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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 "TriangleUtilities.h" | |
9 | |
10 // http://www.blackpawn.com/texts/pointinpoly/default.html | |
11 bool pointInTriangle(const Triangle& triangle, const _Point& pt) { | |
12 // Compute vectors | |
13 _Vector v0 = triangle[2] - triangle[0]; | |
14 _Vector v1 = triangle[1] - triangle[0]; | |
15 _Vector v2 = pt - triangle[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 } | |
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