//Loops:
void LateUpdate()
{
if (_particleSystem == null)
{
return;
}
if (_particles == null)
{
_particles = new ParticleSystem.Particle[_particleSystem.main.maxParticles];
}
int aliveParticlesCount = _particleSystem.GetParticles(_particles);
for (int i = 0; i < aliveParticlesCount; i++)
{
//get calculation pieces:
float seedMax = Mathf.Pow(10, _particles[i].randomSeed.ToString().Length);
float seedAsPercent = _particles[i].randomSeed / seedMax;
float travelPercentage = 1 - (_particles[i].remainingLifetime / _particles[i].startLifetime);
//bypass issue while running at edit time when particles haven't reached the spline end:
if (_spline.GetDirection(travelPercentage, false) == Vector3.zero)
{
continue;
}
//get a direction off our current point on the path - rotating by 1080 results in better distribution since Unity's randomSeed for particles favors lower numbers:
Vector3 offshootDirection = Quaternion.AngleAxis(1080 * seedAsPercent, -_spline.GetDirection(travelPercentage, false)) * _spline.Up(travelPercentage);
Vector3 previousOffshootDirection = Quaternion.AngleAxis(1080 * seedAsPercent, -_spline.GetDirection(travelPercentage - _previousDiff, false)) * _spline.Up(travelPercentage - _previousDiff, false);
//cache our positions:
Vector3 position = _spline.GetPosition(travelPercentage, false);
//cache a previous position for velocity if possible:
Vector3 lastPosition = position;
if (travelPercentage - .01f >= 0)
{
lastPosition = _spline.GetPosition(travelPercentage - _previousDiff, false);
}
//decide how far to offshoot from the spline based on where we are between the start and end radius:
float offset = Mathf.Lerp(startRadius, endRadius, travelPercentage);
float previousOffset = Mathf.Lerp(startRadius, endRadius, travelPercentage - _previousDiff);
//place particles depending on simulation space:
Vector3 currentPosition = Vector3.zero;
Vector3 previousPosition = Vector3.zero;
switch (_particleSystem.main.simulationSpace)
{
case ParticleSystemSimulationSpace.Local:
currentPosition = _particleSystem.transform.InverseTransformPoint(position + offshootDirection * offset);
previousPosition = _particleSystem.transform.InverseTransformPoint(lastPosition + previousOffshootDirection * previousOffset);
break;
case ParticleSystemSimulationSpace.World:
case ParticleSystemSimulationSpace.Custom:
currentPosition = position + offshootDirection * offset;
previousPosition = position + previousOffshootDirection * previousOffset;
break;
}
//apply:
_particles[i].position = currentPosition;
_particles[i].velocity = currentPosition - previousPosition;
}
//apply the particle changes back to the system:
_particleSystem.SetParticles(_particles, _particles.Length);
}
