/// <summary>
        /// Evaluate this contact with your own manifold and transforms.
        /// </summary>
        /// <param name="manifold">The manifold.</param>
        /// <param name="transformA">The first transform.</param>
        /// <param name="transformB">The second transform.</param>
        private void Evaluate(ref Manifold manifold, ref Transform transformA, ref Transform transformB)
        {
            switch (_type)
            {
            case ContactType.Polygon:
                Collision.CollidePolygons(ref manifold, (PolygonShape)FixtureA.Shape, ref transformA, (PolygonShape)FixtureB.Shape, ref transformB);
                break;

            case ContactType.PolygonAndCircle:
                Collision.CollidePolygonAndCircle(ref manifold, (PolygonShape)FixtureA.Shape, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
                break;

            case ContactType.EdgeAndCircle:
                Collision.CollideEdgeAndCircle(ref manifold, (EdgeShape)FixtureA.Shape, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
                break;

            case ContactType.EdgeAndPolygon:
                Collision.CollideEdgeAndPolygon(ref manifold, (EdgeShape)FixtureA.Shape, ref transformA, (PolygonShape)FixtureB.Shape, ref transformB);
                break;

            case ContactType.ChainAndCircle:
                ChainShape chain = (ChainShape)FixtureA.Shape;
                chain.GetChildEdge(_edge, ChildIndexA);
                Collision.CollideEdgeAndCircle(ref manifold, _edge, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
                break;

            case ContactType.ChainAndPolygon:
                ChainShape loop2 = (ChainShape)FixtureA.Shape;
                loop2.GetChildEdge(_edge, ChildIndexA);
                Collision.CollideEdgeAndPolygon(ref manifold, _edge, ref transformA, (PolygonShape)FixtureB.Shape, ref transformB);
                break;

            case ContactType.Circle:
                Collision.CollideCircles(ref manifold, (CircleShape)FixtureA.Shape, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
                break;
            }
        }