The Tor Browser: gfx/skia/trunk/src/pathops/SkPathOpsTriangle.cpp@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     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  */

     8 #include "SkPathOpsTriangle.h"

    10 // http://www.blackpawn.com/texts/pointinpoly/default.html

    11 // return true if pt is inside triangle; false if outside or on the line

    12 bool SkDTriangle::contains(const SkDPoint& pt) const {

    13 // Compute vectors

    14     SkDVector v0 = fPts[2] - fPts[0];

    15     SkDVector v1 = fPts[1] - fPts[0];

    16     SkDVector v2 = pt - fPts[0];

    18 // Compute dot products

    19     double dot00 = v0.dot(v0);

    20     double dot01 = v0.dot(v1);

    21     double dot02 = v0.dot(v2);

    22     double dot11 = v1.dot(v1);

    23     double dot12 = v1.dot(v2);

    25 // original code doesn't handle degenerate input; isn't symmetric with inclusion of corner pts;

    26 // introduces necessary error with divide; doesn't short circuit on early answer

    27 #if 0

    28 // Compute barycentric coordinates

    29     double invDenom = 1 / (dot00 * dot11 - dot01 * dot01);

    30     double u = (dot11 * dot02 - dot01 * dot12) * invDenom;

    31     double v = (dot00 * dot12 - dot01 * dot02) * invDenom;

    33 // Check if point is in triangle

    34     return (u >= 0) && (v >= 0) && (u + v <= 1);

    35 #else

    36     double w = dot00 * dot11 - dot01 * dot01;

    37     if (w == 0) {

    38         return false;

    39     }

    40     double wSign = w < 0 ? -1 : 1;

    41     double u = (dot11 * dot02 - dot01 * dot12) * wSign;

    42     if (u <= 0) {

    43         return false;

    44     }

    45     double v = (dot00 * dot12 - dot01 * dot02) * wSign;

    46     if (v <= 0) {

    47         return false;

    48     }

    49     return u + v < w * wSign;

    50 #endif

    51 }

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