public void Execute()
{
for (int idA = 0; idA < length; idA++)
{
float3 predPosA = predPositions[idA].Value;
float massInvA = massesInv[idA].Value;
NativeArray <DistanceConstraintUni> cnstrsA = distanceConstraints[idA];
float3 delta = new float3(0, 0, 0);
int cnstrCount = 0;
for (int i = 0; i < 34; i++)
{
DistanceConstraintUni cnstr = cnstrsA[i];
if (cnstr.otherId == -1)
{
break;
}
float3 predPosB = predPositions[cnstr.otherId].Value;
float massInvB = massesInv[cnstr.otherId].Value;
float3 normal = predPosA - predPosB;
float length = math.length(normal.xyz);
float invMass = massInvA + massInvB;
if (invMass <= math.epsilon_normal || length <= math.epsilon_normal)
{
continue;
}
float3 dP = (1.0f / invMass) * (length - cnstr.restLength) * (normal / length) * stiffness;
delta -= dP * massInvA;
cnstrCount++;
}
predPositions[idA] = new PredictedPositions {
Value = predPosA + delta / cnstrCount
};
}
}
private void AddSoftbody(DefKit.TetMesh tetMesh)
{
int[] constraintsCounter = new int[tetMesh.pointsCount];
for (int i = 0; i < tetMesh.edgesCount; i++)
{
//bilateral constraints
Entity distanceConstraint = EntityManager.CreateEntity(typeof(DistanceConstraint));
EntityManager.SetComponentData(distanceConstraint, new DistanceConstraint
{
idA = tetMesh.edges[i].idA,
idB = tetMesh.edges[i].idB,
restLength = tetMesh.edges[i].restLength
});
constraintsCounter[tetMesh.edges[i].idA]++;
constraintsCounter[tetMesh.edges[i].idB]++;
}
int maxCount = 0;
for (int i = 0; i < tetMesh.pointsCount; i++)
{
maxCount = math.max(maxCount, constraintsCounter[i]);
constraintsCounter[i] = 0;
}
NativeArray <Entity> particles = new NativeArray <Entity>(tetMesh.pointsCount, Allocator.Temp);
EntityManager.CreateEntity(ParticleArchetype, particles);
for (int i = 0; i < tetMesh.pointsCount; i++)
{
EntityManager.SetComponentData(particles[i], new Position {
Value = tetMesh.nodesPositions[i]
});
EntityManager.SetComponentData(particles[i], new MassInv {
Value = 1
});
EntityManager.AddComponent(particles[i], ComponentType.FixedArray(typeof(DistanceConstraintUni), maxCount));
EntityManager.AddSharedComponentData(particles[i], ParticleLook);
//fill the arrays with -1s (end of entry marker)
NativeArray <DistanceConstraintUni> cnstrsArr = EntityManager.GetFixedArray <DistanceConstraintUni>(particles[i]);
for (int c = 0; c < maxCount; c++)
{
cnstrsArr[c] = new DistanceConstraintUni {
otherId = -1, restLength = 0
}
}
;
}
//unilateral constraints
for (int i = 0; i < tetMesh.edgesCount; i++)
{
int idA = tetMesh.edges[i].idA;
int idB = tetMesh.edges[i].idB;
float restLength = tetMesh.edges[i].restLength;
NativeArray <DistanceConstraintUni> cnstrsArrA = EntityManager.GetFixedArray <DistanceConstraintUni>(particles[idA]);
NativeArray <DistanceConstraintUni> cnstrsArrB = EntityManager.GetFixedArray <DistanceConstraintUni>(particles[idB]);
cnstrsArrA[constraintsCounter[idA]] = new DistanceConstraintUni {
otherId = idB, restLength = restLength
};
cnstrsArrB[constraintsCounter[idB]] = new DistanceConstraintUni {
otherId = idA, restLength = restLength
};
constraintsCounter[idA]++;
constraintsCounter[idB]++;
}
particles.Dispose();
}
