Home | History | Annotate | Download | only in Intersection
      1 /*
      2  * Copyright 2012 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 #include "CurveIntersection.h"
      8 #include "CurveUtilities.h"
      9 #include "CubicIntersection_TestData.h"
     10 #include "Intersection_Tests.h"
     11 #include "Intersections.h"
     12 #include "TestUtilities.h"
     13 
     14 #define SHOW_ORIGINAL 1
     15 
     16 const int firstCubicIntersectionTest = 9;
     17 
     18 static void standardTestCases() {
     19     for (size_t index = firstCubicIntersectionTest; index < tests_count; ++index) {
     20         const Cubic& cubic1 = tests[index][0];
     21         const Cubic& cubic2 = tests[index][1];
     22         Cubic reduce1, reduce2;
     23         int order1 = reduceOrder(cubic1, reduce1, kReduceOrder_NoQuadraticsAllowed,
     24             kReduceOrder_TreatAsFill);
     25         int order2 = reduceOrder(cubic2, reduce2, kReduceOrder_NoQuadraticsAllowed,
     26             kReduceOrder_TreatAsFill);
     27         if (order1 < 4) {
     28             printf("%s [%d] cubic1 order=%d\n", __FUNCTION__, (int) index, order1);
     29             continue;
     30         }
     31         if (order2 < 4) {
     32             printf("%s [%d] cubic2 order=%d\n", __FUNCTION__, (int) index, order2);
     33             continue;
     34         }
     35         if (implicit_matches(reduce1, reduce2)) {
     36             printf("%s [%d] coincident\n", __FUNCTION__, (int) index);
     37             continue;
     38         }
     39         Intersections tIntersections;
     40         intersect(reduce1, reduce2, tIntersections);
     41         if (!tIntersections.intersected()) {
     42             printf("%s [%d] no intersection\n", __FUNCTION__, (int) index);
     43             continue;
     44         }
     45         for (int pt = 0; pt < tIntersections.used(); ++pt) {
     46             double tt1 = tIntersections.fT[0][pt];
     47             double tx1, ty1;
     48             xy_at_t(cubic1, tt1, tx1, ty1);
     49             double tt2 = tIntersections.fT[1][pt];
     50             double tx2, ty2;
     51             xy_at_t(cubic2, tt2, tx2, ty2);
     52             if (!AlmostEqualUlps(tx1, tx2)) {
     53                 printf("%s [%d,%d] x!= t1=%g (%g,%g) t2=%g (%g,%g)\n",
     54                     __FUNCTION__, (int)index, pt, tt1, tx1, ty1, tt2, tx2, ty2);
     55             }
     56             if (!AlmostEqualUlps(ty1, ty2)) {
     57                 printf("%s [%d,%d] y!= t1=%g (%g,%g) t2=%g (%g,%g)\n",
     58                     __FUNCTION__, (int)index, pt, tt1, tx1, ty1, tt2, tx2, ty2);
     59             }
     60         }
     61     }
     62 }
     63 
     64 static const Cubic testSet[] = {
     65 {{67.426548091427676, 37.993772624988935}, {23.483695892376684, 90.476863174921306}, {35.597065061143162, 79.872482633158796}, {75.38634169631932, 18.244890038969412}},
     66 {{67.4265481, 37.9937726}, {23.4836959, 90.4768632}, {35.5970651, 79.8724826}, {75.3863417, 18.24489}},
     67 
     68 {{0, 0}, {0, 1}, {1, 1}, {1, 0}},
     69 {{1, 0}, {0, 0}, {0, 1}, {1, 1}},
     70 
     71 {{0,1}, {4,5}, {1,0}, {5,3}},
     72 {{0,1}, {3,5}, {1,0}, {5,4}},
     73 
     74 {{0, 1}, {1, 6}, {1, 0}, {1, 0}},
     75 {{0, 1}, {0, 1}, {1, 0}, {6, 1}},
     76 
     77 {{0,1}, {3,4}, {1,0}, {5,1}},
     78 {{0,1}, {1,5}, {1,0}, {4,3}},
     79 
     80 {{0,1}, {1,2}, {1,0}, {6,1}},
     81 {{0,1}, {1,6}, {1,0}, {2,1}},
     82 
     83 {{0,1}, {0,5}, {1,0}, {4,0}},
     84 {{0,1}, {0,4}, {1,0}, {5,0}},
     85 
     86 {{0,1}, {3,4}, {1,0}, {3,0}},
     87 {{0,1}, {0,3}, {1,0}, {4,3}},
     88 
     89 {{0, 0}, {1, 2}, {3, 4}, {4, 4}},
     90 {{0, 0}, {1, 2}, {3, 4}, {4, 4}},
     91 {{4, 4}, {3, 4}, {1, 2}, {0, 0}},
     92 
     93 {{0,1}, {2,3}, {1,0}, {1,0}},
     94 {{0,1}, {0,1}, {1,0}, {3,2}},
     95 
     96 {{0,2}, {0,1}, {1,0}, {1,0}},
     97 {{0,1}, {0,1}, {2,0}, {1,0}},
     98 
     99 {{0, 1}, {0, 2}, {1, 0}, {1, 0}},
    100 {{0, 1}, {0, 1}, {1, 0}, {2, 0}},
    101 
    102 {{0, 1}, {1, 6}, {1, 0}, {2, 0}},
    103 {{0, 1}, {0, 2}, {1, 0}, {6, 1}},
    104 
    105 {{0, 1}, {5, 6}, {1, 0}, {1, 0}},
    106 {{0, 1}, {0, 1}, {1, 0}, {6, 5}},
    107 
    108 {{95.837747722788592, 45.025976907939643}, {16.564570095652982, 0.72959763963222402}, {63.209855865319199, 68.047528419665767}, {57.640240647662544, 59.524565264361243}},
    109 {{51.593891741518817, 38.53849970667553}, {62.34752929878772, 74.924924725166022}, {74.810149322641152, 34.17966562983564}, {29.368398119401373, 94.66719277886078}},
    110 
    111 {{39.765160968417838, 33.060396198677083}, {5.1922921581157908, 66.854301452103215}, {31.619281802149157, 25.269248720849514}, {81.541621071073038, 70.025341524754353}},
    112 {{46.078911165743556, 48.259962651999651}, {20.24450549867214, 49.403916182650214}, {0.26325131778756683, 24.46489805563581}, {15.915006546264051, 83.515023059917155}},
    113 
    114 {{65.454505973241524, 93.881892270353575}, {45.867360264932437, 92.723972719499827}, {2.1464054482739447, 74.636369140183717}, {33.774068594804994, 40.770872887582925}},
    115 {{72.963387832494163, 95.659300729473728}, {11.809496633619768, 82.209921247423594}, {13.456139067865974, 57.329313623406605}, {36.060621606214262, 70.867335643091849}},
    116 
    117 {{32.484981432782945, 75.082940782924624}, {42.467313093350882, 48.131159948246157}, {3.5963115764764657, 43.208665839959245}, {79.442476890721579, 89.709102357602262}},
    118 {{18.98573861410177, 93.308887208490106}, {40.405250173250792, 91.039661826118675}, {8.0467721950480584, 42.100282172719147}, {40.883324221187891, 26.030185504830527}},
    119 
    120 {{7.5374809128872498, 82.441702896003477}, {22.444346930107265, 22.138854312775123}, {66.76091829629658, 50.753805856571446}, {78.193478508942519, 97.7932997968948}},
    121 {{97.700573130371311, 53.53260215070685}, {87.72443481149358, 84.575876772671876}, {19.215031396232092, 47.032676472809484}, {11.989686410869325, 10.659507480757082}},
    122 
    123 {{26.192053931854691, 9.8504326817814416}, {10.174241480498686, 98.476562741434464}, {21.177712558385782, 33.814968789841501}, {75.329030899018534, 55.02231980442177}},
    124 {{56.222082700683771, 24.54395039218662}, {95.589995289030483, 81.050822735322086}, {28.180450866082897, 28.837706255185282}, {60.128952916771617, 87.311672180570511}},
    125 
    126 {{42.449716172390481, 52.379709366885805}, {27.896043159019225, 48.797373636065686}, {92.770268299044233, 89.899302036454571}, {12.102066544863426, 99.43241951960718}},
    127 {{45.77532924980639, 45.958701495993274}, {37.458701356062065, 68.393691335056758}, {37.569326692060258, 27.673713456687381}, {60.674866037757539, 62.47349659096146}},
    128 
    129 {{67.426548091427676, 37.993772624988935}, {23.483695892376684, 90.476863174921306}, {35.597065061143162, 79.872482633158796}, {75.38634169631932, 18.244890038969412}},
    130 {{61.336508189019057, 82.693132843213675}, {44.639380902349664, 54.074825790745592}, {16.815615499771951, 20.049704667203923}, {41.866884958868326, 56.735503699973002}},
    131 
    132 {{67.4265481, 37.9937726}, {23.4836959, 90.4768632}, {35.5970651, 79.8724826}, {75.3863417, 18.24489}},
    133 {{61.3365082, 82.6931328}, {44.6393809, 54.0748258}, {16.8156155, 20.0497047}, {41.866885, 56.7355037}},
    134 
    135 {{18.1312339, 31.6473732}, {95.5711034, 63.5350219}, {92.3283165, 62.0158945}, {18.5656052, 32.1268808}},
    136 {{97.402018, 35.7169972}, {33.1127443, 25.8935163}, {1.13970027, 54.9424981}, {56.4860195, 60.529264}},
    137 };
    138 
    139 const size_t testSetCount = sizeof(testSet) / sizeof(testSet[0]);
    140 
    141 static const Cubic newTestSet[] = {
    142 {{1,3}, {5,6}, {5,3}, {5,4}},
    143 {{3,5}, {4,5}, {3,1}, {6,5}},
    144 
    145 {{0,5}, {0,5}, {5,4}, {6,4}},
    146 {{4,5}, {4,6}, {5,0}, {5,0}},
    147 
    148 {{0,4}, {1,3}, {5,4}, {4,2}},
    149 {{4,5}, {2,4}, {4,0}, {3,1}},
    150 
    151 {{0,2}, {1,5}, {3,2}, {4,1}},
    152 {{2,3}, {1,4}, {2,0}, {5,1}},
    153 
    154 {{0,2}, {2,3}, {5,1}, {3,2}},
    155 {{1,5}, {2,3}, {2,0}, {3,2}},
    156 
    157 {{2,6}, {4,5}, {1,0}, {6,1}},
    158 {{0,1}, {1,6}, {6,2}, {5,4}},
    159 
    160 {{0,1}, {1,2}, {6,5}, {5,4}},
    161 {{5,6}, {4,5}, {1,0}, {2,1}},
    162 
    163 {{2.5119999999999996, 1.5710000000000002}, {2.6399999999999983, 1.6599999999999997}, {2.8000000000000007, 1.8000000000000003}, {3, 2}},
    164 {{2.4181876227114887, 1.9849772580462195}, {2.8269904869227211, 2.009330650246834}, {3.2004679292461624, 1.9942047174679169}, {3.4986199496818058, 2.0035994597094731}},
    165 
    166 {{2,3}, {1,4}, {1,0}, {6,0}},
    167 {{0,1}, {0,6}, {3,2}, {4,1}},
    168 
    169 {{0,2}, {1,5}, {1,0}, {6,1}},
    170 {{0,1}, {1,6}, {2,0}, {5,1}},
    171 
    172 {{0,1}, {1,5}, {2,1}, {4,0}},
    173 {{1,2}, {0,4}, {1,0}, {5,1}},
    174 
    175 {{0,1}, {3,5}, {2,1}, {3,1}},
    176 {{1,2}, {1,3}, {1,0}, {5,3}},
    177 
    178 {{0,1}, {2,5}, {6,0}, {5,3}},
    179 {{0,6}, {3,5}, {1,0}, {5,2}},
    180 
    181 {{0,1}, {3,6}, {1,0}, {5,2}},
    182 {{0,1}, {2,5}, {1,0}, {6,3}},
    183 
    184 {{1,2},{5,6},{1,0},{1,0}},
    185 {{0,1},{0,1},{2,1},{6,5}},
    186 
    187 {{0,6},{1,2},{1,0},{1,0}},
    188 {{0,1},{0,1},{6,0},{2,1}},
    189 
    190 {{0,2},{0,1},{3,0},{1,0}},
    191 {{0,3},{0,1},{2,0},{1,0}},
    192 };
    193 
    194 const size_t newTestSetCount = sizeof(newTestSet) / sizeof(newTestSet[0]);
    195 
    196 #if 0
    197 static void oneOff(const Cubic& cubic1, const Cubic& cubic2) {
    198     SkTDArray<Quadratic> quads1;
    199     cubic_to_quadratics(cubic1, calcPrecision(cubic1), quads1);
    200 #if SHOW_ORIGINAL
    201     SkDebugf("computed quadratics given\n");
    202     SkDebugf("  {{%1.9g,%1.9g}, {%1.9g,%1.9g}, {%1.9g,%1.9g}}, {%1.9g,%1.9g}},\n",
    203         cubic1[0].x, cubic1[0].y, cubic1[1].x, cubic1[1].y,
    204         cubic1[2].x, cubic1[2].y, cubic1[3].x, cubic1[3].y));
    205     SkDebugf("  {{%1.9g,%1.9g}, {%1.9g,%1.9g}, {%1.9g,%1.9g}}, {%1.9g,%1.9g}},\n",
    206         cubic2[0].x, cubic2[0].y, cubic2[1].x, cubic2[1].y,
    207         cubic2[2].x, cubic2[2].y, cubic2[3].x, cubic2[3].y));
    208 #endif
    209 #if ONE_OFF_DEBUG
    210     SkDebugf("computed quadratics set 1\n");
    211     for (int index = 0; index < quads1.count(); ++index) {
    212         const Quadratic& q = quads1[index];
    213         SkDebugf("  {{%1.9g,%1.9g}, {%1.9g,%1.9g}, {%1.9g,%1.9g}},\n", q[0].x, q[0].y,
    214                  q[1].x, q[1].y,  q[2].x, q[2].y);
    215     }
    216 #endif
    217     SkTDArray<Quadratic> quads2;
    218     cubic_to_quadratics(cubic2, calcPrecision(cubic2), quads2);
    219 #if ONE_OFF_DEBUG
    220     SkDebugf("computed quadratics set 2\n");
    221     for (int index = 0; index < quads2.count(); ++index) {
    222         const Quadratic& q = quads2[index];
    223         SkDebugf("  {{%1.9g,%1.9g}, {%1.9g,%1.9g}, {%1.9g,%1.9g}},\n", q[0].x, q[0].y,
    224                  q[1].x, q[1].y,  q[2].x, q[2].y);
    225     }
    226 #endif
    227     Intersections intersections2, intersections3;
    228     intersect2(cubic1, cubic2, intersections2);
    229     intersect3(cubic1, cubic2, intersections3);
    230     int pt1, pt2, pt3;
    231     bool found;
    232     double tt1, tt2, last = -1;
    233     _Point xy1, xy2;
    234     for (pt1 = 0; pt1 < intersections2.used(); ++pt1) {
    235         tt1 = intersections2.fT[0][pt1];
    236         SkASSERT(!approximately_equal(last, tt1));
    237         last = tt1;
    238         xy_at_t(cubic1, tt1, xy1.x, xy1.y);
    239         pt2 = intersections2.fFlip ? intersections2.used() - pt1 - 1 : pt1;
    240         tt2 = intersections2.fT[1][pt2];
    241         xy_at_t(cubic2, tt2, xy2.x, xy2.y);
    242 #if ONE_OFF_DEBUG
    243         SkDebugf("%s t1=%1.9g (%1.9g, %1.9g) (%1.9g, %1.9g) (%1.9g, %1.9g) t2=%1.9g\n",
    244                 __FUNCTION__, tt1, xy1.x, xy1.y, intersections2.fPt[pt1].x,
    245                 intersections2.fPt[pt1].y, xy2.x, xy2.y, tt2);
    246 #endif
    247         SkASSERT(xy1.approximatelyEqual(xy2));
    248 #ifdef SK_DEBUG
    249         found = false;
    250         for (pt3 = 0; pt3 < intersections3.used(); ++pt3) {
    251             if (roughly_equal(tt1, intersections3.fT[0][pt3])) {
    252                 found = true;
    253                 break;
    254             }
    255         }
    256         SkASSERT(found);
    257 #endif
    258     }
    259     last = -1;
    260     for (pt3 = 0; pt3 < intersections3.used(); ++pt3) {
    261         found = false;
    262         double tt3 = intersections3.fT[0][pt3];
    263         SkASSERT(!approximately_equal(last, tt3));
    264         last = tt3;
    265         for (pt1 = 0; pt1 < intersections2.used(); ++pt1) {
    266             if (approximately_equal(tt3, intersections2.fT[0][pt1])) {
    267                 found = true;
    268                 break;
    269             }
    270         }
    271         if (!found) {
    272             tt1 = intersections3.fT[0][pt3];
    273             xy_at_t(cubic1, tt1, xy1.x, xy1.y);
    274             pt2 = intersections3.fFlip ? intersections3.used() - pt3 - 1 : pt3;
    275             tt2 = intersections3.fT[1][pt2];
    276             xy_at_t(cubic2, tt2, xy2.x, xy2.y);
    277     #if ONE_OFF_DEBUG
    278             SkDebugf("%s t1=%1.9g (%1.9g, %1.9g) (%1.9g, %1.9g) (%1.9g, %1.9g) t2=%1.9g\n",
    279                     __FUNCTION__, tt1, xy1.x, xy1.y, intersections3.fPt[pt1].x,
    280                     intersections3.fPt[pt1].y, xy2.x, xy2.y, tt2);
    281     #endif
    282             SkASSERT(xy1.approximatelyEqual(xy2));
    283             SkDebugf("%s missing in intersect2\n", __FUNCTION__);
    284         }
    285     }
    286 }
    287 #endif
    288 
    289 static void oneOff3(const Cubic& cubic1, const Cubic& cubic2) {
    290 #if ONE_OFF_DEBUG
    291     SkDebugf("computed quadratics given\n");
    292     SkDebugf("  {{%1.9g,%1.9g}, {%1.9g,%1.9g}, {%1.9g,%1.9g}, {%1.9g,%1.9g}},\n",
    293         cubic1[0].x, cubic1[0].y, cubic1[1].x, cubic1[1].y,
    294         cubic1[2].x, cubic1[2].y, cubic1[3].x, cubic1[3].y);
    295     SkDebugf("  {{%1.9g,%1.9g}, {%1.9g,%1.9g}, {%1.9g,%1.9g}, {%1.9g,%1.9g}},\n",
    296         cubic2[0].x, cubic2[0].y, cubic2[1].x, cubic2[1].y,
    297         cubic2[2].x, cubic2[2].y, cubic2[3].x, cubic2[3].y);
    298 #endif
    299     SkTDArray<Quadratic> quads1;
    300     cubic_to_quadratics(cubic1, calcPrecision(cubic1), quads1);
    301 #if ONE_OFF_DEBUG
    302     SkDebugf("computed quadratics set 1\n");
    303     for (int index = 0; index < quads1.count(); ++index) {
    304         const Quadratic& q = quads1[index];
    305         SkDebugf("  {{%1.9g,%1.9g}, {%1.9g,%1.9g}, {%1.9g,%1.9g}},\n", q[0].x, q[0].y,
    306                  q[1].x, q[1].y,  q[2].x, q[2].y);
    307     }
    308 #endif
    309     SkTDArray<Quadratic> quads2;
    310     cubic_to_quadratics(cubic2, calcPrecision(cubic2), quads2);
    311 #if ONE_OFF_DEBUG
    312     SkDebugf("computed quadratics set 2\n");
    313     for (int index = 0; index < quads2.count(); ++index) {
    314         const Quadratic& q = quads2[index];
    315         SkDebugf("  {{%1.9g,%1.9g}, {%1.9g,%1.9g}, {%1.9g,%1.9g}},\n", q[0].x, q[0].y,
    316                  q[1].x, q[1].y,  q[2].x, q[2].y);
    317     }
    318 #endif
    319     Intersections intersections3;
    320     intersect3(cubic1, cubic2, intersections3);
    321     int pt2, pt3;
    322     double tt1, tt2, last = -1;
    323     _Point xy1, xy2;
    324     for (pt3 = 0; pt3 < intersections3.used(); ++pt3) {
    325         double tt3 = intersections3.fT[0][pt3];
    326      //   SkASSERT(!approximately_equal(last, tt3));
    327         last = tt3;
    328         tt1 = intersections3.fT[0][pt3];
    329         xy_at_t(cubic1, tt1, xy1.x, xy1.y);
    330         pt2 = intersections3.fFlip ? intersections3.used() - pt3 - 1 : pt3;
    331         tt2 = intersections3.fT[1][pt2];
    332         xy_at_t(cubic2, tt2, xy2.x, xy2.y);
    333 #if ONE_OFF_DEBUG
    334         SkDebugf("%s t1=%1.9g (%1.9g, %1.9g) (%1.9g, %1.9g) (%1.9g, %1.9g) t2=%1.9g\n",
    335                 __FUNCTION__, tt1, xy1.x, xy1.y, intersections3.fPt[pt3].x,
    336                 intersections3.fPt[pt3].y, xy2.x, xy2.y, tt2);
    337 #endif
    338         SkASSERT(xy1.approximatelyEqual(xy2));
    339     }
    340 }
    341 
    342 #if 0
    343 static int fails[][2] = {   {0, 23}, // fails in intersect2 recursing
    344                             {2, 7},  // answers differ, but neither is correct ('3' is closer)
    345                             {3, 26}, // fails in intersect2 recursing
    346                             {4, 9},  // fails in intersect2 recursing
    347                             {4, 10}, // fails in intersect2 recursing
    348                             {10, 17}, // fails in intersect2 recursing
    349                             {12, 14}, // loops indefinitely
    350                             {12, 21}, // fails in intersect2 recursing
    351                             {13, 21}, // fails in intersect2 recursing
    352                             {14, 21}, // fails in intersect2 recursing
    353                             {17, 25}, // fails in intersect2 recursing
    354                             {23, 25}, // fails in intersect2 recursing
    355 };
    356 
    357 static int failCount = sizeof(fails) / sizeof(fails[0]);
    358 #endif
    359 
    360 static void oneOff(int outer, int inner) {
    361     const Cubic& cubic1 = testSet[outer];
    362     const Cubic& cubic2 = testSet[inner];
    363 #if 0
    364     bool failing = false;
    365     for (int i = 0; i < failCount; ++i) {
    366         if ((fails[i][0] == outer && fails[i][1] == inner)
    367                 || (fails[i][1] == outer && fails[i][0] == inner)) {
    368             failing = true;
    369             break;
    370         }
    371     }
    372     if (!failing) {
    373         oneOff(cubic1, cubic2);
    374     } else {
    375 #endif
    376         oneOff3(cubic1, cubic2);
    377 //    }
    378 }
    379 
    380 void CubicIntersection_OneOffTest() {
    381     oneOff(0, 1);
    382 }
    383 
    384 static void newOneOff(int outer, int inner) {
    385     const Cubic& cubic1 = newTestSet[outer];
    386     const Cubic& cubic2 = newTestSet[inner];
    387     oneOff3(cubic1, cubic2);
    388 }
    389 
    390 void CubicIntersection_NewOneOffTest() {
    391     newOneOff(0, 1);
    392 }
    393 
    394 static void oneOffTests() {
    395     for (size_t outer = 0; outer < testSetCount - 1; ++outer) {
    396         for (size_t inner = outer + 1; inner < testSetCount; ++inner) {
    397             oneOff(outer, inner);
    398         }
    399     }
    400 }
    401 
    402 void CubicIntersection_OneOffTests() {
    403     oneOffTests();
    404 }
    405 
    406 #define DEBUG_CRASH 0
    407 
    408 class CubicChopper {
    409 public:
    410 
    411 // only finds one intersection
    412 CubicChopper(const Cubic& c1, const Cubic& c2)
    413     : cubic1(c1)
    414     , cubic2(c2)
    415     , depth(0) {
    416 }
    417 
    418 bool intersect(double minT1, double maxT1, double minT2, double maxT2) {
    419     Cubic sub1, sub2;
    420     // FIXME: carry last subdivide and reduceOrder result with cubic
    421     sub_divide(cubic1, minT1, maxT1, sub1);
    422     sub_divide(cubic2, minT2, maxT2, sub2);
    423     Intersections i;
    424     intersect3(sub1, sub2, i);
    425     if (i.used() == 0) {
    426         return false;
    427     }
    428     double x1, y1, x2, y2;
    429     t1 = minT1 + i.fT[0][0] * (maxT1 - minT1);
    430     t2 = minT2 + i.fT[1][0] * (maxT2 - minT2);
    431     xy_at_t(cubic1, t1, x1, y1);
    432     xy_at_t(cubic2, t2, x2, y2);
    433     if (AlmostEqualUlps(x1, x2) && AlmostEqualUlps(y1, y2)) {
    434         return true;
    435     }
    436     double half1 = (minT1 + maxT1) / 2;
    437     double half2 = (minT2 + maxT2) / 2;
    438     ++depth;
    439     bool result;
    440     if (depth & 1) {
    441         result = intersect(minT1, half1, minT2, maxT2) || intersect(half1, maxT1, minT2, maxT2)
    442             || intersect(minT1, maxT1, minT2, half2) || intersect(minT1, maxT1, half2, maxT2);
    443     } else {
    444         result = intersect(minT1, maxT1, minT2, half2) || intersect(minT1, maxT1, half2, maxT2)
    445             || intersect(minT1, half1, minT2, maxT2) || intersect(half1, maxT1, minT2, maxT2);
    446     }
    447     --depth;
    448     return result;
    449 }
    450 
    451 const Cubic& cubic1;
    452 const Cubic& cubic2;
    453 double t1;
    454 double t2;
    455 int depth;
    456 };
    457 
    458 #define TRY_OLD 0 // old way fails on test == 1
    459 
    460 void CubicIntersection_RandTestOld() {
    461     srand(0);
    462     const int tests = 1000000; // 10000000;
    463     double largestFactor = DBL_MAX;
    464     for (int test = 0; test < tests; ++test) {
    465         Cubic cubic1, cubic2;
    466         for (int i = 0; i < 4; ++i) {
    467             cubic1[i].x = (double) rand() / RAND_MAX * 100;
    468             cubic1[i].y = (double) rand() / RAND_MAX * 100;
    469             cubic2[i].x = (double) rand() / RAND_MAX * 100;
    470             cubic2[i].y = (double) rand() / RAND_MAX * 100;
    471         }
    472         if (test == 2513) { // the pair crosses three times, but the quadratic approximation
    473             continue; // only sees one -- should be OK to ignore the other two?
    474         }
    475         if (test == 12932) { // this exposes a weakness when one cubic touches the other but
    476             continue; // does not touch the quad approximation. Captured in qc.htm as cubic15
    477         }
    478     #if DEBUG_CRASH
    479         char str[1024];
    480         sprintf(str, "{{%1.9g, %1.9g}, {%1.9g, %1.9g}, {%1.9g, %1.9g}, {%1.9g, %1.9g}},\n"
    481             "{{%1.9g, %1.9g}, {%1.9g, %1.9g}, {%1.9g, %1.9g}, {%1.9g, %1.9g}},\n",
    482                 cubic1[0].x, cubic1[0].y,  cubic1[1].x, cubic1[1].y, cubic1[2].x, cubic1[2].y,
    483                 cubic1[3].x, cubic1[3].y,
    484                 cubic2[0].x, cubic2[0].y,  cubic2[1].x, cubic2[1].y, cubic2[2].x, cubic2[2].y,
    485                 cubic2[3].x, cubic2[3].y);
    486     #endif
    487         _Rect rect1, rect2;
    488         rect1.setBounds(cubic1);
    489         rect2.setBounds(cubic2);
    490         bool boundsIntersect = rect1.left <= rect2.right && rect2.left <= rect2.right
    491                 && rect1.top <= rect2.bottom && rect2.top <= rect1.bottom;
    492         Intersections i1, i2;
    493     #if TRY_OLD
    494         bool oldIntersects = intersect(cubic1, cubic2, i1);
    495     #else
    496         bool oldIntersects = false;
    497     #endif
    498         if (test == -1) {
    499             SkDebugf("ready...\n");
    500         }
    501         bool newIntersects = intersect3(cubic1, cubic2, i2);
    502         if (!boundsIntersect && (oldIntersects || newIntersects)) {
    503     #if DEBUG_CRASH
    504             SkDebugf("%s %d unexpected intersection boundsIntersect=%d oldIntersects=%d"
    505                     " newIntersects=%d\n%s %s\n", __FUNCTION__, test, boundsIntersect,
    506                     oldIntersects, newIntersects, __FUNCTION__, str);
    507     #endif
    508             SkASSERT(0);
    509         }
    510         if (oldIntersects && !newIntersects) {
    511     #if DEBUG_CRASH
    512             SkDebugf("%s %d missing intersection oldIntersects=%d newIntersects=%d\n%s %s\n",
    513                     __FUNCTION__, test, oldIntersects, newIntersects, __FUNCTION__, str);
    514     #endif
    515             SkASSERT(0);
    516         }
    517         if (!oldIntersects && !newIntersects) {
    518             continue;
    519         }
    520         if (i2.used() > 1) {
    521             continue;
    522             // just look at single intercepts for simplicity
    523         }
    524         Intersections self1, self2; // self-intersect checks
    525         if (intersect(cubic1, self1)) {
    526             continue;
    527         }
    528         if (intersect(cubic2, self2)) {
    529             continue;
    530         }
    531         // binary search for range necessary to enclose real intersection
    532         CubicChopper c(cubic1, cubic2);
    533         bool result = c.intersect(0, 1, 0, 1);
    534         if (!result) {
    535             // FIXME: a failure here probably means that a core routine used by CubicChopper is failing
    536             continue;
    537         }
    538         double delta1 = fabs(c.t1 - i2.fT[0][0]);
    539         double delta2 = fabs(c.t2 - i2.fT[1][0]);
    540         double calc1 = calcPrecision(cubic1);
    541         double calc2 = calcPrecision(cubic2);
    542         double factor1 = calc1 / delta1;
    543         double factor2 = calc2 / delta2;
    544         SkDebugf("%s %d calc1=%1.9g delta1=%1.9g factor1=%1.9g calc2=%1.9g delta2=%1.9g"
    545                 " factor2=%1.9g\n", __FUNCTION__, test,
    546                 calc1, delta1, factor1, calc2, delta2, factor2);
    547         if (factor1 < largestFactor) {
    548             SkDebugf("WE HAVE A WINNER! %1.9g\n", factor1);
    549     #if DEBUG_CRASH
    550             SkDebugf("%s\n", str);
    551     #endif
    552             oneOff3(cubic1, cubic2);
    553             largestFactor = factor1;
    554         }
    555         if (factor2 < largestFactor) {
    556             SkDebugf("WE HAVE A WINNER! %1.9g\n", factor2);
    557     #if DEBUG_CRASH
    558             SkDebugf("%s\n", str);
    559     #endif
    560             oneOff3(cubic1, cubic2);
    561             largestFactor = factor2;
    562         }
    563     }
    564 }
    565 
    566 void CubicIntersection_RandTest() {
    567     srand(0);
    568     const int tests = 10000000;
    569     for (int test = 0; test < tests; ++test) {
    570         Cubic cubic1, cubic2;
    571         for (int i = 0; i < 4; ++i) {
    572             cubic1[i].x = (double) rand() / RAND_MAX * 100;
    573             cubic1[i].y = (double) rand() / RAND_MAX * 100;
    574             cubic2[i].x = (double) rand() / RAND_MAX * 100;
    575             cubic2[i].y = (double) rand() / RAND_MAX * 100;
    576         }
    577     #if DEBUG_CRASH
    578         char str[1024];
    579         sprintf(str, "{{%1.9g, %1.9g}, {%1.9g, %1.9g}, {%1.9g, %1.9g}, {%1.9g, %1.9g}},\n"
    580             "{{%1.9g, %1.9g}, {%1.9g, %1.9g}, {%1.9g, %1.9g}, {%1.9g, %1.9g}},\n",
    581                 cubic1[0].x, cubic1[0].y,  cubic1[1].x, cubic1[1].y, cubic1[2].x, cubic1[2].y,
    582                 cubic1[3].x, cubic1[3].y,
    583                 cubic2[0].x, cubic2[0].y,  cubic2[1].x, cubic2[1].y, cubic2[2].x, cubic2[2].y,
    584                 cubic2[3].x, cubic2[3].y);
    585     #endif
    586         _Rect rect1, rect2;
    587         rect1.setBounds(cubic1);
    588         rect2.setBounds(cubic2);
    589         bool boundsIntersect = rect1.left <= rect2.right && rect2.left <= rect2.right
    590                 && rect1.top <= rect2.bottom && rect2.top <= rect1.bottom;
    591         if (test == -1) {
    592             SkDebugf("ready...\n");
    593         }
    594         Intersections intersections2;
    595         bool newIntersects = intersect3(cubic1, cubic2, intersections2);
    596         if (!boundsIntersect && newIntersects) {
    597     #if DEBUG_CRASH
    598             SkDebugf("%s %d unexpected intersection boundsIntersect=%d "
    599                     " newIntersects=%d\n%s %s\n", __FUNCTION__, test, boundsIntersect,
    600                     newIntersects, __FUNCTION__, str);
    601     #endif
    602             SkASSERT(0);
    603         }
    604         for (int pt = 0; pt < intersections2.used(); ++pt) {
    605             double tt1 = intersections2.fT[0][pt];
    606             _Point xy1, xy2;
    607             xy_at_t(cubic1, tt1, xy1.x, xy1.y);
    608             int pt2 = intersections2.fFlip ? intersections2.used() - pt - 1 : pt;
    609             double tt2 = intersections2.fT[1][pt2];
    610             xy_at_t(cubic2, tt2, xy2.x, xy2.y);
    611         #if 0
    612             SkDebugf("%s t1=%1.9g (%1.9g, %1.9g) (%1.9g, %1.9g) t2=%1.9g\n", __FUNCTION__,
    613                 tt1, xy1.x, xy1.y, xy2.x, xy2.y, tt2);
    614         #endif
    615             SkASSERT(xy1.approximatelyEqual(xy2));
    616         }
    617     }
    618 }
    619 
    620 static void intersectionFinder(int index0, int index1, double t1Seed, double t2Seed,
    621         double t1Step, double t2Step) {
    622     const Cubic& cubic1 = newTestSet[index0];
    623     const Cubic& cubic2 = newTestSet[index1];
    624     _Point t1[3], t2[3];
    625     bool toggle = true;
    626     do {
    627         xy_at_t(cubic1, t1Seed - t1Step, t1[0].x, t1[0].y);
    628         xy_at_t(cubic1, t1Seed,          t1[1].x, t1[1].y);
    629         xy_at_t(cubic1, t1Seed + t1Step, t1[2].x, t1[2].y);
    630         xy_at_t(cubic2, t2Seed - t2Step, t2[0].x, t2[0].y);
    631         xy_at_t(cubic2, t2Seed,          t2[1].x, t2[1].y);
    632         xy_at_t(cubic2, t2Seed + t2Step, t2[2].x, t2[2].y);
    633         double dist[3][3];
    634         dist[1][1] = t1[1].distance(t2[1]);
    635         int best_i = 1, best_j = 1;
    636         for (int i = 0; i < 3; ++i) {
    637             for (int j = 0; j < 3; ++j) {
    638                 if (i == 1 && j == 1) {
    639                     continue;
    640                 }
    641                 dist[i][j] = t1[i].distance(t2[j]);
    642                 if (dist[best_i][best_j] > dist[i][j]) {
    643                     best_i = i;
    644                     best_j = j;
    645                 }
    646             }
    647         }
    648         if (best_i == 0) {
    649             t1Seed -= t1Step;
    650         } else if (best_i == 2) {
    651             t1Seed += t1Step;
    652         }
    653         if (best_j == 0) {
    654             t2Seed -= t2Step;
    655         } else if (best_j == 2) {
    656             t2Seed += t2Step;
    657         }
    658         if (best_i == 1 && best_j == 1) {
    659             if ((toggle ^= true)) {
    660                 t1Step /= 2;
    661             } else {
    662                 t2Step /= 2;
    663             }
    664         }
    665     } while (!t1[1].approximatelyEqual(t2[1]));
    666     t1Step = t2Step = 0.1;
    667     double t10 = t1Seed - t1Step * 2;
    668     double t12 = t1Seed + t1Step * 2;
    669     double t20 = t2Seed - t2Step * 2;
    670     double t22 = t2Seed + t2Step * 2;
    671     _Point test;
    672     while (!approximately_zero(t1Step)) {
    673         xy_at_t(cubic1, t10, test.x, test.y);
    674         t10 += t1[1].approximatelyEqual(test) ? -t1Step : t1Step;
    675         t1Step /= 2;
    676     }
    677     t1Step = 0.1;
    678     while (!approximately_zero(t1Step)) {
    679         xy_at_t(cubic1, t12, test.x, test.y);
    680         t12 -= t1[1].approximatelyEqual(test) ? -t1Step : t1Step;
    681         t1Step /= 2;
    682     }
    683     while (!approximately_zero(t2Step)) {
    684         xy_at_t(cubic2, t20, test.x, test.y);
    685         t20 += t2[1].approximatelyEqual(test) ? -t2Step : t2Step;
    686         t2Step /= 2;
    687     }
    688     t2Step = 0.1;
    689     while (!approximately_zero(t2Step)) {
    690         xy_at_t(cubic2, t22, test.x, test.y);
    691         t22 -= t2[1].approximatelyEqual(test) ? -t2Step : t2Step;
    692         t2Step /= 2;
    693     }
    694 #if ONE_OFF_DEBUG
    695     SkDebugf("%s t1=(%1.9g<%1.9g<%1.9g) t2=(%1.9g<%1.9g<%1.9g)\n", __FUNCTION__,
    696         t10, t1Seed, t12, t20, t2Seed, t22);
    697     _Point p10 = xy_at_t(cubic1, t10);
    698     _Point p1Seed = xy_at_t(cubic1, t1Seed);
    699     _Point p12 = xy_at_t(cubic1, t12);
    700     SkDebugf("%s p1=(%1.9g,%1.9g)<(%1.9g,%1.9g)<(%1.9g,%1.9g)\n", __FUNCTION__,
    701         p10.x, p10.y, p1Seed.x, p1Seed.y, p12.x, p12.y);
    702     _Point p20 = xy_at_t(cubic2, t20);
    703     _Point p2Seed = xy_at_t(cubic2, t2Seed);
    704     _Point p22 = xy_at_t(cubic2, t22);
    705     SkDebugf("%s p2=(%1.9g,%1.9g)<(%1.9g,%1.9g)<(%1.9g,%1.9g)\n", __FUNCTION__,
    706         p20.x, p20.y, p2Seed.x, p2Seed.y, p22.x, p22.y);
    707 #endif
    708 }
    709 
    710 void CubicIntersection_IntersectionFinder() {
    711 
    712  //   double t1Seed = 0.87;
    713  //   double t2Seed = 0.87;
    714     double t1Step = 0.000001;
    715     double t2Step = 0.000001;
    716     intersectionFinder(0, 1, 0.855895664, 0.864850875, t1Step, t2Step);
    717     intersectionFinder(0, 1, 0.865207906, 0.865207887, t1Step, t2Step);
    718     intersectionFinder(0, 1, 0.865213351, 0.865208087, t1Step, t2Step);
    719 }
    720 
    721 static void coincidentTest() {
    722 #if 0
    723     Cubic cubic1 = {{0, 1}, {0, 2}, {1, 0}, {1, 0}};
    724     Cubic cubic2 = {{0, 1}, {0, 2}, {1, 0}, {6, 1}};
    725 #endif
    726 }
    727 
    728 void CubicIntersection_SelfTest() {
    729     const Cubic selfSet[] = {
    730         {{0,2}, {2,3}, {5,1}, {3,2}},
    731         {{0,2}, {3,5}, {5,0}, {4,2}},
    732         {{3.34,8.98}, {1.95,10.27}, {3.76,7.65}, {4.96,10.64}},
    733         {{3.13,2.74}, {1.08,4.62}, {3.71,0.94}, {2.01,3.81}},
    734         {{6.71,3.14}, {7.99,2.75}, {8.27,1.96}, {6.35,3.57}},
    735         {{12.81,7.27}, {7.22,6.98}, {12.49,8.97}, {11.42,6.18}},
    736     };
    737     size_t selfSetCount = sizeof(selfSet) / sizeof(selfSet[0]);
    738     size_t firstFail = 1;
    739     for (size_t index = firstFail; index < selfSetCount; ++index) {
    740         const Cubic& cubic = selfSet[index];
    741     #if ONE_OFF_DEBUG
    742         int idx2;
    743         double max[3];
    744         int ts = find_cubic_max_curvature(cubic, max);
    745         for (idx2 = 0; idx2 < ts; ++idx2) {
    746             SkDebugf("%s max[%d]=%1.9g (%1.9g, %1.9g)\n", __FUNCTION__, idx2,
    747                     max[idx2], xy_at_t(cubic, max[idx2]).x, xy_at_t(cubic, max[idx2]).y);
    748         }
    749         SkTDArray<double> ts1;
    750         SkTDArray<Quadratic> quads1;
    751         cubic_to_quadratics(cubic, calcPrecision(cubic), ts1);
    752         for (idx2 = 0; idx2 < ts1.count(); ++idx2) {
    753             SkDebugf("%s t[%d]=%1.9g\n", __FUNCTION__, idx2, ts1[idx2]);
    754         }
    755         cubic_to_quadratics(cubic, calcPrecision(cubic), quads1);
    756         for (idx2 = 0; idx2 < quads1.count(); ++idx2) {
    757             const Quadratic& q = quads1[idx2];
    758             SkDebugf("  {{%1.9g,%1.9g}, {%1.9g,%1.9g}, {%1.9g,%1.9g}},\n",
    759                     q[0].x, q[0].y,  q[1].x, q[1].y,  q[2].x, q[2].y);
    760         }
    761         SkDebugf("\n");
    762     #endif
    763         Intersections i;
    764         SkDEBUGCODE(int result = ) intersect(cubic, i);
    765         SkASSERT(result == 1);
    766         SkASSERT(i.used() == 1);
    767         SkASSERT(!approximately_equal(i.fT[0][0], i.fT[1][0]));
    768         _Point pt1 = xy_at_t(cubic, i.fT[0][0]);
    769         _Point pt2 = xy_at_t(cubic, i.fT[1][0]);
    770         SkASSERT(pt1.approximatelyEqual(pt2));
    771     }
    772 }
    773 
    774 void CubicIntersection_Test() {
    775     oneOffTests();
    776     coincidentTest();
    777     standardTestCases();
    778 }
    779