public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var contact = contacts[i];
// update contact basis:
contact.CalculateBasis(velocities[contact.entityA] - velocities[contact.entityB]);
// update contact masses:
int aMaterialIndex = particleMaterialIndices[contact.entityA];
int bMaterialIndex = particleMaterialIndices[contact.entityB];
bool rollingContacts = (aMaterialIndex >= 0 ? collisionMaterials[aMaterialIndex].rollingContacts > 0 : false) |
(bMaterialIndex >= 0 ? collisionMaterials[bMaterialIndex].rollingContacts > 0 : false);
contact.CalculateContactMassesA(ref invMasses, ref prevPositions, ref prevOrientations, ref invInertiaTensors, rollingContacts);
contact.CalculateContactMassesB(ref invMasses, ref prevPositions, ref prevOrientations, ref invInertiaTensors, rollingContacts);
// update contact distance:
float dAB = math.dot(prevPositions[contact.entityA] - prevPositions[contact.entityB], contact.normal);
float dA = BurstMath.EllipsoidRadius(contact.normal, prevOrientations[contact.entityA], radii[contact.entityA].xyz);
float dB = BurstMath.EllipsoidRadius(contact.normal, prevOrientations[contact.entityB], radii[contact.entityB].xyz);
contact.distance = dAB - (dA + dB);
contacts[i] = contact;
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var pair = pairs[i];
float restVolumeA = 1.0f / invMasses[pair.particleA] / restDensities[pair.particleA];
float restVolumeB = 1.0f / invMasses[pair.particleB] / restDensities[pair.particleB];
// XSPH viscosity:
float viscosityCoeff = math.min(viscosities[pair.particleA], viscosities[pair.particleB]);
float4 relVelocity = velocities[pair.particleB] - velocities[pair.particleA];
float4 viscosity = viscosityCoeff * relVelocity * pair.avgKernel;
velocities[pair.particleA] += viscosity * restVolumeB;
velocities[pair.particleB] -= viscosity * restVolumeA;
// calculate vorticity:
float4 vgrad = pair.gradient * pair.avgGradient;
float4 vorticity = new float4(math.cross(relVelocity.xyz, vgrad.xyz), 0);
vorticities[pair.particleA] += vorticity * restVolumeB;
vorticities[pair.particleB] += vorticity * restVolumeA;
// calculate color field normal:
float radius = (radii[pair.particleA] + radii[pair.particleB]) * 0.5f;
normals[pair.particleA] += vgrad * radius / invMasses[pair.particleB] / fluidData[pair.particleB][0];
normals[pair.particleB] -= vgrad * radius / invMasses[pair.particleA] / fluidData[pair.particleA][0];
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var pair = pairs[i];
float restVolumeA = 1.0f / invMasses[pair.particleA] / restDensities[pair.particleA];
float restVolumeB = 1.0f / invMasses[pair.particleB] / restDensities[pair.particleB];
float gradA = restVolumeB * pair.avgGradient;
float gradB = restVolumeA * pair.avgGradient;
float vA = restVolumeB / restVolumeA;
float vB = restVolumeA / restVolumeB;
// accumulate pbf data (density, gradients):
fluidData[pair.particleA] += new float4(vA * pair.avgKernel, 0, gradA, gradA * gradA);
fluidData[pair.particleB] += new float4(vB * pair.avgKernel, 0, gradB, gradB * gradB);
// property diffusion:
float diffusionSpeed = (diffusion[pair.particleA] + diffusion[pair.particleB]) * pair.avgKernel * dt;
float4 userDelta = (userData[pair.particleB] - userData[pair.particleA]) * diffusionSpeed;
userData[pair.particleA] += vA * userDelta;
userData[pair.particleB] -= vB * userDelta;
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
int simplexStartA = simplexCounts.GetSimplexStartAndSize(contacts[i].bodyA, out int simplexSizeA);
int simplexStartB = simplexCounts.GetSimplexStartAndSize(contacts[i].bodyB, out int simplexSizeB);
for (int j = 0; j < simplexSizeA; ++j)
{
int particleIndex = simplices[simplexStartA + j];
BurstConstraintsBatchImpl.ApplyPositionDelta(particleIndex, constraintParameters.SORFactor, ref positions, ref deltas, ref counts);
BurstConstraintsBatchImpl.ApplyOrientationDelta(particleIndex, constraintParameters.SORFactor, ref orientations, ref orientationDeltas, ref orientationCounts);
}
for (int j = 0; j < simplexSizeB; ++j)
{
int particleIndex = simplices[simplexStartB + j];
BurstConstraintsBatchImpl.ApplyPositionDelta(particleIndex, constraintParameters.SORFactor, ref positions, ref deltas, ref counts);
BurstConstraintsBatchImpl.ApplyOrientationDelta(particleIndex, constraintParameters.SORFactor, ref orientations, ref orientationDeltas, ref orientationCounts);
}
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
BurstConstraintsBatchImpl.ApplyPositionDelta(contacts[i].entityA, constraintParameters.SORFactor, ref positions, ref deltas, ref counts);
BurstConstraintsBatchImpl.ApplyPositionDelta(contacts[i].entityB, constraintParameters.SORFactor, ref positions, ref deltas, ref counts);
BurstConstraintsBatchImpl.ApplyOrientationDelta(contacts[i].entityA, constraintParameters.SORFactor, ref orientations, ref orientationDeltas, ref orientationCounts);
BurstConstraintsBatchImpl.ApplyOrientationDelta(contacts[i].entityB, constraintParameters.SORFactor, ref orientations, ref orientationDeltas, ref orientationCounts);
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var pair = pairs[i];
float4 vgrad = pair.gradient * pair.avgGradient;
eta[pair.particleA] += math.length(vorticities[pair.particleA]) * vgrad / invMasses[pair.particleB] / restDensities[pair.particleB];
eta[pair.particleB] -= math.length(vorticities[pair.particleB]) * vgrad / invMasses[pair.particleA] / restDensities[pair.particleA];
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var contact = contacts[i];
int indexA = contact.entityA;
int indexB = contact.entityB;
// Combine collision materials:
BurstCollisionMaterial material = CombineCollisionMaterials(indexA, indexB);
// Calculate relative velocity:
float4 relativeVelocity = GetRelativeVelocity(indexA, indexB);
// Determine adhesion impulse magnitude:
float adhesionImpulse = contact.SolveAdhesion(material.stickDistance, material.stickiness, dt);
// Determine depenetration impulse magnitude:
float depenetrationImpulse = contact.SolvePenetration(relativeVelocity, solverParameters.maxDepenetration, dt);
float totalImpulse = depenetrationImpulse + adhesionImpulse;
// Apply normal impulse to both particles (w/ shock propagation):
if (math.abs(totalImpulse) > BurstMath.epsilon)
{
float shock = solverParameters.shockPropagation * math.dot(contact.normal, math.normalizesafe(gravity));
float4 delta = totalImpulse * dt * -contact.normal;
deltas[indexA] += delta * contact.normalInvMassA * (1 - shock);
deltas[indexB] -= delta * contact.normalInvMassB * (1 + shock);
counts[indexA]++;
counts[indexB]++;
}
// Apply position deltas immediately, if using sequential evaluation:
if (constraintParameters.evaluationOrder == Oni.ConstraintParameters.EvaluationOrder.Sequential)
{
ApplyPositionDelta(indexA, constraintParameters.SORFactor, ref positions, ref deltas, ref counts);
ApplyPositionDelta(indexB, constraintParameters.SORFactor, ref positions, ref deltas, ref counts);
}
contacts[i] = contact;
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var pair = pairs[i];
float4 distanceA = renderablePositions[pair.particleB] - smoothPositions[pair.particleA];
float4 distanceB = renderablePositions[pair.particleA] - smoothPositions[pair.particleB];
anisotropies[pair.particleA] += BurstMath.multrnsp(distanceA, distanceA) * pair.avgKernel;
anisotropies[pair.particleB] += BurstMath.multrnsp(distanceB, distanceB) * pair.avgKernel;
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var pair = pairs[i];
float4 gradient = (renderablePositions[pair.particleA] - renderablePositions[pair.particleB]);
float distance = math.length(gradient);
pair.avgKernel = (densityKernel.W(distance, radii[pair.particleA]) +
densityKernel.W(distance, radii[pair.particleB])) * 0.5f;
smoothPositions[pair.particleA] += new float4(renderablePositions[pair.particleB].xyz, 1) * pair.avgKernel;
smoothPositions[pair.particleB] += new float4(renderablePositions[pair.particleA].xyz, 1) * pair.avgKernel;
pairs[i] = pair;
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var pair = pairs[i];
float restVolumeA = 1.0f / invMasses[pair.particleA] / restDensities[pair.particleA];
float restVolumeB = 1.0f / invMasses[pair.particleB] / restDensities[pair.particleB];
// calculate tensile instability correction factor:
float wAvg = pair.avgKernel / ((densityKernel.W(0, radii[pair.particleA]) + densityKernel.W(0, radii[pair.particleB])) * 0.5f);
float scorrA = -(0.001f + 0.2f * surfaceTension[pair.particleA]) * wAvg / (invMasses[pair.particleA] * fluidData[pair.particleA][3]);
float scorrB = -(0.001f + 0.2f * surfaceTension[pair.particleB]) * wAvg / (invMasses[pair.particleB] * fluidData[pair.particleB][3]);
// calculate position delta:
float4 delta = pair.gradient * pair.avgGradient * ((fluidData[pair.particleA][1] + scorrA) * restVolumeB + (fluidData[pair.particleB][1] + scorrB) * restVolumeA) * sorFactor;
positions[pair.particleA] += delta * invMasses[pair.particleA];
positions[pair.particleB] -= delta * invMasses[pair.particleB];
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var contact = contacts[i];
int simplexStartA = simplexCounts.GetSimplexStartAndSize(contact.bodyA, out int simplexSizeA);
int simplexStartB = simplexCounts.GetSimplexStartAndSize(contact.bodyB, out int simplexSizeB);
// Combine collision materials:
BurstCollisionMaterial material = CombineCollisionMaterials(simplices[simplexStartA], simplices[simplexStartB]);
float4 simplexPositionA = float4.zero, simplexPositionB = float4.zero;
float simplexRadiusA = 0, simplexRadiusB = 0;
for (int j = 0; j < simplexSizeA; ++j)
{
int particleIndex = simplices[simplexStartA + j];
simplexPositionA += positions[particleIndex] * contact.pointA[j];
simplexRadiusA += BurstMath.EllipsoidRadius(contact.normal, orientations[particleIndex], radii[particleIndex].xyz) * contact.pointA[j];
}
for (int j = 0; j < simplexSizeB; ++j)
{
int particleIndex = simplices[simplexStartB + j];
simplexPositionB += positions[particleIndex] * contact.pointB[j];
simplexRadiusB += BurstMath.EllipsoidRadius(contact.normal, orientations[particleIndex], radii[particleIndex].xyz) * contact.pointA[j];
}
float4 posA = simplexPositionA - contact.normal * simplexRadiusA;
float4 posB = simplexPositionB + contact.normal * simplexRadiusB;
// adhesion:
float lambda = contact.SolveAdhesion(posA, posB, material.stickDistance, material.stickiness, substepTime);
// depenetration:
lambda += contact.SolvePenetration(posA, posB, solverParameters.maxDepenetration * substepTime);
// Apply normal impulse to both particles (w/ shock propagation):
if (math.abs(lambda) > BurstMath.epsilon)
{
float shock = solverParameters.shockPropagation * math.dot(contact.normal, math.normalizesafe(gravity));
float4 delta = lambda * contact.normal;
float baryScale = BurstMath.BaryScale(contact.pointA);
for (int j = 0; j < simplexSizeA; ++j)
{
int particleIndex = simplices[simplexStartA + j];
deltas[particleIndex] += delta * invMasses[particleIndex] * contact.pointA[j] * baryScale * (1 - shock);
counts[particleIndex]++;
}
baryScale = BurstMath.BaryScale(contact.pointB);
for (int j = 0; j < simplexSizeB; ++j)
{
int particleIndex = simplices[simplexStartB + j];
deltas[particleIndex] -= delta * invMasses[particleIndex] * contact.pointB[j] * baryScale * (1 + shock);
counts[particleIndex]++;
}
}
// Apply position deltas immediately, if using sequential evaluation:
if (constraintParameters.evaluationOrder == Oni.ConstraintParameters.EvaluationOrder.Sequential)
{
for (int j = 0; j < simplexSizeA; ++j)
{
int particleIndex = simplices[simplexStartA + j];
BurstConstraintsBatchImpl.ApplyPositionDelta(particleIndex, constraintParameters.SORFactor, ref positions, ref deltas, ref counts);
}
for (int j = 0; j < simplexSizeB; ++j)
{
int particleIndex = simplices[simplexStartB + j];
BurstConstraintsBatchImpl.ApplyPositionDelta(particleIndex, constraintParameters.SORFactor, ref positions, ref deltas, ref counts);
}
}
contacts[i] = contact;
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var contact = contacts[i];
int simplexStartA = simplexCounts.GetSimplexStartAndSize(contact.bodyA, out int simplexSizeA);
int simplexStartB = simplexCounts.GetSimplexStartAndSize(contact.bodyB, out int simplexSizeB);
float4 simplexVelocityA = float4.zero;
float4 simplexPrevPositionA = float4.zero;
quaternion simplexPrevOrientationA = new quaternion(0, 0, 0, 0);
float simplexRadiusA = 0;
float simplexInvMassA = 0;
float4 simplexInvInertiaA = float4.zero;
float4 simplexVelocityB = float4.zero;
float4 simplexPrevPositionB = float4.zero;
quaternion simplexPrevOrientationB = new quaternion(0, 0, 0, 0);
float simplexRadiusB = 0;
float simplexInvMassB = 0;
float4 simplexInvInertiaB = float4.zero;
for (int j = 0; j < simplexSizeA; ++j)
{
int particleIndex = simplices[simplexStartA + j];
simplexVelocityA += velocities[particleIndex] * contact.pointA[j];
simplexPrevPositionA += prevPositions[particleIndex] * contact.pointA[j];
simplexPrevOrientationA.value += prevOrientations[particleIndex].value * contact.pointA[j];
simplexInvMassA += invMasses[particleIndex] * contact.pointA[j];
simplexInvInertiaA += invInertiaTensors[particleIndex] * contact.pointA[j];
simplexRadiusA += BurstMath.EllipsoidRadius(contact.normal, prevOrientations[particleIndex], radii[particleIndex].xyz) * contact.pointA[j];
}
for (int j = 0; j < simplexSizeB; ++j)
{
int particleIndex = simplices[simplexStartB + j];
simplexVelocityB += velocities[particleIndex] * contact.pointB[j];
simplexPrevPositionB += prevPositions[particleIndex] * contact.pointB[j];
simplexPrevOrientationB.value += prevOrientations[particleIndex].value * contact.pointB[j];
simplexInvMassB += invMasses[particleIndex] * contact.pointB[j];
simplexInvInertiaB += invInertiaTensors[particleIndex] * contact.pointB[j];
simplexRadiusB += BurstMath.EllipsoidRadius(contact.normal, prevOrientations[particleIndex], radii[particleIndex].xyz) * contact.pointB[j];
}
// update contact distance
float dAB = math.dot(simplexPrevPositionA - simplexPrevPositionB, contact.normal);
contact.distance = dAB - (simplexRadiusA + simplexRadiusB);
// calculate contact points:
float4 contactPointA = simplexPrevPositionB + contact.normal * (contact.distance + simplexRadiusB);
float4 contactPointB = simplexPrevPositionA - contact.normal * (contact.distance + simplexRadiusA);
// update contact basis:
contact.CalculateBasis(simplexVelocityA - simplexVelocityB);
// update contact masses:
int aMaterialIndex = particleMaterialIndices[simplices[simplexStartA]];
int bMaterialIndex = particleMaterialIndices[simplices[simplexStartB]];
bool rollingContacts = (aMaterialIndex >= 0 ? collisionMaterials[aMaterialIndex].rollingContacts > 0 : false) |
(bMaterialIndex >= 0 ? collisionMaterials[bMaterialIndex].rollingContacts > 0 : false);
contact.CalculateContactMassesA(simplexInvMassA, simplexInvInertiaA, simplexPrevPositionA, simplexPrevOrientationA, contactPointA, rollingContacts);
contact.CalculateContactMassesB(simplexInvMassB, simplexInvInertiaB, simplexPrevPositionB, simplexPrevOrientationB, contactPointB, rollingContacts);
contacts[i] = contact;
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var contact = contacts[i];
int simplexStartA = simplexCounts.GetSimplexStartAndSize(contact.bodyA, out int simplexSizeA);
int simplexStartB = simplexCounts.GetSimplexStartAndSize(contact.bodyB, out int simplexSizeB);
// Combine collision materials:
BurstCollisionMaterial material = CombineCollisionMaterials(simplices[simplexStartA], simplices[simplexStartB]);
float4 prevPositionA = float4.zero;
float4 linearVelocityA = float4.zero;
float4 angularVelocityA = float4.zero;
float4 invInertiaTensorA = float4.zero;
quaternion orientationA = new quaternion(0, 0, 0, 0);
float simplexRadiusA = 0;
float4 prevPositionB = float4.zero;
float4 linearVelocityB = float4.zero;
float4 angularVelocityB = float4.zero;
float4 invInertiaTensorB = float4.zero;
quaternion orientationB = new quaternion(0, 0, 0, 0);
float simplexRadiusB = 0;
for (int j = 0; j < simplexSizeA; ++j)
{
int particleIndex = simplices[simplexStartA + j];
prevPositionA += prevPositions[particleIndex] * contact.pointA[j];
linearVelocityA += BurstIntegration.DifferentiateLinear(positions[particleIndex], prevPositions[particleIndex], substepTime) * contact.pointA[j];
angularVelocityA += BurstIntegration.DifferentiateAngular(orientations[particleIndex], prevOrientations[particleIndex], substepTime) * contact.pointA[j];
invInertiaTensorA += invInertiaTensors[particleIndex] * contact.pointA[j];
orientationA.value += orientations[particleIndex].value * contact.pointA[j];
simplexRadiusA += BurstMath.EllipsoidRadius(contact.normal, prevOrientations[particleIndex], radii[particleIndex].xyz) * contact.pointA[j];
}
for (int j = 0; j < simplexSizeB; ++j)
{
int particleIndex = simplices[simplexStartB + j];
prevPositionB += prevPositions[particleIndex] * contact.pointB[j];
linearVelocityB += BurstIntegration.DifferentiateLinear(positions[particleIndex], prevPositions[particleIndex], substepTime) * contact.pointB[j];
angularVelocityB += BurstIntegration.DifferentiateAngular(orientations[particleIndex], prevOrientations[particleIndex], substepTime) * contact.pointB[j];
invInertiaTensorB += invInertiaTensors[particleIndex] * contact.pointB[j];
orientationB.value += orientations[particleIndex].value * contact.pointB[j];
simplexRadiusB += BurstMath.EllipsoidRadius(contact.normal, prevOrientations[particleIndex], radii[particleIndex].xyz) * contact.pointB[j];
}
float4 rA = float4.zero, rB = float4.zero;
// Consider angular velocities if rolling contacts are enabled:
if (material.rollingContacts > 0)
{
rA = -contact.normal * simplexRadiusA;
rB = contact.normal * simplexRadiusB;
linearVelocityA += new float4(math.cross(angularVelocityA.xyz, rA.xyz), 0);
linearVelocityB += new float4(math.cross(angularVelocityB.xyz, rB.xyz), 0);
}
// Calculate relative velocity:
float4 relativeVelocity = linearVelocityA - linearVelocityB;
// Calculate friction impulses (in the tangent and bitangent ddirections):
float2 impulses = contact.SolveFriction(relativeVelocity, material.staticFriction, material.dynamicFriction, substepTime);
// Apply friction impulses to both particles:
if (math.abs(impulses.x) > BurstMath.epsilon || math.abs(impulses.y) > BurstMath.epsilon)
{
float4 tangentImpulse = impulses.x * contact.tangent;
float4 bitangentImpulse = impulses.y * contact.bitangent;
float4 totalImpulse = tangentImpulse + bitangentImpulse;
float baryScale = BurstMath.BaryScale(contact.pointA);
for (int j = 0; j < simplexSizeA; ++j)
{
int particleIndex = simplices[simplexStartA + j];
deltas[particleIndex] += (tangentImpulse * contact.tangentInvMassA + bitangentImpulse * contact.bitangentInvMassA) * substepTime * contact.pointA[j] * baryScale;
counts[particleIndex]++;
}
baryScale = BurstMath.BaryScale(contact.pointB);
for (int j = 0; j < simplexSizeB; ++j)
{
int particleIndex = simplices[simplexStartB + j];
deltas[particleIndex] -= (tangentImpulse * contact.tangentInvMassB + bitangentImpulse * contact.bitangentInvMassB) * substepTime * contact.pointB[j] * baryScale;
counts[particleIndex]++;
}
// Rolling contacts:
if (material.rollingContacts > 0)
{
// Calculate angular velocity deltas due to friction impulse:
float4x4 solverInertiaA = BurstMath.TransformInertiaTensor(invInertiaTensorA, orientationA);
float4x4 solverInertiaB = BurstMath.TransformInertiaTensor(invInertiaTensorB, orientationB);
float4 angVelDeltaA = math.mul(solverInertiaA, new float4(math.cross(rA.xyz, totalImpulse.xyz), 0));
float4 angVelDeltaB = -math.mul(solverInertiaB, new float4(math.cross(rB.xyz, totalImpulse.xyz), 0));
// Final angular velocities, after adding the deltas:
angularVelocityA += angVelDeltaA;
angularVelocityB += angVelDeltaB;
// Calculate weights (inverse masses):
float invMassA = math.length(math.mul(solverInertiaA, math.normalizesafe(angularVelocityA)));
float invMassB = math.length(math.mul(solverInertiaB, math.normalizesafe(angularVelocityB)));
// Calculate rolling axis and angular velocity deltas:
float4 rollAxis = float4.zero;
float rollingImpulse = contact.SolveRollingFriction(angularVelocityA, angularVelocityB, material.rollingFriction, invMassA, invMassB, ref rollAxis);
angVelDeltaA += rollAxis * rollingImpulse * invMassA;
angVelDeltaB -= rollAxis * rollingImpulse * invMassB;
// Apply orientation deltas to particles:
quaternion orientationDeltaA = BurstIntegration.AngularVelocityToSpinQuaternion(orientationA, angVelDeltaA, substepTime);
quaternion orientationDeltaB = BurstIntegration.AngularVelocityToSpinQuaternion(orientationB, angVelDeltaB, substepTime);
for (int j = 0; j < simplexSizeA; ++j)
{
int particleIndex = simplices[simplexStartA + j];
quaternion qA = orientationDeltas[particleIndex];
qA.value += orientationDeltaA.value;
orientationDeltas[particleIndex] = qA;
orientationCounts[particleIndex]++;
}
for (int j = 0; j < simplexSizeB; ++j)
{
int particleIndex = simplices[simplexStartB + j];
quaternion qB = orientationDeltas[particleIndex];
qB.value += orientationDeltaB.value;
orientationDeltas[particleIndex] = qB;
orientationCounts[particleIndex]++;
}
}
}
contacts[i] = contact;
}
}
public void Execute(int workItemIndex)
{
int start, end;
batchData.GetConstraintRange(workItemIndex, out start, out end);
for (int i = start; i < end; ++i)
{
var contact = contacts[i];
int indexA = contact.entityA;
int indexB = contact.entityB;
// Combine collision materials:
BurstCollisionMaterial material = CombineCollisionMaterials(contact.entityA, contact.entityB);
// Calculate relative velocity:
float4 angularVelocityA = float4.zero, angularVelocityB = float4.zero, rA = float4.zero, rB = float4.zero;
float4 relativeVelocity = GetRelativeVelocity(indexA, indexB, ref contact, ref angularVelocityA, ref angularVelocityB, ref rA, ref rB, material.rollingContacts > 0);
// Calculate friction impulses (in the tangent and bitangent ddirections):
float2 impulses = contact.SolveFriction(relativeVelocity, material.staticFriction, material.dynamicFriction, dt);
// Apply friction impulses to both particles:
if (math.abs(impulses.x) > BurstMath.epsilon || math.abs(impulses.y) > BurstMath.epsilon)
{
float4 tangentImpulse = impulses.x * contact.tangent;
float4 bitangentImpulse = impulses.y * contact.bitangent;
float4 totalImpulse = tangentImpulse + bitangentImpulse;
deltas[indexA] += (tangentImpulse * contact.tangentInvMassA + bitangentImpulse * contact.bitangentInvMassA) * dt;
deltas[indexB] -= (tangentImpulse * contact.tangentInvMassB + bitangentImpulse * contact.bitangentInvMassB) * dt;
counts[indexA]++;
counts[indexB]++;
// Rolling contacts:
if (material.rollingContacts > 0)
{
// Calculate angular velocity deltas due to friction impulse:
float4x4 solverInertiaA = BurstMath.TransformInertiaTensor(invInertiaTensors[indexA], orientations[indexA]);
float4x4 solverInertiaB = BurstMath.TransformInertiaTensor(invInertiaTensors[indexB], orientations[indexB]);
float4 angVelDeltaA = math.mul(solverInertiaA, new float4(math.cross(rA.xyz, totalImpulse.xyz), 0));
float4 angVelDeltaB = -math.mul(solverInertiaB, new float4(math.cross(rB.xyz, totalImpulse.xyz), 0));
// Final angular velocities, after adding the deltas:
angularVelocityA += angVelDeltaA;
angularVelocityB += angVelDeltaB;
// Calculate weights (inverse masses):
float invMassA = math.length(math.mul(solverInertiaA, math.normalizesafe(angularVelocityA)));
float invMassB = math.length(math.mul(solverInertiaB, math.normalizesafe(angularVelocityB)));
// Calculate rolling axis and angular velocity deltas:
float4 rollAxis = float4.zero;
float rollingImpulse = contact.SolveRollingFriction(angularVelocityA, angularVelocityB, material.rollingFriction, invMassA, invMassB, ref rollAxis);
angVelDeltaA += rollAxis * rollingImpulse * invMassA;
angVelDeltaB -= rollAxis * rollingImpulse * invMassB;
// Apply orientation deltas to particles:
quaternion orientationDeltaA = BurstIntegration.AngularVelocityToSpinQuaternion(orientations[indexA], angVelDeltaA);
quaternion orientationDeltaB = BurstIntegration.AngularVelocityToSpinQuaternion(orientations[indexB], angVelDeltaB);
quaternion qA = orientationDeltas[indexA];
qA.value += orientationDeltaA.value * dt;
orientationDeltas[indexA] = qA;
orientationCounts[indexA]++;
quaternion qB = orientationDeltas[indexB];
qB.value += orientationDeltaB.value * dt;
orientationDeltas[indexB] = qB;
orientationCounts[indexB]++;
}
}
contacts[i] = contact;
}
}