BEPUphysics.CollisionTests.CollisionAlgorithms.GJK.RaySimplex.GetErrorTolerance C# (CSharp) Method

        public float GetErrorTolerance(ref Vector3 rayOrigin)
        {
            switch (State)
            {
                case SimplexState.Point:
                    float distanceA;
                    Vector3.DistanceSquared(ref A, ref rayOrigin, out distanceA);
                    return distanceA;
                case SimplexState.Segment:
                    float distanceB;
                    Vector3.DistanceSquared(ref A, ref rayOrigin, out distanceA);
                    Vector3.DistanceSquared(ref B, ref rayOrigin, out distanceB);
                    return MathHelper.Max(distanceA, distanceB);
                case SimplexState.Triangle:
                    float distanceC;
                    Vector3.DistanceSquared(ref A, ref rayOrigin, out distanceA);
                    Vector3.DistanceSquared(ref B, ref rayOrigin, out distanceB);
                    Vector3.DistanceSquared(ref C, ref rayOrigin, out distanceC);
                    return MathHelper.Max(distanceA, MathHelper.Max(distanceB, distanceC));
                case SimplexState.Tetrahedron:
                    float distanceD;
                    Vector3.DistanceSquared(ref A, ref rayOrigin, out distanceA);
                    Vector3.DistanceSquared(ref B, ref rayOrigin, out distanceB);
                    Vector3.DistanceSquared(ref C, ref rayOrigin, out distanceC);
                    Vector3.DistanceSquared(ref D, ref rayOrigin, out distanceD);
                    return MathHelper.Max(distanceA, MathHelper.Max(distanceB, MathHelper.Max(distanceC, distanceD)));
            }
            return 0;
        }

        ///<summary>
        /// Casts a fat (sphere expanded) ray against the shape.
        ///</summary>
        ///<param name="ray">Ray to test against the shape.</param>
        ///<param name="radius">Radius of the ray.</param>
        ///<param name="shape">Shape to test against.</param>
        ///<param name="shapeTransform">Transform to apply to the shape for the test.</param>
        ///<param name="maximumLength">Maximum length of the ray in units of the ray direction's length.</param>
        ///<param name="hit">Hit data of the sphere cast, if any.</param>
        ///<returns>Whether or not the sphere cast hit the shape.</returns>
        public static bool SphereCast(Ray ray, float radius, ConvexShape shape, ref RigidTransform shapeTransform, float maximumLength,
                                   out RayHit hit)
        {
            //Transform the ray into the object's local space.
            Vector3.Subtract(ref ray.Position, ref shapeTransform.Position, out ray.Position);
            Quaternion conjugate;
            Quaternion.Conjugate(ref shapeTransform.Orientation, out conjugate);
            Quaternion.Transform(ref ray.Position, ref conjugate, out ray.Position);
            Quaternion.Transform(ref ray.Direction, ref conjugate, out ray.Direction);

            Vector3 w, p;
            hit.T = 0;
            hit.Location = ray.Position;
            hit.Normal = Toolbox.ZeroVector;
            Vector3 v = hit.Location;

            RaySimplex simplex = new RaySimplex();

            float vw, vdir;
            int count = 0;

            //This epsilon has a significant impact on performance and accuracy.  Changing it to use BigEpsilon instead increases speed by around 30-40% usually, but jigging is more evident.
            while (v.LengthSquared() >= Toolbox.Epsilon * simplex.GetErrorTolerance(ref ray.Position))
            {
                if (++count > MaximumGJKIterations)
                {
                    //It's taken too long to find a hit.  Numerical problems are probable; quit.
                    hit = new RayHit();
                    return false;
                }

                shape.GetLocalExtremePointWithoutMargin(ref v, out p);
                Vector3 contribution;
                MinkowskiToolbox.ExpandMinkowskiSum(shape.collisionMargin, radius, ref v, out contribution);
                Vector3.Add(ref p, ref contribution, out p);

                Vector3.Subtract(ref hit.Location, ref p, out w);
                Vector3.Dot(ref v, ref w, out vw);
                if (vw > 0)
                {
                    Vector3.Dot(ref v, ref ray.Direction, out vdir);
                    hit.T = hit.T - vw / vdir;
                    if (vdir >= 0)
                    {
                        //We would have to back up!
                        return false;
                    }
                    if (hit.T > maximumLength)
                    {
                        //If we've gone beyond where the ray can reach, there's obviously no hit.
                        return false;
                    }
                    //Shift the ray up.
                    Vector3.Multiply(ref ray.Direction, hit.T, out hit.Location);
                    Vector3.Add(ref hit.Location, ref ray.Position, out hit.Location);
                    hit.Normal = v;
                }

                RaySimplex shiftedSimplex;
                simplex.AddNewSimplexPoint(ref p, ref hit.Location, out shiftedSimplex);

                shiftedSimplex.GetPointClosestToOrigin(ref simplex, out v);

            }
            //Transform the hit data into world space.
            Quaternion.Transform(ref hit.Normal, ref shapeTransform.Orientation, out hit.Normal);
            Quaternion.Transform(ref hit.Location, ref shapeTransform.Orientation, out hit.Location);
            Vector3.Add(ref hit.Location, ref shapeTransform.Position, out hit.Location);

            return true;
        }