public static bool CollisionTest(Ray ray, IPhysical obj, PhysicsMesh mesh, out float dist)
{
Vector3 start = new Vector3(ray.X, ray.Y, ray.Z);
Vector3 direction = new Vector3(ray.I, ray.J, ray.K);
dist = Single.MaxValue;
// Construct a matrix to transform to scene space
Matrix4 transform = Matrix4.Identity;
transform *= Matrix4.CreateScale(obj.Scale);
transform *= Matrix4.CreateFromQuaternion(obj.RelativeRotation);
transform *= Matrix4.CreateTranslation(obj.RelativePosition);
ILinkable parent = obj.Parent;
if (parent != null)
{
// Apply parent rotation and translation
transform *= Matrix4.CreateFromQuaternion(parent.RelativeRotation);
transform *= Matrix4.CreateTranslation(parent.RelativePosition);
}
// Iterate through all of the triangles in the mesh, doing a ray-triangle intersection
for (int i = 0; i < mesh.Indices.Length; i += 3)
{
Vector3 point0 = mesh.Vertices[mesh.Indices[i + 0]] * transform;
Vector3 point1 = mesh.Vertices[mesh.Indices[i + 1]] * transform;
Vector3 point2 = mesh.Vertices[mesh.Indices[i + 2]] * transform;
float thisDist;
if (RayTriangle.CollisionTestCull(start, direction, point0, point1, point2, out thisDist))
{
if (thisDist < dist)
dist = thisDist;
}
}
return dist < Single.MaxValue;
}
/// <summary>
/// Calculates the approximate volume of a scaled mesh
/// </summary>
/// <param name="mesh">Mesh data</param>
/// <param name="scale">Object scale</param>
/// <returns>Approximate volume of the mesh</returns>
public static float GetMeshVolume(PhysicsMesh mesh, Vector3 scale)
{
const float OO_SIX = 1f / 6f;
double volume = 0.0f;
// Formula adapted from Stan Melax's algorithm: <http://www.melax.com/volint.html>
for (int i = 0; i < mesh.Indices.Length; i += 3)
{
Vector3 v0 = mesh.Vertices[mesh.Indices[i + 0]];
Vector3 v1 = mesh.Vertices[mesh.Indices[i + 1]];
Vector3 v2 = mesh.Vertices[mesh.Indices[i + 2]];
volume += Determinant3x3(v0, v1, v2);
}
return (float)(volume * OO_SIX) * scale.X * scale.Y * scale.Z;
}
