pathops version two

src/pathops/SkDLineIntersection.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkIntersections.h"
 #include "SkPathOpsLine.h"
 
-/* Determine the intersection point of two lines. This assumes the lines are not parallel,
-   and that that the lines are infinite.
-   From http://en.wikipedia.org/wiki/Line-line_intersection
- */
-SkDPoint SkIntersections::Line(const SkDLine& a, const SkDLine& b) {
-    double axLen = a[1].fX - a[0].fX;
-    double ayLen = a[1].fY - a[0].fY;
-    double bxLen = b[1].fX - b[0].fX;
-    double byLen = b[1].fY - b[0].fY;
-    double denom = byLen * axLen - ayLen * bxLen;
-    SkASSERT(denom);
-    double term1 = a[1].fX * a[0].fY - a[1].fY * a[0].fX;
-    double term2 = b[1].fX * b[0].fY - b[1].fY * b[0].fX;
-    SkDPoint p;
-    p.fX = (term1 * bxLen - axLen * term2) / denom;
-    p.fY = (term1 * byLen - ayLen * term2) / denom;
-    return p;
-}
-
-int SkIntersections::cleanUpCoincidence() {
-    do {
-        int last = fUsed - 1;
-        for (int index = 0; index < last; ++index) {
-            if (fT[0][index] == fT[0][index + 1]) {
-                removeOne(index + (int) (fT[1][index] == 0 || fT[1][index] == 1));
-                goto tryAgain;
-            }
-        }
-        for (int index = 0; index < last; ++index) {
-            if (fT[1][index] == fT[1][index + 1]) {
-                removeOne(index + (int) (fT[0][index] == 0 || fT[0][index] == 1));
-                goto tryAgain;
-            }
-        }
-        return fUsed;
-tryAgain: ;
-    } while (true);
-}
-
 void SkIntersections::cleanUpParallelLines(bool parallel) {
     while (fUsed > 2) {
         removeOne(1);
     }
     if (fUsed == 2 && !parallel) {
         bool startMatch = fT[0][0] == 0 || fT[1][0] == 0 || fT[1][0] == 1;
         bool endMatch = fT[0][1] == 1 || fT[1][1] == 0 || fT[1][1] == 1;
         if ((!startMatch && !endMatch) || approximately_equal(fT[0][0], fT[0][1])) {
             SkASSERT(startMatch || endMatch);
             removeOne(endMatch);
         }
     }
+    if (fUsed == 2) {
+        fIsCoincident[0] = fIsCoincident[1] = 0x03;
+    }
 }
 
 void SkIntersections::computePoints(const SkDLine& line, int used) {
     fPt[0] = line.ptAtT(fT[0][0]);
     if ((fUsed = used) == 2) {
         fPt[1] = line.ptAtT(fT[0][1]);
     }
 }
 
 int SkIntersections::intersectRay(const SkDLine& a, const SkDLine& b) {
     fMax = 2;
     SkDVector aLen = a[1] - a[0];
     SkDVector bLen = b[1] - b[0];
     /* Slopes match when denom goes to zero:
                       axLen / ayLen ==                   bxLen / byLen
     (ayLen * byLen) * axLen / ayLen == (ayLen * byLen) * bxLen / byLen
              byLen  * axLen         ==  ayLen          * bxLen
              byLen  * axLen         -   ayLen          * bxLen == 0 ( == denom )
      */
     double denom = bLen.fY * aLen.fX - aLen.fY * bLen.fX;
     SkDVector ab0 = a[0] - b[0];
     double numerA = ab0.fY * bLen.fX - bLen.fY * ab0.fX;
     double numerB = ab0.fY * aLen.fX - aLen.fY * ab0.fX;
-#if 0
-    if (!between(0, numerA, denom) || !between(0, numerB, denom)) {
-        fUsed = 0;
-        return 0;
-    }
-#endif
     numerA /= denom;
     numerB /= denom;
     int used;
     if (!approximately_zero(denom)) {
         fT[0][0] = numerA;
         fT[1][0] = numerB;
         used = 1;
     } else {
        /* See if the axis intercepts match:
                   ay - ax * ayLen / axLen  ==          by - bx * ayLen / axLen
@@ skipping 83 matching lines @@
                 for (int iA = 0; iA < 2; ++iA) {
                     if (!aNotB[iA]) {
                         continue;
                     }
                     int nearer = aNearB[iA] > 0.5;
                     if (!bNotA[nearer]) {
                         continue;
                     }
                     SkASSERT(a[iA] != b[nearer]);
                     SkASSERT(iA == (bNearA[nearer] > 0.5));
-                    fNearlySame[iA] = true;
                     insertNear(iA, nearer, a[iA], b[nearer]);
                     aNearB[iA] = -1;
                     bNearA[nearer] = -1;
                     nearCount -= 2;
                 }
             }
             if (nearCount > 0) {
                 for (int iA = 0; iA < 2; ++iA) {
                     if (aNearB[iA] >= 0) {
                         insert(iA, aNearB[iA], a[iA]);
@@ skipping 24 matching lines @@
     if (AlmostEqualUlps(min, max) && max - min < fabs(line[0].fX - line[1].fX)) {
         return 2;
     }
     return 1;
 }
 
 static double horizontal_intercept(const SkDLine& line, double y) {
      return SkPinT((y - line[0].fY) / (line[1].fY - line[0].fY));
 }
 
-int SkIntersections::horizontal(const SkDLine& line, double y) {
-    fMax = 2;
-    int horizontalType = horizontal_coincident(line, y);
-    if (horizontalType == 1) {
-        fT[0][0] = horizontal_intercept(line, y);
-    } else if (horizontalType == 2) {
-        fT[0][0] = 0;
-        fT[0][1] = 1;
-    }
-    return fUsed = horizontalType;
-}
-
 int SkIntersections::horizontal(const SkDLine& line, double left, double right,
                                 double y, bool flipped) {
     fMax = 3;  // clean up parallel at the end will limit the result to 2 at the most
     // see if end points intersect the opposite line
     double t;
     const SkDPoint leftPt = { left, y };
     if ((t = line.exactPoint(leftPt)) >= 0) {
         insert(t, (double) flipped, leftPt);
     }
     if (left != right) {
@@ skipping 56 matching lines @@
     if (AlmostEqualUlps(min, max)) {
         return 2;
     }
     return 1;
 }
 
 static double vertical_intercept(const SkDLine& line, double x) {
     return SkPinT((x - line[0].fX) / (line[1].fX - line[0].fX));
 }
 
-int SkIntersections::vertical(const SkDLine& line, double x) {
-    fMax = 2;
-    int verticalType = vertical_coincident(line, x);
-    if (verticalType == 1) {
-        fT[0][0] = vertical_intercept(line, x);
-    } else if (verticalType == 2) {
-        fT[0][0] = 0;
-        fT[0][1] = 1;
-    }
-    return fUsed = verticalType;
-}
-
 int SkIntersections::vertical(const SkDLine& line, double top, double bottom,
                               double x, bool flipped) {
     fMax = 3;  // cleanup parallel lines will bring this back line
     // see if end points intersect the opposite line
     double t;
     SkDPoint topPt = { x, top };
     if ((t = line.exactPoint(topPt)) >= 0) {
         insert(t, (double) flipped, topPt);
     }
     if (top != bottom) {
@@ skipping 38 matching lines @@
                     insert((double) index, flipped ? 1 - t : t, line[index]);
                 }
             }
         }
     }
     cleanUpParallelLines(result == 2);
     SkASSERT(fUsed <= 2);
     return fUsed;
 }
 
-// from http://www.bryceboe.com/wordpress/wp-content/uploads/2006/10/intersect.py
-// 4 subs, 2 muls, 1 cmp
-static bool ccw(const SkDPoint& A, const SkDPoint& B, const SkDPoint& C) {
-    return (C.fY - A.fY) * (B.fX - A.fX) > (B.fY - A.fY) * (C.fX - A.fX);
-}
-
-// 16 subs, 8 muls, 6 cmps
-bool SkIntersections::Test(const SkDLine& a, const SkDLine& b) {
-    return ccw(a[0], b[0], b[1]) != ccw(a[1], b[0], b[1])
-            && ccw(a[0], a[1], b[0]) != ccw(a[0], a[1], b[1]);
-}