private void ApplyTearing()
{
ObiDistanceConstraintBatch distanceBatch = DistanceConstraints.GetBatches()[0] as ObiDistanceConstraintBatch;
float[] forces = new float[distanceBatch.ConstraintCount];
Oni.GetBatchConstraintForces(distanceBatch.OniBatch, forces, distanceBatch.ConstraintCount, 0);
List <int> tearedEdges = new List <int>();
for (int i = 0; i < forces.Length; i++)
{
float p1Resistance = tearResistance[distanceBatch.springIndices[i * 2]];
float p2Resistance = tearResistance[distanceBatch.springIndices[i * 2 + 1]];
// average particle resistances:
float resistance = (p1Resistance + p2Resistance) * 0.5f * tearResistanceMultiplier;
if (-forces[i] * 1000 > resistance) // units are kilonewtons.
{
tearedEdges.Add(i);
}
}
if (tearedEdges.Count > 0)
{
DistanceConstraints.RemoveFromSolver(null);
for (int i = 0; i < tearedEdges.Count; i++)
{
Tear(tearedEdges[i]);
}
DistanceConstraints.AddToSolver(this);
// update active bending constraints:
BendingConstraints.SetActiveConstraints();
// update solver deformable triangle indices:
UpdateDeformableTriangles();
// upload active particle list to solver:
solver.UpdateActiveParticles();
}
}
/**
* Tears a cloth distance constraint, affecting both the physical representation of the cloth and its mesh.
*/
public void Tear(int constraintIndex)
{
if (topology == null)
{
return;
}
// don't allow splitting if there are no free particles left in the pool.
if (usedParticles >= sharedMesh.vertexCount + pooledVertices)
{
return;
}
// get involved constraint batches:
ObiDistanceConstraintBatch distanceBatch = (ObiDistanceConstraintBatch)DistanceConstraints.GetBatches()[0];
ObiBendConstraintBatch bendingBatch = (ObiBendConstraintBatch)BendingConstraints.GetBatches()[0];
// get particle indices at both ends of the constraint:
int splitIndex = distanceBatch.springIndices[constraintIndex * 2];
int intactIndex = distanceBatch.springIndices[constraintIndex * 2 + 1];
// we will split the particle with higher mass, so swap them if needed.
if (invMasses[splitIndex] > invMasses[intactIndex])
{
int aux = splitIndex;
splitIndex = intactIndex;
intactIndex = aux;
}
// Calculate the splitting plane in local space:
Vector3 v1 = transform.worldToLocalMatrix.MultiplyPoint3x4(solver.renderablePositions[particleIndices[splitIndex]]);
Vector3 v2 = transform.worldToLocalMatrix.MultiplyPoint3x4(solver.renderablePositions[particleIndices[intactIndex]]);
Vector3 normal = (v2 - v1).normalized;
int numUpdatedHalfEdges = maxVertexValency;
int[] updatedHalfEdges = new int[numUpdatedHalfEdges];
// Try to split the vertex at that particle.
// If we cannot not split the higher mass particle, try the other one. If that fails too, we cannot tear this edge.
if (invMasses[splitIndex] == 0 ||
!Oni.TearDeformableMeshAtVertex(deformableMesh, splitIndex, ref v1, ref normal, updatedHalfEdges, ref numUpdatedHalfEdges))
{
// Try to split the other particle:
int aux = splitIndex;
splitIndex = intactIndex;
intactIndex = aux;
v1 = transform.worldToLocalMatrix.MultiplyPoint3x4(solver.renderablePositions[particleIndices[splitIndex]]);
v2 = transform.worldToLocalMatrix.MultiplyPoint3x4(solver.renderablePositions[particleIndices[intactIndex]]);
normal = (v2 - v1).normalized;
if (invMasses[splitIndex] == 0 ||
!Oni.TearDeformableMeshAtVertex(deformableMesh, splitIndex, ref v1, ref normal, updatedHalfEdges, ref numUpdatedHalfEdges))
{
return;
}
}
// identify weak points around the cut:
int weakPt1 = -1;
int weakPt2 = -1;
float weakestValue = float.MaxValue;
float secondWeakestValue = float.MaxValue;
foreach (Oni.Vertex v in topology.GetNeighbourVerticesEnumerator(topology.heVertices[splitIndex]))
{
Vector3 neighbour = transform.worldToLocalMatrix.MultiplyPoint3x4(solver.renderablePositions[particleIndices[v.index]]);
float weakness = Mathf.Abs(Vector3.Dot(normal, (neighbour - v1).normalized));
if (weakness < weakestValue)
{
secondWeakestValue = weakestValue;
weakestValue = weakness;
weakPt2 = weakPt1;
weakPt1 = v.index;
}
else if (weakness < secondWeakestValue)
{
secondWeakestValue = weakness;
weakPt2 = v.index;
}
}
// reduce tear resistance at the weak spots of the cut, to encourage coherent tear formation.
if (weakPt1 >= 0)
{
tearResistance[weakPt1] *= 1 - tearDebilitation;
}
if (weakPt2 >= 0)
{
tearResistance[weakPt2] *= 1 - tearDebilitation;
}
topology.UpdateVertexCount();
// halve the mass and radius of the original particle:
invMasses[splitIndex] *= 2;
solidRadii[splitIndex] *= 0.5f;
// copy the new particle data in the actor and solver arrays:
positions[usedParticles] = positions[splitIndex];
velocities[usedParticles] = velocities[splitIndex];
active[usedParticles] = active[splitIndex];
invMasses[usedParticles] = invMasses[splitIndex];
solidRadii[usedParticles] = solidRadii[splitIndex];
phases[usedParticles] = phases[splitIndex];
areaContribution[usedParticles] = areaContribution[splitIndex];
tearResistance[usedParticles] = tearResistance[splitIndex];
restPositions[usedParticles] = positions[splitIndex];
restPositions[usedParticles][3] = 0; // activate rest position.
solver.activeParticles.Add(particleIndices[usedParticles]);
// update solver particle data:
Vector4[] velocity = { Vector4.zero };
Oni.GetParticleVelocities(solver.OniSolver, velocity, 1, particleIndices[splitIndex]);
Oni.SetParticleVelocities(solver.OniSolver, velocity, 1, particleIndices[usedParticles]);
Vector4[] position = { Vector4.zero };
Oni.GetParticlePositions(solver.OniSolver, position, 1, particleIndices[splitIndex]);
Oni.SetParticlePositions(solver.OniSolver, position, 1, particleIndices[usedParticles]);
Oni.SetParticleInverseMasses(solver.OniSolver, new float[] { invMasses[splitIndex] }, 1, particleIndices[usedParticles]);
Oni.SetParticleSolidRadii(solver.OniSolver, new float[] { solidRadii[splitIndex] }, 1, particleIndices[usedParticles]);
Oni.SetParticlePhases(solver.OniSolver, new int[] { phases[splitIndex] }, 1, particleIndices[usedParticles]);
usedParticles++;
// update distance constraints:
for (int i = 0; i < numUpdatedHalfEdges; ++i)
{
int halfEdgeIndex = updatedHalfEdges[i];
Oni.HalfEdge e = topology.heHalfEdges[halfEdgeIndex];
// find start and end vertex indices for this edge:
int startVertex = topology.GetHalfEdgeStartVertex(topology.heHalfEdges[halfEdgeIndex]);
int endVertex = topology.heHalfEdges[halfEdgeIndex].endVertex;
if (distanceConstraintMap[halfEdgeIndex] > -1) // update existing edge
{
distanceBatch.springIndices[distanceConstraintMap[halfEdgeIndex] * 2] = startVertex;
distanceBatch.springIndices[distanceConstraintMap[halfEdgeIndex] * 2 + 1] = endVertex;
}
else if (topology.IsSplit(halfEdgeIndex)) // new edge
{
int pairConstraintIndex = distanceConstraintMap[topology.heHalfEdges[halfEdgeIndex].pair];
// update constraint-edge map:
distanceConstraintMap[halfEdgeIndex] = distanceBatch.restLengths.Count;
// add the new constraint:
distanceBatch.AddConstraint(startVertex,
endVertex,
distanceBatch.restLengths[pairConstraintIndex],
distanceBatch.stiffnesses[pairConstraintIndex].x,
distanceBatch.stiffnesses[pairConstraintIndex].y);
}
// update deformable triangles:
if (e.indexInFace > -1)
{
deformableTriangles[e.face * 3 + e.indexInFace] = e.endVertex;
}
}
if (splitIndex < bendConstraintOffsets.Length - 1)
{
// deactivate bend constraints that contain the split vertex...
// ...at the center:
for (int i = bendConstraintOffsets[splitIndex]; i < bendConstraintOffsets[splitIndex + 1]; ++i)
{
bendingBatch.DeactivateConstraint(i);
}
// ...at one end:
foreach (Oni.Vertex v in topology.GetNeighbourVerticesEnumerator(topology.heVertices[splitIndex]))
{
if (v.index < bendConstraintOffsets.Length - 1)
{
for (int i = bendConstraintOffsets[v.index]; i < bendConstraintOffsets[v.index + 1]; ++i)
{
if (bendingBatch.bendingIndices[i * 3] == splitIndex || bendingBatch.bendingIndices[i * 3 + 1] == splitIndex)
{
bendingBatch.DeactivateConstraint(i);
}
}
}
}
}
// Create new aerodynamic constraint:
/*aerodynamicConstraints.AddConstraint(true,newParticle[0],
* Vector3.up,
* aerodynamicConstraints.windVector,
* areaContribution[newParticle[0]],
* aerodynamicConstraints.dragCoefficient,
* aerodynamicConstraints.liftCoefficient);*/
}