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 8 #include "SkPathOpsTriangle.h" 9 10 // http://www.blackpawn.com/texts/pointinpoly/default.html 11 bool SkDTriangle::contains(const SkDPoint& pt) const { 12 // Compute vectors 13 SkDVector v0 = fPts[2] - fPts[0]; 14 SkDVector v1 = fPts[1] - fPts[0]; 15 SkDVector v2 = pt - fPts[0]; 16 17 // Compute dot products 18 double dot00 = v0.dot(v0); 19 double dot01 = v0.dot(v1); 20 double dot02 = v0.dot(v2); 21 double dot11 = v1.dot(v1); 22 double dot12 = v1.dot(v2); 23 24 // Compute barycentric coordinates 25 double invDenom = 1 / (dot00 * dot11 - dot01 * dot01); 26 double u = (dot11 * dot02 - dot01 * dot12) * invDenom; 27 double v = (dot00 * dot12 - dot01 * dot02) * invDenom; 28 29 // Check if point is in triangle 30 return (u >= 0) && (v >= 0) && (u + v < 1); 31 } 32
