/// <summary>
/// Non-allocating version of Ray / Triangle intersection.
/// </summary>
/// <param name="origin"></param>
/// <param name="dir"></param>
/// <param name="vert0"></param>
/// <param name="vert1"></param>
/// <param name="vert2"></param>
/// <param name="distance"></param>
/// <param name="normal"></param>
/// <returns></returns>
internal static bool RayIntersectsTriangle2(Vector3 origin,
Vector3 dir,
Vector3 vert0,
Vector3 vert1,
Vector3 vert2,
out float distance,
out Vector3 normal)
{
Math.Subtract(vert0, vert1, ref tv1);
Math.Subtract(vert0, vert2, ref tv2);
normal = Vector3.Cross(tv1, tv2);
distance = 0f;
// backface culling
if (Vector3.Dot(dir, normal) > 0)
{
return(false);
}
Math.Cross(dir, tv2, ref tv4);
float det = Vector3.Dot(tv1, tv4);
if (det < Mathf.Epsilon)
{
return(false);
}
Math.Subtract(vert0, origin, ref tv3);
float u = Vector3.Dot(tv3, tv4);
if (u < 0f || u > det)
{
return(false);
}
Math.Cross(tv3, tv1, ref tv4);
float v = Vector3.Dot(dir, tv4);
if (v < 0f || u + v > det)
{
return(false);
}
distance = Vector3.Dot(tv2, tv4) * (1f / det);
// no hit if point is behind the ray origin
return(distance > 0f);
}
/// <summary>
/// Non-allocating version of Ray / Triangle intersection.
/// </summary>
/// <param name="origin"></param>
/// <param name="dir"></param>
/// <param name="vert0"></param>
/// <param name="vert1"></param>
/// <param name="vert2"></param>
/// <param name="distance"></param>
/// <param name="normal"></param>
/// <returns></returns>
internal static bool RayIntersectsTriangle2(Vector3 origin,
Vector3 dir,
Vector3 vert0,
Vector3 vert1,
Vector3 vert2,
ref float distance,
ref Vector3 normal)
{
Math.Subtract(vert0, vert1, ref tv1);
Math.Subtract(vert0, vert2, ref tv2);
Math.Cross(dir, tv2, ref tv4);
float det = Vector3.Dot(tv1, tv4);
if (det < Mathf.Epsilon)
{
return(false);
}
Math.Subtract(vert0, origin, ref tv3);
float u = Vector3.Dot(tv3, tv4);
if (u < 0f || u > det)
{
return(false);
}
Math.Cross(tv3, tv1, ref tv4);
float v = Vector3.Dot(dir, tv4);
if (v < 0f || u + v > det)
{
return(false);
}
distance = Vector3.Dot(tv2, tv4) * (1f / det);
Math.Cross(tv1, tv2, ref normal);
return(true);
}
