/// <summary>
/// Adapted from http://www.cs.virginia.edu/~gfx/Courses/2003/ImageSynthesis/papers/Acceleration/Fast%20MinimumStorage%20RayTriangle%20Intersection.pdf
/// </summary>
/// <param name="origin">Origin point of the ray</param>
/// <param name="direction">Unit vector representing the direction of the ray</param>
/// <param name="vert0">Position of the first triangle corner</param>
/// <param name="vert1">Position of the second triangle corner</param>
/// <param name="vert2">Position of the third triangle corner</param>
/// <param name="collisionPoint">The collision point in the triangle</param>
/// <returns>True if the ray passes through the triangle, otherwise false</returns>
static bool RayTriangleIntersection(Vertex origin, Vertex direction, Vertex vert0, Vertex vert1, Vertex vert2, out Vertex collisionPoint)
{
const float EPSILON = 0.00001f;
Vertex edge1, edge2, pvec;
float determinant, invDeterminant;
// Find vectors for two edges sharing vert0
edge1 = vert1 - vert0;
edge2 = vert2 - vert0;
// Begin calculating the determinant
pvec = direction.cross(edge2);
// If the determinant is near zero, ray lies in plane of triangle
determinant = edge1.dot(pvec);
if (determinant > -EPSILON && determinant < EPSILON)
{
collisionPoint = (Vertex)Vertex.Zero;
return(false);
}
invDeterminant = 1f / determinant;
// Calculate distance from vert0 to ray origin
Vertex tvec = origin - vert0;
// Calculate U parameter and test bounds
float u = tvec.dot(pvec) * invDeterminant;
if (u < 0.0f || u > 1.0f)
{
collisionPoint = (Vertex)Vertex.Zero;
return(false);
}
// Prepare to test V parameter
Vertex qvec = tvec.cross(edge1);
// Calculate V parameter and test bounds
float v = direction.dot(qvec) * invDeterminant;
if (v < 0.0f || u + v > 1.0f)
{
collisionPoint = (Vertex)Vertex.Zero;
return(false);
}
//t = Vertex.Dot(edge2, qvec) * invDeterminant;
collisionPoint = new Vertex(
vert0.X + u * (vert1.X - vert0.X) + v * (vert2.X - vert0.X),
vert0.Y + u * (vert1.Y - vert0.Y) + v * (vert2.Y - vert0.Y),
vert0.Z + u * (vert1.Z - vert0.Z) + v * (vert2.Z - vert0.Z));
return(true);
}
/// <summary>
/// Adapted from http://www.cs.virginia.edu/~gfx/Courses/2003/ImageSynthesis/papers/Acceleration/Fast%20MinimumStorage%20RayTriangle%20Intersection.pdf
/// </summary>
/// <param name="origin">Origin point of the ray</param>
/// <param name="direction">Unit vector representing the direction of the ray</param>
/// <param name="vert0">Position of the first triangle corner</param>
/// <param name="vert1">Position of the second triangle corner</param>
/// <param name="vert2">Position of the third triangle corner</param>
/// <param name="collisionPoint">The collision point in the triangle</param>
/// <returns>True if the ray passes through the triangle, otherwise false</returns>
static bool RayTriangleIntersection(Vertex origin, Vertex direction, Vertex vert0, Vertex vert1, Vertex vert2, out Vertex collisionPoint)
{
const float EPSILON = 0.00001f;
Vertex edge1, edge2, pvec;
float determinant, invDeterminant;
// Find vectors for two edges sharing vert0
edge1 = vert1 - vert0;
edge2 = vert2 - vert0;
// Begin calculating the determinant
pvec = direction.cross(edge2);
// If the determinant is near zero, ray lies in plane of triangle
determinant = edge1.dot(pvec);
if (determinant > -EPSILON && determinant < EPSILON)
{
collisionPoint = (Vertex)Vertex.Zero;
return false;
}
invDeterminant = 1f / determinant;
// Calculate distance from vert0 to ray origin
Vertex tvec = origin - vert0;
// Calculate U parameter and test bounds
float u = tvec.dot(pvec) * invDeterminant;
if (u < 0.0f || u > 1.0f)
{
collisionPoint = (Vertex)Vertex.Zero;
return false;
}
// Prepare to test V parameter
Vertex qvec = tvec.cross(edge1);
// Calculate V parameter and test bounds
float v = direction.dot(qvec) * invDeterminant;
if (v < 0.0f || u + v > 1.0f)
{
collisionPoint = (Vertex)Vertex.Zero;
return false;
}
//t = Vertex.Dot(edge2, qvec) * invDeterminant;
collisionPoint = new Vertex(
vert0.X + u * (vert1.X - vert0.X) + v * (vert2.X - vert0.X),
vert0.Y + u * (vert1.Y - vert0.Y) + v * (vert2.Y - vert0.Y),
vert0.Z + u * (vert1.Z - vert0.Z) + v * (vert2.Z - vert0.Z));
return true;
}
