///<summary> /// Gets the extreme point of the minkowski difference of shapeA and shapeB in the local space of shapeA, without a margin. ///</summary> ///<param name="shapeA">First shape.</param> ///<param name="shapeB">Second shape.</param> ///<param name="direction">Extreme point direction in local space.</param> ///<param name="localTransformB">Transform of shapeB in the local space of A.</param> ///<param name="extremePoint">The extreme point in the local space of A.</param> public static void GetLocalMinkowskiExtremePointWithoutMargin(ConvexShape shapeA, ConvexShape shapeB, ref Vector3 direction, ref RigidTransform localTransformB, out Vector3 extremePoint) { //Extreme point of A-B along D = (extreme point of A along D) - (extreme point of B along -D) shapeA.GetLocalExtremePointWithoutMargin(ref direction, out extremePoint); Vector3 extremePointB; Vector3 negativeN; Vector3.Negate(ref direction, out negativeN); shapeB.GetExtremePointWithoutMargin(negativeN, ref localTransformB, out extremePointB); Vector3.Subtract(ref extremePoint, ref extremePointB, out extremePoint); }
///<summary> /// Gets the extreme point of the minkowski difference of shapeA and shapeB in the local space of shapeA. ///</summary> ///<param name="shapeA">First shape.</param> ///<param name="shapeB">Second shape.</param> ///<param name="direction">Extreme point direction in local space.</param> ///<param name="localTransformB">Transform of shapeB in the local space of A.</param> /// <param name="extremePointA">The extreme point on shapeA.</param> /// <param name="extremePointB">The extreme point on shapeB.</param> ///<param name="extremePoint">The extreme point in the local space of A.</param> public static void GetLocalMinkowskiExtremePoint(ConvexShape shapeA, ConvexShape shapeB, ref Vector3 direction, ref RigidTransform localTransformB, out Vector3 extremePointA, out Vector3 extremePointB, out Vector3 extremePoint) { //Extreme point of A-B along D = (extreme point of A along D) - (extreme point of B along -D) shapeA.GetLocalExtremePointWithoutMargin(ref direction, out extremePointA); Vector3 v; Vector3.Negate(ref direction, out v); shapeB.GetExtremePointWithoutMargin(v, ref localTransformB, out extremePointB); ExpandMinkowskiSum(shapeA.collisionMargin, shapeB.collisionMargin, direction, ref extremePointA, ref extremePointB); Vector3.Subtract(ref extremePointA, ref extremePointB, out extremePoint); }
///<summary> /// Adds a new point to the simplex. ///</summary> ///<param name="shapeA">First shape in the pair.</param> ///<param name="shapeB">Second shape in the pair.</param> ///<param name="iterationCount">Current iteration count.</param> ///<param name="closestPoint">Current point on simplex closest to origin.</param> ///<returns>Whether or not GJK should exit due to a lack of progression.</returns> public bool GetNewSimplexPoint(ConvexShape shapeA, ConvexShape shapeB, int iterationCount, ref Vector3 closestPoint) { Vector3 negativeDirection; Vector3.Negate(ref closestPoint, out negativeDirection); Vector3 sa, sb; shapeA.GetLocalExtremePointWithoutMargin(ref negativeDirection, out sa); shapeB.GetExtremePointWithoutMargin(closestPoint, ref LocalTransformB, out sb); Vector3 S; Vector3.Subtract(ref sa, ref sb, out S); //If S is not further towards the origin along negativeDirection than closestPoint, then we're done. float dotS; Vector3.Dot(ref S, ref negativeDirection, out dotS); //-P * S float distanceToClosest = closestPoint.LengthSquared(); float progression = dotS + distanceToClosest; //It's likely that the system is oscillating between two or more states, usually because of a degenerate simplex. //Rather than detect specific problem cases, this approach just lets it run and catches whatever falls through. //During oscillation, one of the states is usually just BARELY outside of the numerical tolerance. //After a bunch of iterations, the system lets it pick the 'better' one. if (iterationCount > GJKToolbox.HighGJKIterations && distanceToClosest - previousDistanceToClosest < DistanceConvergenceEpsilon * errorTolerance) { return(true); } if (distanceToClosest < previousDistanceToClosest) { previousDistanceToClosest = distanceToClosest; } //If "A" is the new point always, then the switch statement can be removed //in favor of just pushing three points up. switch (State) { case SimplexState.Point: if (progression <= (errorTolerance = MathHelper.Max(A.LengthSquared(), S.LengthSquared())) * ProgressionEpsilon) { return(true); } State = SimplexState.Segment; B = S; SimplexA.B = sa; SimplexB.B = sb; return(false); case SimplexState.Segment: if (progression <= (errorTolerance = MathHelper.Max(MathHelper.Max(A.LengthSquared(), B.LengthSquared()), S.LengthSquared())) * ProgressionEpsilon) { return(true); } State = SimplexState.Triangle; C = S; SimplexA.C = sa; SimplexB.C = sb; return(false); case SimplexState.Triangle: if (progression <= (errorTolerance = MathHelper.Max(MathHelper.Max(A.LengthSquared(), B.LengthSquared()), MathHelper.Max(C.LengthSquared(), S.LengthSquared()))) * ProgressionEpsilon) { return(true); } State = SimplexState.Tetrahedron; D = S; SimplexA.D = sa; SimplexB.D = sb; return(false); } return(false); }