BEPUutilities.AffineTransform.Invert C# (CSharp) Method

        public static void Invert(ref AffineTransform transform, out AffineTransform inverse)
        {
            Matrix3x3.Invert(ref transform.LinearTransform, out inverse.LinearTransform);
            Matrix3x3.Transform(ref transform.Translation, ref inverse.LinearTransform, out inverse.Translation);
            Vector3.Negate(ref inverse.Translation, out inverse.Translation);
        }

        ///<summary>
        /// Tests a ray against the instance.
        ///</summary>
        ///<param name="ray">Ray to test.</param>
        ///<param name="maximumLength">Maximum length of the ray to test; in units of the ray's direction's length.</param>
        ///<param name="sidedness">Sidedness to use during the ray cast.  This does not have to be the same as the mesh's sidedness.</param>
        ///<param name="rayHit">The hit location of the ray on the mesh, if any.</param>
        ///<returns>Whether or not the ray hit the mesh.</returns>
        public bool RayCast(Ray ray, float maximumLength, TriangleSidedness sidedness, out RayHit rayHit)
        {
            //Put the ray into local space.
            Ray             localRay;
            AffineTransform inverse;

            AffineTransform.Invert(ref worldTransform, out inverse);
            Matrix3x3.Transform(ref ray.Direction, ref inverse.LinearTransform, out localRay.Direction);
            AffineTransform.Transform(ref ray.Position, ref inverse, out localRay.Position);

            if (Shape.TriangleMesh.RayCast(localRay, maximumLength, sidedness, out rayHit))
            {
                //Transform the hit into world space.
                Vector3.Multiply(ref ray.Direction, rayHit.T, out rayHit.Location);
                Vector3.Add(ref rayHit.Location, ref ray.Position, out rayHit.Location);
                Matrix3x3.TransformTranspose(ref rayHit.Normal, ref inverse.LinearTransform, out rayHit.Normal);
                return(true);
            }
            rayHit = new RayHit();
            return(false);
        }