| static private IsPointInTriangle ( Point p, Point t0, Point t1, Point t2 ) : bool | ||
| p | Point | Point to locate. |
| t0 | Point | Corner point of triangle. |
| t1 | Point | Corner point of triangle. |
| t2 | Point | Corner point of triangle. |
| return | bool | |
internal static bool IsPointInTriangle(Point p, Point t0, Point t1, Point t2)
{
// TODO: no need to create new Point instances here
Point d0 = new Point(t1.X - t0.X, t1.Y - t0.Y);
Point d1 = new Point(t2.X - t0.X, t2.Y - t0.Y);
Point d2 = new Point(p.X - t0.X, p.Y - t0.Y);
// crossproduct of (0, 0, 1) and d0
Point c0 = new Point(-d0.Y, d0.X);
// crossproduct of (0, 0, 1) and d1
Point c1 = new Point(-d1.Y, d1.X);
// Linear combination d2 = s * d0 + v * d1.
//
// Multiply both sides of the equation with c0 and c1
// and solve for s and v respectively
//
// s = d2 * c1 / d0 * c1
// v = d2 * c0 / d1 * c0
double s = DotProduct(d2, c1) / DotProduct(d0, c1);
double v = DotProduct(d2, c0) / DotProduct(d1, c0);
if (s >= 0 && v >= 0 && ((s + v) <= 1))
{
// Point is inside or on the edge of this triangle.
return true;
}
return false;
}
public ITriangle Query(double x, double y)
{
Point point = new Point(x, y);
List <int> nums = this.root.FindTriangles(point);
List <ITriangle> triangles = new List <ITriangle>();
foreach (int num in nums)
{
ITriangle triangle = this.triangles[num];
if (!QuadTree.IsPointInTriangle(point, triangle.GetVertex(0), triangle.GetVertex(1), triangle.GetVertex(2)))
{
continue;
}
triangles.Add(triangle);
}
return(triangles.FirstOrDefault <ITriangle>());
}
