/// <summary>
/// Removes a child from a compound body.
/// </summary>
/// <param name="childContributions">List of distribution information associated with each child shape of the whole compound shape used by the compound being split.</param>
/// <param name="removalPredicate">Delegate which determines if a child in the original compound should be moved to the new compound.</param>
/// <param name="distributionInfo">Volume, volume distribution, and center information about the new form of the original compound collidable.</param>
/// <param name="compound">Original compound to have a child removed.</param>
/// <returns>Whether or not the predicate returned true for any element in the original compound and split the compound.</returns>
public static bool RemoveChildFromCompound(Entity <CompoundCollidable> compound, Func <CompoundChild, bool> removalPredicate, IList <ShapeDistributionInformation> childContributions,
out ShapeDistributionInformation distributionInfo)
{
float weight;
float removedWeight;
Vector3 removedCenter;
if (RemoveChildFromCompound(compound.CollisionInformation, removalPredicate, childContributions, out distributionInfo, out weight, out removedWeight, out removedCenter))
{
//Reconfigure the entities using the data computed in the split.
//Only bother if there are any children left in the compound!
if (compound.CollisionInformation.Children.Count > 0)
{
float originalMass = compound.mass;
float newMass = (weight / (weight + removedWeight)) * originalMass;
Matrix3X3.Multiply(ref distributionInfo.VolumeDistribution, newMass * InertiaHelper.InertiaTensorScale, out distributionInfo.VolumeDistribution);
compound.Initialize(compound.CollisionInformation, newMass, distributionInfo.VolumeDistribution, distributionInfo.Volume);
RemoveReposition(compound, ref distributionInfo, weight, removedWeight, ref removedCenter);
}
return(true);
}
else
{
return(false);
}
}
/// <summary>
/// Splits a single compound collidable into two separate compound collidables and computes information needed by the simulation.
/// </summary>
/// <param name="childContributions">List of distribution information associated with each child shape of the whole compound shape used by the compound being split.</param>
/// <param name="splitPredicate">Delegate which determines if a child in the original compound should be moved to the new compound.</param>
/// <param name="a">Original compound to be split. Children in this compound will be removed and added to the other compound.</param>
/// <param name="b">Compound to receive children removed from the original compound.</param>
/// <param name="distributionInfoA">Volume, volume distribution, and center information about the new form of the original compound collidable.</param>
/// <param name="distributionInfoB">Volume, volume distribution, and center information about the new compound collidable.</param>
/// <returns>Whether or not the predicate returned true for any element in the original compound and split the compound.</returns>
public static bool SplitCompound(IList <ShapeDistributionInformation> childContributions, Func <CompoundChild, bool> splitPredicate,
Entity <CompoundCollidable> a, out Entity <CompoundCollidable> b,
out ShapeDistributionInformation distributionInfoA, out ShapeDistributionInformation distributionInfoB)
{
CompoundCollidable bCollidable = new CompoundCollidable();
bCollidable.Shape = a.CollisionInformation.Shape;
b = new Entity <CompoundCollidable>();
float weightA, weightB;
if (SplitCompound(childContributions, splitPredicate, a.CollisionInformation, bCollidable, out distributionInfoA, out distributionInfoB, out weightA, out weightB))
{
//Reconfigure the entities using the data computed in the split.
float originalMass = a.mass;
float newMassA = (weightA / (weightA + weightB)) * originalMass;
Matrix3X3.Multiply(ref distributionInfoA.VolumeDistribution, newMassA * InertiaHelper.InertiaTensorScale, out distributionInfoA.VolumeDistribution);
a.Initialize(a.CollisionInformation, newMassA, distributionInfoA.VolumeDistribution, distributionInfoA.Volume);
float newMassB = (weightB / (weightA + weightB)) * originalMass;
Matrix3X3.Multiply(ref distributionInfoB.VolumeDistribution, newMassB * InertiaHelper.InertiaTensorScale, out distributionInfoB.VolumeDistribution);
b.Initialize(bCollidable, newMassB, distributionInfoB.VolumeDistribution, distributionInfoB.Volume);
Reposition(a, b, ref distributionInfoA, ref distributionInfoB, weightA, weightB);
return(true);
}
else
{
return(false);
}
}
static void RemoveReposition(Entity compound, ref ShapeDistributionInformation distributionInfo, float weight, float removedWeight, ref Vector3 removedCenter)
{
//The compounds are not aligned with the original's position yet.
//In order to align them, first look at the centers the split method computed.
//They are offsets from the center of the original shape in local space.
//These can be used to reposition the objects in world space.
Vector3 weightedA, weightedB;
Vector3.Multiply(ref distributionInfo.Center, weight, out weightedA);
Vector3.Multiply(ref removedCenter, removedWeight, out weightedB);
Vector3 newLocalCenter;
Vector3.Add(ref weightedA, ref weightedB, out newLocalCenter);
Vector3.Divide(ref newLocalCenter, weight + removedWeight, out newLocalCenter);
Vector3 localOffset;
Vector3.Subtract(ref distributionInfo.Center, ref newLocalCenter, out localOffset);
Vector3 originalPosition = compound.position;
Vector3 offset = Vector3.Transform(localOffset, compound.orientation);
compound.Position = originalPosition + offset;
Vector3 originalLinearVelocity = compound.linearVelocity;
Vector3 originalAngularVelocity = compound.angularVelocity;
compound.AngularVelocity = originalAngularVelocity;
compound.LinearVelocity = originalLinearVelocity + Vector3.Cross(originalAngularVelocity, offset);
}
/// <summary>
/// Splits a single compound collidable into two separate compound collidables and computes information needed by the simulation.
/// </summary>
/// <param name="splitPredicate">Delegate which determines if a child in the original compound should be moved to the new compound.</param>
/// <param name="distributionInfoA">Volume, volume distribution, and center information about the new form of the original compound collidable.</param>
/// <param name="distributionInfoB">Volume, volume distribution, and center information about the new compound collidable.</param>
/// <param name="a">Original compound to be split. Children in this compound will be removed and added to the other compound.</param>
/// <param name="b">Compound to receive children removed from the original compound.</param>
/// <returns>Whether or not the predicate returned true for any element in the original compound and split the compound.</returns>
public static bool SplitCompound(Func <CompoundChild, bool> splitPredicate,
Entity <CompoundCollidable> a, Entity <CompoundCollidable> b,
out ShapeDistributionInformation distributionInfoA, out ShapeDistributionInformation distributionInfoB)
{
float weightA, weightB;
if (SplitCompound(splitPredicate, a.CollisionInformation, b.CollisionInformation, out distributionInfoA, out distributionInfoB, out weightA, out weightB))
{
//Reconfigure the entities using the data computed in the split.
float originalMass = a.mass;
if (a.CollisionInformation.children.Count > 0)
{
float newMassA = (weightA / (weightA + weightB)) * originalMass;
Matrix3x3.Multiply(ref distributionInfoA.VolumeDistribution, newMassA * InertiaHelper.InertiaTensorScale, out distributionInfoA.VolumeDistribution);
a.Initialize(a.CollisionInformation, newMassA, distributionInfoA.VolumeDistribution);
}
if (b.CollisionInformation.children.Count > 0)
{
float newMassB = (weightB / (weightA + weightB)) * originalMass;
Matrix3x3.Multiply(ref distributionInfoB.VolumeDistribution, newMassB * InertiaHelper.InertiaTensorScale, out distributionInfoB.VolumeDistribution);
b.Initialize(b.CollisionInformation, newMassB, distributionInfoB.VolumeDistribution);
}
SplitReposition(a, b, ref distributionInfoA, ref distributionInfoB, weightA, weightB);
return(true);
}
return(false);
}
static void SplitReposition(Entity a, Entity b, ref ShapeDistributionInformation distributionInfoA, ref ShapeDistributionInformation distributionInfoB, float weightA, float weightB)
{
//The compounds are not aligned with the original's position yet.
//In order to align them, first look at the centers the split method computed.
//They are offsets from the center of the original shape in local space.
//These can be used to reposition the objects in world space.
System.Numerics.Vector3 weightedA, weightedB;
Vector3Ex.Multiply(ref distributionInfoA.Center, weightA, out weightedA);
Vector3Ex.Multiply(ref distributionInfoB.Center, weightB, out weightedB);
System.Numerics.Vector3 newLocalCenter;
Vector3Ex.Add(ref weightedA, ref weightedB, out newLocalCenter);
Vector3Ex.Divide(ref newLocalCenter, weightA + weightB, out newLocalCenter);
System.Numerics.Vector3 localOffsetA;
System.Numerics.Vector3 localOffsetB;
Vector3Ex.Subtract(ref distributionInfoA.Center, ref newLocalCenter, out localOffsetA);
Vector3Ex.Subtract(ref distributionInfoB.Center, ref newLocalCenter, out localOffsetB);
System.Numerics.Vector3 originalPosition = a.position;
b.Orientation = a.Orientation;
System.Numerics.Vector3 offsetA = QuaternionEx.Transform(localOffsetA, a.Orientation);
System.Numerics.Vector3 offsetB = QuaternionEx.Transform(localOffsetB, a.Orientation);
a.Position = originalPosition + offsetA;
b.Position = originalPosition + offsetB;
System.Numerics.Vector3 originalLinearVelocity = a.linearVelocity;
System.Numerics.Vector3 originalAngularVelocity = a.angularVelocity;
a.AngularVelocity = originalAngularVelocity;
b.AngularVelocity = originalAngularVelocity;
a.LinearVelocity = originalLinearVelocity + System.Numerics.Vector3.Cross(originalAngularVelocity, offsetA);
b.LinearVelocity = originalLinearVelocity + System.Numerics.Vector3.Cross(originalAngularVelocity, offsetB);
}
static void Reposition(Entity a, Entity b, ref ShapeDistributionInformation distributionInfoA, ref ShapeDistributionInformation distributionInfoB, float weightA, float weightB)
{
//The compounds are not aligned with the original's position yet.
//In order to align them, first look at the centers the split method computed.
//They are offsets from the center of the original shape in local space.
//These can be used to reposition the objects in world space.
Vector3 weightedA, weightedB;
Vector3.Multiply(ref distributionInfoA.Center, weightA, out weightedA);
Vector3.Multiply(ref distributionInfoB.Center, weightB, out weightedB);
Vector3 newLocalCenter;
Vector3.Add(ref weightedA, ref weightedB, out newLocalCenter);
Vector3.Divide(ref newLocalCenter, weightA + weightB, out newLocalCenter);
Vector3 localOffsetA;
Vector3 localOffsetB;
Vector3.Subtract(ref distributionInfoA.Center, ref newLocalCenter, out localOffsetA);
Vector3.Subtract(ref distributionInfoB.Center, ref newLocalCenter, out localOffsetB);
Vector3 originalPosition = a.position;
b.Orientation = a.Orientation;
//Imagine a split that does not occur right down the middle, but along a far side: (oo - (o - o))
//Both distributions will be positive. Only the first split works properly because there the position
//was aligned with the local space origin.
Vector3 offsetA = Vector3.Transform(localOffsetA, a.Orientation);
Vector3 offsetB = Vector3.Transform(localOffsetB, a.Orientation);
a.Position = originalPosition + offsetA;
b.Position = originalPosition + offsetB;
Vector3 originalLinearVelocity = a.linearVelocity;
Vector3 originalAngularVelocity = a.angularVelocity;
a.AngularVelocity = originalAngularVelocity;
b.AngularVelocity = originalAngularVelocity;
a.LinearVelocity = originalLinearVelocity + Vector3.Cross(originalAngularVelocity, offsetA);
b.LinearVelocity = originalLinearVelocity + Vector3.Cross(originalAngularVelocity, offsetB);
}
public override void ComputeDistributionInformation(out ShapeDistributionInformation shapeInfo)
{
shapeInfo.VolumeDistribution = ComputeVolumeDistribution(out shapeInfo.Volume);
shapeInfo.Center = ComputeCenter();
}
public override void ComputeDistributionInformation(out ShapeDistributionInformation shapeInfo)
{
shapeInfo.VolumeDistribution = ComputeVolumeDistribution(out shapeInfo.Volume);
shapeInfo.Center = ComputeCenter();
}
/// <summary>
/// Splits a single compound collidable into two separate compound collidables and computes information needed by the simulation.
/// </summary>
/// <param name="childContributions">List of distribution information associated with each child shape of the whole compound shape used by the compound being split.</param>
/// <param name="splitPredicate">Delegate which determines if a child in the original compound should be moved to the new compound.</param>
/// <param name="a">Original compound to be split. Children in this compound will be removed and added to the other compound.</param>
/// <param name="b">Compound to receive children removed from the original compound.</param>
/// <param name="distributionInfoA">Volume, volume distribution, and center information about the new form of the original compound collidable.</param>
/// <param name="distributionInfoB">Volume, volume distribution, and center information about the new compound collidable.</param>
/// <param name="weightA">Total weight associated with the new form of the original compound collidable.</param>
/// <param name="weightB">Total weight associated with the new compound collidable.</param>
/// <returns>Whether or not the predicate returned true for any element in the original compound and split the compound.</returns>
public static bool SplitCompound(IList <ShapeDistributionInformation> childContributions, Func <CompoundChild, bool> splitPredicate,
CompoundCollidable a, CompoundCollidable b,
out ShapeDistributionInformation distributionInfoA, out ShapeDistributionInformation distributionInfoB,
out float weightA, out float weightB)
{
bool splitOccurred = false;
for (int i = a.children.count - 1; i >= 0; i--)
{
//The shape doesn't change during this process. The entity could, though.
//All of the other collidable information, like the Tag, CollisionRules, Events, etc. all stay the same.
var child = a.children.Elements[i];
if (splitPredicate(child))
{
splitOccurred = true;
a.children.FastRemoveAt(i);
b.children.Add(child);
}
}
if (!splitOccurred)
{
//No split occurred, so we cannot proceed.
distributionInfoA = new ShapeDistributionInformation();
distributionInfoB = new ShapeDistributionInformation();
weightA = 0;
weightB = 0;
return(false);
}
//Compute the contributions from the original shape to the new form of the original collidable.
distributionInfoA = new ShapeDistributionInformation();
weightA = 0;
distributionInfoB = new ShapeDistributionInformation();
weightB = 0;
for (int i = a.children.count - 1; i >= 0; i--)
{
var child = a.children.Elements[i];
var entry = child.Entry;
var contribution = childContributions[child.shapeIndex];
Vector3.Add(ref contribution.Center, ref entry.LocalTransform.Position, out contribution.Center);
Vector3.Multiply(ref contribution.Center, child.Entry.Weight, out contribution.Center);
Vector3.Add(ref contribution.Center, ref distributionInfoA.Center, out distributionInfoA.Center);
distributionInfoA.Volume += contribution.Volume;
weightA += entry.Weight;
}
for (int i = b.children.count - 1; i >= 0; i--)
{
var child = b.children.Elements[i];
var entry = child.Entry;
var contribution = childContributions[child.shapeIndex];
Vector3.Add(ref contribution.Center, ref entry.LocalTransform.Position, out contribution.Center);
Vector3.Multiply(ref contribution.Center, child.Entry.Weight, out contribution.Center);
Vector3.Add(ref contribution.Center, ref distributionInfoB.Center, out distributionInfoB.Center);
distributionInfoB.Volume += contribution.Volume;
weightB += entry.Weight;
}
//Average the center out.
Vector3.Divide(ref distributionInfoA.Center, weightA, out distributionInfoA.Center);
Vector3.Divide(ref distributionInfoB.Center, weightB, out distributionInfoB.Center);
//Note that the 'entry' is from the Shape, and so the translations are local to the shape's center.
//That is not technically the center of the new collidable- distributionInfoA.Center is.
//Offset the child collidables by -distributionInfoA.Center using their local offset.
Vector3 offsetA;
Vector3.Negate(ref distributionInfoA.Center, out offsetA);
Vector3 offsetB;
Vector3.Negate(ref distributionInfoB.Center, out offsetB);
//Compute the unscaled inertia tensor.
for (int i = a.children.count - 1; i >= 0; i--)
{
var child = a.children.Elements[i];
child.CollisionInformation.localPosition = offsetA;
var entry = child.Entry;
var contribution = childContributions[child.shapeIndex];
CompoundShape.TransformContribution(ref entry.LocalTransform, ref distributionInfoA.Center, ref contribution.VolumeDistribution, entry.Weight, out contribution.VolumeDistribution);
Vector3.Add(ref entry.LocalTransform.Position, ref offsetA, out entry.LocalTransform.Position);
Matrix3X3.Add(ref contribution.VolumeDistribution, ref distributionInfoA.VolumeDistribution, out distributionInfoA.VolumeDistribution);
}
for (int i = b.children.count - 1; i >= 0; i--)
{
var child = b.children.Elements[i];
child.CollisionInformation.localPosition = offsetB;
var entry = child.Entry;
var contribution = childContributions[child.shapeIndex];
CompoundShape.TransformContribution(ref entry.LocalTransform, ref distributionInfoB.Center, ref contribution.VolumeDistribution, entry.Weight, out contribution.VolumeDistribution);
Vector3.Add(ref entry.LocalTransform.Position, ref offsetB, out entry.LocalTransform.Position);
Matrix3X3.Add(ref contribution.VolumeDistribution, ref distributionInfoB.VolumeDistribution, out distributionInfoB.VolumeDistribution);
}
//Normalize the volume distribution.
Matrix3X3.Multiply(ref distributionInfoA.VolumeDistribution, 1 / weightA, out distributionInfoA.VolumeDistribution);
Matrix3X3.Multiply(ref distributionInfoB.VolumeDistribution, 1 / weightB, out distributionInfoB.VolumeDistribution);
//Update the hierarchies of the compounds.
//TODO: Create a new method that does this quickly without garbage. Requires a new Reconstruct method which takes a pool which stores the appropriate node types.
a.hierarchy.Tree.Reconstruct(a.children);
b.hierarchy.Tree.Reconstruct(b.children);
return(true);
}
/// <summary>
/// Removes a child from a compound collidable.
/// </summary>
/// <param name="compound">Compound collidable to remove a child from.</param>
/// <param name="removalPredicate">Callback which analyzes a child and determines if it should be removed from the compound.</param>
/// <param name="childContributions">Distribution contributions from all shapes in the compound shape. This can include shapes which are not represented in the compound.</param>
/// <param name="distributionInfo">Distribution information of the new compound.</param>
/// <param name="weight">Total weight of the new compound.</param>
/// <param name="removedWeight">Weight removed from the compound.</param>
/// <param name="removedCenter">Center of the chunk removed from the compound.</param>
/// <returns>Whether or not any removal took place.</returns>
public static bool RemoveChildFromCompound(CompoundCollidable compound, Func <CompoundChild, bool> removalPredicate, IList <ShapeDistributionInformation> childContributions,
out ShapeDistributionInformation distributionInfo, out float weight, out float removedWeight, out Vector3 removedCenter)
{
bool removalOccurred = false;
removedWeight = 0;
removedCenter = new Vector3();
for (int i = compound.children.count - 1; i >= 0; i--)
{
//The shape doesn't change during this process. The entity could, though.
//All of the other collidable information, like the Tag, CollisionRules, Events, etc. all stay the same.
var child = compound.children.Elements[i];
if (removalPredicate(child))
{
removalOccurred = true;
var entry = child.Entry;
removedWeight += entry.Weight;
Vector3 toAdd;
Vector3.Multiply(ref entry.LocalTransform.Position, entry.Weight, out toAdd);
Vector3.Add(ref removedCenter, ref toAdd, out removedCenter);
//The child event handler must be unhooked from the compound.
child.CollisionInformation.events.Parent = null;
compound.children.FastRemoveAt(i);
}
}
if (!removalOccurred)
{
//No removal occurred, so we cannot proceed.
distributionInfo = new ShapeDistributionInformation();
weight = 0;
return(false);
}
if (removedWeight > 0)
{
Vector3.Divide(ref removedCenter, removedWeight, out removedCenter);
}
//Compute the contributions from the original shape to the new form of the original collidable.
distributionInfo = new ShapeDistributionInformation();
weight = 0;
for (int i = compound.children.count - 1; i >= 0; i--)
{
var child = compound.children.Elements[i];
var entry = child.Entry;
var contribution = childContributions[child.shapeIndex];
Vector3.Add(ref contribution.Center, ref entry.LocalTransform.Position, out contribution.Center);
Vector3.Multiply(ref contribution.Center, child.Entry.Weight, out contribution.Center);
Vector3.Add(ref contribution.Center, ref distributionInfo.Center, out distributionInfo.Center);
distributionInfo.Volume += contribution.Volume;
weight += entry.Weight;
}
//Average the center out.
Vector3.Divide(ref distributionInfo.Center, weight, out distributionInfo.Center);
//Note that the 'entry' is from the Shape, and so the translations are local to the shape's center.
//That is not technically the center of the new collidable- distributionInfo.Center is.
//Offset the child collidables by -distributionInfo.Center using their local offset.
Vector3 offset;
Vector3.Negate(ref distributionInfo.Center, out offset);
//Compute the unscaled inertia tensor.
for (int i = compound.children.count - 1; i >= 0; i--)
{
var child = compound.children.Elements[i];
var entry = child.Entry;
Vector3 transformedOffset;
Quaternion conjugate;
Quaternion.Conjugate(ref entry.LocalTransform.Orientation, out conjugate);
Vector3.Transform(ref offset, ref conjugate, out transformedOffset);
child.CollisionInformation.localPosition = transformedOffset;
var contribution = childContributions[child.shapeIndex];
CompoundShape.TransformContribution(ref entry.LocalTransform, ref distributionInfo.Center, ref contribution.VolumeDistribution, entry.Weight, out contribution.VolumeDistribution);
//Vector3.Add(ref entry.LocalTransform.Position, ref offsetA, out entry.LocalTransform.Position);
Matrix3X3.Add(ref contribution.VolumeDistribution, ref distributionInfo.VolumeDistribution, out distributionInfo.VolumeDistribution);
}
//Normalize the volume distribution.
Matrix3X3.Multiply(ref distributionInfo.VolumeDistribution, 1 / weight, out distributionInfo.VolumeDistribution);
//Update the hierarchies of the compounds.
//TODO: Create a new method that does this quickly without garbage. Requires a new Reconstruct method which takes a pool which stores the appropriate node types.
compound.hierarchy.Tree.Reconstruct(compound.children);
return(true);
}
