gfx/skia/trunk/src/pathops/SkPathOpsTriangle.cpp@6474c204b198 (annotated)
gfx/skia/trunk/src/pathops/SkPathOpsTriangle.cpp
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
| michael@0 | 1 | /* |
| michael@0 | 2 | * Copyright 2012 Google Inc. |
| michael@0 | 3 | * |
| michael@0 | 4 | * Use of this source code is governed by a BSD-style license that can be |
| michael@0 | 5 | * found in the LICENSE file. |
| michael@0 | 6 | */ |
| michael@0 | 7 | |
| michael@0 | 8 | #include "SkPathOpsTriangle.h" |
| michael@0 | 9 | |
| michael@0 | 10 | // http://www.blackpawn.com/texts/pointinpoly/default.html |
| michael@0 | 11 | // return true if pt is inside triangle; false if outside or on the line |
| michael@0 | 12 | bool SkDTriangle::contains(const SkDPoint& pt) const { |
| michael@0 | 13 | // Compute vectors |
| michael@0 | 14 | SkDVector v0 = fPts[2] - fPts[0]; |
| michael@0 | 15 | SkDVector v1 = fPts[1] - fPts[0]; |
| michael@0 | 16 | SkDVector v2 = pt - fPts[0]; |
| michael@0 | 17 | |
| michael@0 | 18 | // Compute dot products |
| michael@0 | 19 | double dot00 = v0.dot(v0); |
| michael@0 | 20 | double dot01 = v0.dot(v1); |
| michael@0 | 21 | double dot02 = v0.dot(v2); |
| michael@0 | 22 | double dot11 = v1.dot(v1); |
| michael@0 | 23 | double dot12 = v1.dot(v2); |
| michael@0 | 24 | |
| michael@0 | 25 | // original code doesn't handle degenerate input; isn't symmetric with inclusion of corner pts; |
| michael@0 | 26 | // introduces necessary error with divide; doesn't short circuit on early answer |
| michael@0 | 27 | #if 0 |
| michael@0 | 28 | // Compute barycentric coordinates |
| michael@0 | 29 | double invDenom = 1 / (dot00 * dot11 - dot01 * dot01); |
| michael@0 | 30 | double u = (dot11 * dot02 - dot01 * dot12) * invDenom; |
| michael@0 | 31 | double v = (dot00 * dot12 - dot01 * dot02) * invDenom; |
| michael@0 | 32 | |
| michael@0 | 33 | // Check if point is in triangle |
| michael@0 | 34 | return (u >= 0) && (v >= 0) && (u + v <= 1); |
| michael@0 | 35 | #else |
| michael@0 | 36 | double w = dot00 * dot11 - dot01 * dot01; |
| michael@0 | 37 | if (w == 0) { |
| michael@0 | 38 | return false; |
| michael@0 | 39 | } |
| michael@0 | 40 | double wSign = w < 0 ? -1 : 1; |
| michael@0 | 41 | double u = (dot11 * dot02 - dot01 * dot12) * wSign; |
| michael@0 | 42 | if (u <= 0) { |
| michael@0 | 43 | return false; |
| michael@0 | 44 | } |
| michael@0 | 45 | double v = (dot00 * dot12 - dot01 * dot02) * wSign; |
| michael@0 | 46 | if (v <= 0) { |
| michael@0 | 47 | return false; |
| michael@0 | 48 | } |
| michael@0 | 49 | return u + v < w * wSign; |
| michael@0 | 50 | #endif |
| michael@0 | 51 | } |
