/// <summary>
/// Performs a raycast against the mesh triangles and returns info
/// about the closest hit or null if no triangle was hit by the ray.
/// </summary>
/// <param name="meshTransform">
/// The mesh transform which brings the mesh in the same space as the
/// ray.
/// </param>
/// <remarks>
/// This method will build the tree if it hasn't already been built.
/// </remarks>
public MeshRayHit RaycastClosest(Ray ray, Matrix4x4 meshTransform)
{
// Build the tree if it hasn't already been built
if (!_isBuilt)
{
Build();
}
// Work in mesh local space by transforming the ray by the inverse of
// the mesh transform. It is faster to perform this transformation here
// instead of transforming every possibly hit triangle by 'meshTransform'.
Ray modelSpaceRay = ray.InverseTransform(meshTransform);
// Get the list of tree nodes which are hit by the ray
List <SphereTreeNodeRayHit <MeshTriangle> > nodeHits = _tree.RaycastAll(modelSpaceRay);
if (nodeHits.Count == 0)
{
return(null);
}
// Store data in preparation for closest hit identification
float t;
float minT = float.MaxValue;
MeshTriangle closestTriangle = null;
bool foundTriangle = false;
// Loop through each node hit
foreach (var nodeHit in nodeHits)
{
// Get the associated mesh triangle and check if the ray intersects it
MeshTriangle meshTriangle = nodeHit.HitNode.Data;
if (TriangleMath.Raycast(modelSpaceRay, out t, meshTriangle.Vertex0, meshTriangle.Vertex1, meshTriangle.Vertex2))
{
if (Vector3.Dot(modelSpaceRay.direction, meshTriangle.Normal) < 0.0f)
{
// If the intersection offset is smaller than what we have so far,
// it means we have a new closest hit.
if (t < minT)
{
minT = t;
closestTriangle = meshTriangle;
foundTriangle = true;
}
}
}
}
// If we found a triangle, we can return the mesh ray hit information
if (foundTriangle)
{
// Convert the t value in world space. Do the same for the normal.
Vector3 worldHit = meshTransform.MultiplyPoint(modelSpaceRay.GetPoint(minT));
minT = (ray.origin - worldHit).magnitude / ray.direction.magnitude;
Vector3 transformedNormal = meshTransform.inverse.transpose.MultiplyVector(closestTriangle.Normal).normalized;
// Return the hit instance
return(new MeshRayHit(ray, closestTriangle.TriangleIndex, minT, transformedNormal));
}
return(null);
}