public void Execute(int index)
{
int i = activeParticles[index];
// the previous position/orientation is the current position/orientation at the start of the step.
previousPositions[i] = positions[i];
previousOrientations[i] = orientations[i];
if (inverseMasses[i] > 0)
{
float4 effectiveGravity = gravity;
// Adjust gravity for buoyant fluid particles:
if ((phases[i] & (int)Oni.ParticleFlags.Fluid) != 0)
{
effectiveGravity *= -buoyancies[i];
}
// apply external forces and gravity:
float4 vel = velocities[i] + (inverseMasses[i] * externalForces[i] + effectiveGravity) * deltaTime;
// project velocity to 2D plane if needed:
if (is2D)
{
vel[3] = 0;
}
velocities[i] = vel;
}
if (inverseRotationalMasses[i] > 0)
{
// apply external torques (simplification: we don't use full inertia tensor here)
float4 angularVel = angularVelocities[i] + inverseRotationalMasses[i] * externalTorques[i] * deltaTime;
// project angular velocity to 2D plane normal if needed:
if (is2D)
{
angularVel = angularVel.project(new float4(0, 0, 1, 0));
}
angularVelocities[i] = angularVel;
}
// integrate velocities:
positions[i] = BurstIntegration.IntegrateLinear(positions[i], velocities[i], deltaTime);
orientations[i] = BurstIntegration.IntegrateAngular(orientations[i], angularVelocities[i], deltaTime);
}
