| public abstract GetLocalExtremePointWithoutMargin ( Vector3 &direction, Vector3 &extremePoint ) : void | ||
| direction | Vector3 | Direction to find the extreme point in. |
| extremePoint | Vector3 | Extreme point on the shape. |
| return | void | |
/// <summary>
/// Computes a convex shape description for a TransformableShape and applies it.
/// </summary>
public void UpdateConvexShapeInfo()
{
//Compute the volume distribution.
var samples = CommonResources.GetVectorList();
if (samples.Capacity < InertiaHelper.SampleDirections.Length)
{
samples.Capacity = InertiaHelper.SampleDirections.Length;
}
samples.Count = InertiaHelper.SampleDirections.Length;
for (int i = 0; i < InertiaHelper.SampleDirections.Length; ++i)
{
shape.GetLocalExtremePointWithoutMargin(ref InertiaHelper.SampleDirections[i], out samples.Elements[i]);
}
var triangles = CommonResources.GetIntList();
ConvexHullHelper.GetConvexHull(samples, triangles);
Fix64 volume;
InertiaHelper.ComputeShapeDistribution(samples, triangles, out volume, out volumeDistribution);
Volume = volume;
//Estimate the minimum radius based on the surface mesh.
MinimumRadius = InertiaHelper.ComputeMinimumRadius(samples, triangles, ref Toolbox.ZeroVector) + collisionMargin;
MaximumRadius = ComputeMaximumRadius();
CommonResources.GiveBack(samples);
CommonResources.GiveBack(triangles);
}
///<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="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 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 v;
Vector3 negativeN;
Vector3.Negate(ref direction, out negativeN);
shapeB.GetExtremePointWithoutMargin(negativeN, ref localTransformB, out v);
Vector3.Subtract(ref extremePoint, ref v, out extremePoint);
ExpandMinkowskiSum(shapeA.collisionMargin, shapeB.collisionMargin, ref direction, out v);
Vector3.Add(ref extremePoint, ref v, out extremePoint);
}
///<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;
}
///<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;
}
///<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="extremePoint">The extreme point in the local space of A.</param>
public static void GetLocalMinkowskiExtremePoint(ConvexShape shapeA, ConvexShape shapeB, ref System.Numerics.Vector3 direction, ref RigidTransform localTransformB,
out System.Numerics.Vector3 extremePointA, out System.Numerics.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);
System.Numerics.Vector3 v;
Vector3Ex.Negate(ref direction, out v);
System.Numerics.Vector3 extremePointB;
shapeB.GetExtremePointWithoutMargin(v, ref localTransformB, out extremePointB);
ExpandMinkowskiSum(shapeA.collisionMargin, shapeB.collisionMargin, direction, ref extremePointA, ref extremePointB);
Vector3Ex.Subtract(ref extremePointA, ref extremePointB, out extremePoint);
}
///<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 System.Numerics.Vector3 direction, ref RigidTransform localTransformB, out System.Numerics.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);
System.Numerics.Vector3 extremePointB;
System.Numerics.Vector3 negativeN;
Vector3Ex.Negate(ref direction, out negativeN);
shapeB.GetExtremePointWithoutMargin(negativeN, ref localTransformB, out extremePointB);
Vector3Ex.Subtract(ref extremePoint, ref extremePointB, out extremePoint);
}
