Index: ui/gfx/geometry/quad_f.cc |
diff --git a/ui/gfx/geometry/quad_f.cc b/ui/gfx/geometry/quad_f.cc |
index 1283b0dc3bbc4a1a64542840945d1f8c360d83f1..dbc50458b3fa1e04aedfdee3c51d5ae00351b46a 100644 |
--- a/ui/gfx/geometry/quad_f.cc |
+++ b/ui/gfx/geometry/quad_f.cc |
@@ -62,28 +62,24 @@ static inline bool PointIsInTriangle(const PointF& point, |
const PointF& r1, |
const PointF& r2, |
const PointF& r3) { |
- // Compute the barycentric coordinates of |point| relative to the triangle |
- // (r1, r2, r3). This algorithm comes from Christer Ericson's Real-Time |
- // Collision Detection. |
- Vector2dF v0 = r2 - r1; |
- Vector2dF v1 = r3 - r1; |
- Vector2dF v2 = point - r1; |
+ // Compute the barycentric coordinates (u, v, w) of |point| relative to the |
+ // triangle (r1, r2, r3) by the solving the system of equations: |
+ // 1) point = u * r1 + v * r2 + w * r3 |
+ // 2) u + v + w = 1 |
+ // This algorithm comes from Christer Ericson's Real-Time Collision Detection. |
- double dot00 = DotProduct(v0, v0); |
- double dot01 = DotProduct(v0, v1); |
- double dot11 = DotProduct(v1, v1); |
- double dot20 = DotProduct(v2, v0); |
- double dot21 = DotProduct(v2, v1); |
+ Vector2dF r31 = r1 - r3; |
+ Vector2dF r32 = r2 - r3; |
+ Vector2dF r3p = point - r3; |
- double denom = dot00 * dot11 - dot01 * dot01; |
- |
- double v = (dot11 * dot20 - dot01 * dot21) / denom; |
- double w = (dot00 * dot21 - dot01 * dot20) / denom; |
- double u = 1 - v - w; |
+ float denom = r32.y() * r31.x() - r32.x() * r31.y(); |
+ float u = (r32.y() * r3p.x() - r32.x() * r3p.y()) / denom; |
+ float v = (r31.x() * r3p.y() - r31.y() * r3p.x()) / denom; |
+ float w = 1.f - u - v; |
// Use the barycentric coordinates to test if |point| is inside the |
// triangle (r1, r2, r2). |
- return (v >= 0) && (w >= 0) && (u >= 0); |
+ return (u >= 0) && (v >= 0) && (w >= 0); |
} |
bool QuadF::Contains(const PointF& point) const { |