/// <summary>
/// Tests for intersection between a <see cref="Ray"/> and a <see cref="Triangle"/>.
/// </summary>
/// <param name="ray">A <see cref="Ray"/> instance.</param>
/// <param name="triangle">A <see cref="Triangle"/> instance.</param>
/// <returns>An <see cref="IntersectionPair"/> instance containing the intersection information.</returns>
/// <remarks>
/// For information about the algorithm visit http://www.acm.org/jgt/papers/MollerTrumbore97/
/// </remarks>
public static IntersectionPair Intersects(Ray ray, Triangle triangle)
{
// Find the vectors for the 2 edges sharing trangle.Point0
Vector3F edge1 = triangle.Point1 - triangle.Point0;
Vector3F edge2 = triangle.Point2 - triangle.Point0;
// Begin calculating determinant - also used to calc the U parameter.
Vector3F pvec = Vector3F.CrossProduct(ray.Direction, edge2);
float det = Vector3F.Dot(edge1, pvec);
// If determinant is zero the ray lies in plane of the triangle
if (MathFunctions.ApproxEquals(det, 0.0f))
{
return new IntersectionPair(false, Vector3F.Zero);
}
float invDet = 1.0f / det;
// Calculate the distance from triangle.Point0 to the ray origin
Vector3F tvec = ray.Origin - triangle.Point0;
// Calculate U parameter and test bounds
float u = Vector3F.Dot(tvec, pvec) * invDet;
if ((u < 0.0f) || u > 1.0f)
return new IntersectionPair(false, Vector3F.Zero);
// Prepare to test the V parameter
Vector3F qvec = Vector3F.CrossProduct(tvec, edge1);
// Calculate V parameter and test bounds
float v = Vector3F.Dot(ray.Direction, qvec) * invDet;
if ((v < 0.0f) || v > 1.0f)
return new IntersectionPair(false, Vector3F.Zero);
// The ray intersects the triangle
// Calculate the distance from the ray origin to the intersection point.
//t = Vector3F.Dot(edge2, qvec) * invDet;
return new IntersectionPair(true, triangle.FromBarycentric(u,v));
}
/// <summary>
/// Initializes a new instance of the <see cref="Triangle"/> class using a given Triangle.
/// </summary>
/// <param name="t">A <see cref="Triangle"/> instance.</param>
public Triangle(Triangle t)
{
_p0 = t._p0;
_p1 = t._p1;
_p2 = t._p2;
}
