(),
            *seg2->debugLastAngle());
    const SkDPoint& origin = quad1[0];
    REPORTER_ASSERT(reporter, origin == quad2[0]);
    double a1s = atan2(origin.fY - quad1[1].fY, quad1[1].fX - origin.fX);
    double a1e = atan2(origin.fY - quad1[2].fY, quad1[2].fX - origin.fX);
    double a2s = atan2(origin.fY - quad2[1].fY, quad2[1].fX - origin.fX);
    double a2e = atan2(origin.fY - quad2[2].fY, quad2[2].fX - origin.fX);
    bool oldSchoolOverlap = radianBetween(a1s, a2s, a1e)
        || radianBetween(a1s, a2e, a1e) || radianBetween(a2s, a1s, a2e)
        || radianBetween(a2s, a1e, a2e);
    int overlap = quadHullsOverlap(reporter, quad1, quad2);
    bool realMatchesOverlap = realOverlap == overlap || SK_ScalarPI - fabs(a2s - a1s) < 0.002;
    if (realOverlap != overlap) {
        SkDebugf("\nSK_ScalarPI - fabs(a2s - a1s) = %1.9g\n", SK_ScalarPI - fabs(a2s - a1s));
    }
    if (!realMatchesOverlap) {
        DumpQ(quad1, quad2, testNo);
    }
    REPORTER_ASSERT(reporter, realMatchesOverlap);
    if (oldSchoolOverlap != (overlap < 0)) {
        overlap = quadHullsOverlap(reporter, quad1, quad2);  // set a breakpoint and debug if assert fires
        REPORTER_ASSERT(reporter, oldSchoolOverlap == (overlap < 0));
    }
    SkDVector v1s = quad1[1] - quad1[0];
    SkDVector v1e = quad1[2] - quad1[0];
    SkDVector v2s = quad2[1] - quad2[0];
    SkDVector v2e = quad2[2] - quad2[0];
    double vDir[2] = { v1s.cross(v1e), v2s.cross(v2e) };
    bool ray1In2 = v1s.cross(v2s) * vDir[1] <= 0 && v1s.cross(v2e) * vDir[1] >= 0;
    bool ray2In1 = v2s.cross(v1s) * vDir[0] <= 0 && v2s.cross(v1e) * vDir[0] >= 0;
    if (overlap >= 0) {
        // verify that hulls really don't overlap
        REPORTER_ASSERT(reporter, !ray1In2);
        REPORTER_ASSERT(reporter, !ray2In1);
        bool ctrl1In2 = v1e.cross(v2s) * vDir[1] <= 0 && v1e.cross(v2e) * vDir[1] >= 0;
        REPORTER_ASSERT(reporter, !ctrl1In2);
        bool ctrl2In1 = v2e.cross(v1s) * vDir[0] <= 0 && v2e.cross(v1e) * vDir[0] >= 0;
        REPORTER_ASSERT(reporter, !ctrl2In1);
        // check answer against reference
        bruteForce(reporter, quad1, quad2, overlap > 0);
    }
    // continue end point rays and see if they intersect the opposite curve
    SkDLine rays[] = {{{origin, quad2[2]}}, {{origin, quad1[2]}}};
    const SkDQuad* quads[] = {&quad1, &quad2};
    SkDVector midSpokes[2];
    SkIntersections intersect[2];
    double minX, minY, maxX, maxY;
    minX = minY = SK_ScalarInfinity;
    maxX = maxY = -SK_ScalarInfinity;
    double maxWidth = 0;
    bool useIntersect = false;
    double smallestTs[] = {1, 1};
    for (unsigned index = 0; index < SK_ARRAY_COUNT(quads); ++index) {
        const SkDQuad& q = *quads[index];
        midSpokes[index] = q.ptAtT(0.5) - origin;
        minX = SkTMin(SkTMin(SkTMin(minX, origin.fX), q[1].fX), q[2].fX);
        minY = SkTMin(SkTMin(SkTMin(minY, origin.fY), q[1].fY), q[2].fY);
        maxX = SkTMax(SkTMax(SkTMax(maxX, origin.fX), q[1].fX), q[2].fX);
        maxY = SkTMax(SkTMax(SkTMax(maxY, origin.fY), q[1].fY), q[2].fY);
        maxWidth = SkTMax(maxWidth, SkTMax(maxX - minX, maxY - minY));
        intersect[index].intersectRay(q, rays[index]);
        const SkIntersections& i = intersect[index];
        REPORTER_ASSERT(reporter, i.used() >= 1);
        bool foundZero = false;
        double smallT = 1;
        for (int idx2 = 0; idx2 < i.used(); ++idx2) {
            double t = i[0][idx2];
            if (t == 0) {
                foundZero = true;
                continue;
            }
            if (smallT > t) {
                smallT = t;
            }
        }
        REPORTER_ASSERT(reporter, foundZero == true);
        if (smallT == 1) {
            continue;
        }
        SkDVector ray = q.ptAtT(smallT) - origin;
        SkDVector end = rays[index][1] - origin;
        if (ray.fX * end.fX < 0 || ray.fY * end.fY < 0) {
            continue;
        }
        double rayDist = ray.length();
        double endDist = end.length();
        double delta = fabs(rayDist - endDist) / maxWidth;
        if (delta > 1e-4) {
            useIntersect ^= true;
        }
        smallestTs[index] = smallT;
    }
    bool firstInside;
    if (useIntersect) {
        int sIndex = (int) (smallestTs[1] < 1);
        REPORTER_ASSERT(reporter, smallestTs[sIndex ^ 1] == 1);
        double t = smallestTs[sIndex];
        const SkDQuad& q = *quads[sIndex];
        SkDVector ray = q.ptAtT(t) - origin;
        SkDVector end = rays[sIndex][1] - origin;
        double rayDist = ray.length();
        double endDist = end.length();
        SkDVector mid = q.ptAtT(t / 2) - origin;
        double midXray = mid.crossCheck(ray);
        if (gPathOpsAngleIdeasVerbose) {
            SkDebugf("rayDist>endDist:%d sIndex==0:%d vDir[sIndex]<0:%d midXray<0:%d\n",
                    rayDist > endDist, sIndex == 0, vDir[sIndex] < 0, midXray < 0);
        }
        SkASSERT(SkScalarSignAsInt(SkDoubleToScalar(midXray))
            == SkScalarSignAsInt(SkDoubleToScalar(vDir[sIndex])));
        firstInside = (rayDist > endDist) ^ (sIndex == 0) ^ (vDir[sIndex] < 0);
    } else if (overlap >= 0) {
        return;  // answer has already been determined
    } else {
        firstInside = checkParallel(reporter, quad1, quad2);
    }
    if (overlap < 0) {
        SkDEBUGCODE(int realEnds =)
                PathOpsAngleTester::EndsIntersect(*seg1->debugLastAngle(),
                *seg2->debugLastAngle());
        SkASSERT(realEnds == (firstInside ? 1 : 0));
    }
    bruteForce(reporter, quad1, quad2, firstInside);
}

DEF_TEST(PathOpsAngleOverlapHullsOne, reporter) {
    SkChunkAlloc allocator(4096);
//    gPathOpsAngleIdeasVerbose = true;
    const SkDQuad quads[] = {
{{{939.4808349609375, 914.355224609375}, {-357.7921142578125, 590.842529296875}, {736.8936767578125, -350.717529296875}}},
{{{939.4808349609375, 914.355224609375}, {-182.85418701171875, 634.4552001953125}, {-509.62615966796875, 576.1182861328125}}}
    };
    for (int index = 0; index < (int) SK_ARRAY_COUNT(quads); index += 2) {
        testQuadAngles(reporter, quads[index], quads[index + 1], 0, &allocator);
    }
}

DEF_TEST(PathOpsAngleOverlapHulls, reporter) {
    SkChunkAlloc allocator(4096);
    if (!gPathOpsAngleIdeasVerbose) {  // takes a while to run -- so exclude it by default
        return;
    }
    SkRandom ran;
    for (int index = 0; index < 100000; ++index) {
        if (index % 1000 == 999) SkDebugf(".");
        SkDPoint origin = {ran.nextRangeF(-1000, 1000), ran.nextRangeF(-1000, 1000)};
        SkDQuad quad1 = {{origin, {ran.nextRangeF(-1000, 1000), ran.nextRangeF(-1000, 1000)},
            {ran.nextRangeF(-1000, 1000), ran.nextRangeF(-1000, 1000)}}};
        if (quad1[0] == quad1[2]) {
            continue;
        }
        SkDQuad quad2 = {{origin, {ran.nextRangeF(-1000, 1000), ran.nextRangeF(-1000, 1000)},
            {ran.nextRangeF(-1000, 1000), ran.nextRangeF(-1000, 1000)}}};
        if (quad2[0] == quad2[2]) {
            continue;
        }
        SkIntersections i;
        i.intersect(quad1, quad2);
        REPORTER_ASSERT(reporter, i.used() >= 1);
        if (i.used() > 1) {
            continue;
        }
        testQuadAngles(reporter, quad1, quad2, index, &allocator);
    }
}

DEF_TEST(PathOpsAngleBruteT, reporter) {
    if (!gPathOpsAngleIdeasVerbose) {  // takes a while to run -- so exclude it by default
        return;
    }
    SkRandom ran;
    double smaller = SK_Scalar1;
    SkDQuad small[2];
    SkDEBUGCODE(int smallIndex);
    for (int index = 0; index < 100000; ++index) {
        SkDPoint origin = {ran.nextRangeF(-1000, 1000), ran.nextRangeF(-1000, 1000)};
        SkDQuad quad1 = {{origin, {ran.nextRangeF(-1000, 1000), ran.nextRangeF(-1000, 1000)},
            {ran.nextRangeF(-1000, 1000), ran.nextRangeF(-1000, 1000)}}};
        if (quad1[0] == quad1[2]) {
            continue;
        }
        SkDQuad quad2 = {{origin, {ran.nextRangeF(-1000, 1000), ran.nextRangeF(-1000, 1000)},
            {ran.nextRangeF(-1000, 1000), ran.nextRangeF(-1000, 1000)}}};
        if (quad2[0] == quad2[2]) {
            continue;
        }
        SkIntersections i;
        i.intersect(quad1, quad2);
        REPORTER_ASSERT(reporter, i.used() >= 1);
        if (i.used() > 1) {
            continue;
        }
        TRange lowerRange, upperRange;
        bool result = bruteMinT(reporter, quad1, quad2, &lowerRange, &upperRange);
        REPORTER_ASSERT(reporter, result);
        double min = SkTMin(upperRange.t1, upperRange.t2);
        if (smaller > min) {
            small[0] = quad1;
            small[1] = quad2;
            SkDEBUGCODE(smallIndex = index);
            smaller = min;
        }
    }
#ifdef SK_DEBUG
    DumpQ(small[0], small[1], smallIndex);
#endif
}

DEF_TEST(PathOpsAngleBruteTOne, reporter) {
//    gPathOpsAngleIdeasVerbose = true;
    const SkDQuad quads[] = {
{{{-770.8492431640625, 948.2369384765625}, {-853.37066650390625, 972.0301513671875}, {-200.62042236328125, -26.7174072265625}}},
{{{-770.8492431640625, 948.2369384765625}, {513.602783203125, 578.8681640625}, {960.641357421875, -813.69757080078125}}},
{{{563.8267822265625, -107.4566650390625}, {-44.67724609375, -136.57452392578125}, {492.3856201171875, -268.79644775390625}}},
{{{563.8267822265625, -107.4566650390625}, {708.049072265625, -100.77789306640625}, {-48.88226318359375, 967.9022216796875}}},
{{{598.857421875, 846.345458984375}, {-644.095703125, -316.12921142578125}, {-97.64599609375, 20.6158447265625}}},
{{{598.857421875, 846.345458984375}, {715.7142333984375, 955.3599853515625}, {-919.9478759765625, 691.611328125}}},
    };
    TRange lowerRange, upperRange;
    bruteMinT(reporter, quads[0], quads[1], &lowerRange, &upperRange);
    bruteMinT(reporter, quads[2], quads[3], &lowerRange, &upperRange);
    bruteMinT(reporter, quads[4], quads[5], &lowerRange, &upperRange);
}

/*
The sorting problem happens when the inital tangents are not a true indicator of the curve direction
Nearly always, the initial tangents do give the right answer,
so the trick is to figure out when the initial tangent cannot be trusted.
If the convex hulls of both curves are in the same half plane, and not overlapping, sorting the
hulls is enough.
If the hulls overlap, and have the same general direction, then intersect the shorter end point ray
with the opposing curve, and see on which side of the shorter curve the opposing intersection lies.
Otherwise, if the control vector is extremely short, likely the point on curve must be computed
If moving the control point slightly can change the sign of the cross product, either answer could
be "right".
We need to determine how short is extremely short. Move the control point a set percentage of
the largest length to determine how stable the curve is vis-a-vis the initial tangent.
*/

static const SkDQuad extremeTests[][2] = {
    {
        {{{-708.0077926931004,-154.61669472244046},
            {-707.9234268635319,-154.30459999551294},
            {505.58447265625,-504.9130859375}}},
        {{{-708.0077926931004,-154.61669472244046},
            {-711.127526325141,-163.9446090624656},
            {-32.39227294921875,-906.3277587890625}}},
    }, {
        {{{-708.0077926931004,-154.61669472244046},
            {-708.2875337527566,-154.36676458635623},
            {505.58447265625,-504.9130859375}}},
        {{{-708.0077926931004,-154.61669472244046},
            {-708.4111557216864,-154.5366642875255},
            {-32.39227294921875,-906.3277587890625}}},
    }, {
        {{{-609.0230951752058,-267.5435593490574},
            {-594.1120809906336,-136.08492475411555},
            {505.58447265625,-504.9130859375}}},
        {{{-609.0230951752058,-267.5435593490574},
            {-693.7467719138988,-341.3259237831895},
            {-32.39227294921875,-906.3277587890625}}}
    }, {
        {{{-708.0077926931004,-154.61669472244046},
            {-707.9994640658723,-154.58588461064852},
            {505.58447265625,-504.9130859375}}},
        {{{-708.0077926931004,-154.61669472244046},
            {-708.0239418990758,-154.6403553507124},
            {-32.39227294921875,-906.3277587890625}}}
    }, {
        {{{-708.0077926931004,-154.61669472244046},
            {-707.9993222215099,-154.55999389855003},
            {68.88981098017803,296.9273945411635}}},
        {{{-708.0077926931004,-154.61669472244046},
            {-708.0509091919608,-154.64675214697067},
            {-777.4871194247767,-995.1470120113145}}}
    }, {
        {{{-708.0077926931004,-154.61669472244046},
            {-708.0060491116379,-154.60889321524968},
            {229.97088707895057,-430.0569357467175}}},
        {{{-708.0077926931004,-154.61669472244046},
            {-708.013911296257,-154.6219143988058},
            {138.13162892614037,-573.3689311737394}}}
    }, {
        {{{-543.2570545751013,-237.29243831075053},
            {-452.4119186056987,-143.47223056267802},
            {229.97088707895057,-430.0569357467175}}},
        {{{-543.2570545751013,-237.29243831075053},
            {-660.5330371214436,-362.0016148388},
            {138.13162892614037,-573.3689311737394}}},
    },
};

static double endCtrlRatio(const SkDQuad quad) {
    SkDVector longEdge = quad[2] - quad[0];
    double longLen = longEdge.length();
    SkDVector shortEdge = quad[1] - quad[0];
    double shortLen = shortEdge.length();
    return longLen / shortLen;
}

static void computeMV(const SkDQuad& quad, const SkDVector& v, double m, SkDVector mV[2]) {
        SkDPoint mPta = {quad[1].fX - m * v.fY, quad[1].fY + m * v.fX};
        SkDPoint mPtb = {quad[1].fX + m * v.fY, quad[1].fY - m * v.fX};
        mV[0] = mPta - quad[0];
        mV[1] = mPtb - quad[0];
}

static double mDistance(skiatest::Reporter* reporter, bool agrees, const SkDQuad& q1,
        const SkDQuad& q2) {
    if (1 && agrees) {
        return SK_ScalarMax;
    }
    // how close is the angle from inflecting in the opposite direction?
    SkDVector v1 = q1[1] - q1[0];
    SkDVector v2 = q2[1] - q2[0];
    double dir = v1.crossCheck(v2);
    REPORTER_ASSERT(reporter, dir != 0);
    // solve for opposite direction displacement scale factor == m
    // initial dir = v1.cross(v2) == v2.x * v1.y - v2.y * v1.x
    // displacement of q1[1] : dq1 = { -m * v1.y, m * v1.x } + q1[1]
    // straight angle when : v2.x * (dq1.y - q1[0].y) == v2.y * (dq1.x - q1[0].x)
    //                       v2.x * (m * v1.x + v1.y) == v2.y * (-m * v1.y + v1.x)
    // - m * (v2.x * v1.x + v2.y * v1.y) == v2.x * v1.y - v2.y * v1.x
    // m = (v2.y * v1.x - v2.x * v1.y) / (v2.x * v1.x + v2.y * v1.y)
    // m = v1.cross(v2) / v1.dot(v2)
    double div = v1.dot(v2);
    REPORTER_ASSERT(reporter, div != 0);
    double m = dir / div;
    SkDVector mV1[2], mV2[2];
    computeMV(q1, v1, m, mV1);
    computeMV(q2, v2, m, mV2);
    double dist1 = v1.length() * m;
    double dist2 = v2.length() * m;
    if (gPathOpsAngleIdeasVerbose) {
        SkDebugf("%c r1=%1.9g r2=%1.9g m=%1.9g dist1=%1.9g dist2=%1.9g "
                " dir%c 1a=%1.9g 1b=%1.9g 2a=%1.9g 2b=%1.9g\n", agrees ? 'T' : 'F',
                endCtrlRatio(q1), endCtrlRatio(q2), m, dist1, dist2, dir > 0 ? '+' : '-',
                mV1[0].crossCheck(v2), mV1[1].crossCheck(v2),
                mV2[0].crossCheck(v1), mV2[1].crossCheck(v1));
    }
    if (1) {
        bool use1 = fabs(dist1) < fabs(dist2);
        if (gPathOpsAngleIdeasVerbose) {
            SkDebugf("%c dist=%1.9g r=%1.9g\n", agrees ? 'T' : 'F', use1 ? dist1 : dist2,
                use1 ? distEndRatio(dist1, q1) : distEndRatio(dist2, q2));
        }
        return fabs(use1 ? distEndRatio(dist1, q1) : distEndRatio(dist2, q2));
    }
    return SK_ScalarMax;
}

static void midPointAgrees(skiatest::Reporter* reporter, const SkDQuad& q1, const SkDQuad& q2,
        bool ccw) {
    SkDPoint mid1 = q1.ptAtT(0.5);
    SkDVector m1 = mid1 - q1[0];
    SkDPoint mid2 = q2.ptAtT(0.5);
    SkDVector m2 = mid2 - q2[0];
    REPORTER_ASSERT(reporter, ccw ? m1.crossCheck(m2) < 0 : m1.crossCheck(m2) > 0);
}

DEF_TEST(PathOpsAngleExtreme, reporter) {
    if (!gPathOpsAngleIdeasVerbose) {  // takes a while to run -- so exclude it by default
        return;
    }
    double maxR = SK_ScalarMax;
    for (int index = 0; index < (int) SK_ARRAY_COUNT(extremeTests); ++index) {
        const SkDQuad& quad1 = extremeTests[index][0];
        const SkDQuad& quad2 = extremeTests[index][1];
        if (gPathOpsAngleIdeasVerbose) {
            SkDebugf("%s %d\n", __FUNCTION__, index);
        }
        REPORTER_ASSERT(reporter, quad1[0] == quad2[0]);
        SkIntersections i;
        i.intersect(quad1, quad2);
        REPORTER_ASSERT(reporter, i.used() == 1);
        REPORTER_ASSERT(reporter, i.pt(0) == quad1[0]);
        int overlap = quadHullsOverlap(reporter, quad1, quad2);
        REPORTER_ASSERT(reporter, overlap >= 0);
        SkDVector sweep[2], tweep[2];
        setQuadHullSweep(quad1, sweep);
        setQuadHullSweep(quad2, tweep);
        double s0xt0 = sweep[0].crossCheck(tweep[0]);
        REPORTER_ASSERT(reporter, s0xt0 != 0);
        bool ccw = s0xt0 < 0;
        bool agrees = bruteForceCheck(reporter, quad1, quad2, ccw);
        maxR = SkTMin(maxR, mDistance(reporter, agrees, quad1, quad2));
        if (agrees) {
            continue;
        }
        midPointAgrees(reporter, quad1, quad2, !ccw);
        SkDQuad q1 = quad1;
        SkDQuad q2 = quad2;
        double loFail = 1;
        double hiPass = 2;
        // double vectors until t passes
        do {
            q1[1].fX = quad1[0].fX * (1 - hiPass) + quad1[1].fX * hiPass;
            q1[1].fY = quad1[0].fY * (1 - hiPass) + quad1[1].fY * hiPass;
            q2[1].fX = quad2[0].fX * (1 - hiPass) + quad2[1].fX * hiPass;
            q2[1].fY = quad2[0].fY * (1 - hiPass) + quad2[1].fY * hiPass;
            agrees = bruteForceCheck(reporter, q1, q2, ccw);
            maxR = SkTMin(maxR, mDistance(reporter, agrees, q1, q2));
            if (agrees) {
                break;
            }
            midPointAgrees(reporter, quad1, quad2, !ccw);
            loFail = hiPass;
            hiPass *= 2;
        } while (true);
        // binary search to find minimum pass
        double midTest = (loFail + hiPass) / 2;
        double step = (hiPass - loFail) / 4;
        while (step > FLT_EPSILON) {
            q1[1].fX = quad1[0].fX * (1 - midTest) + quad1[1].fX * midTest;
            q1[1].fY = quad1[0].fY * (1 - midTest) + quad1[1].fY * midTest;
            q2[1].fX = quad2[0].fX * (1 - midTest) + quad2[1].fX * midTest;
            q2[1].fY = quad2[0].fY * (1 - midTest) + quad2[1].fY * midTest;
            agrees = bruteForceCheck(reporter, q1, q2, ccw);
            maxR = SkTMin(maxR, mDistance(reporter, agrees, q1, q2));
            if (!agrees) {
                midPointAgrees(reporter, quad1, quad2, !ccw);
            }
            midTest += agrees ? -step : step;
            step /= 2;
        }
#ifdef SK_DEBUG
//        DumpQ(q1, q2, 999);
#endif
    }
    if (gPathOpsAngleIdeasVerbose) {
        SkDebugf("maxR=%1.9g\n", maxR);
    }
}