...
Particle shifting can also be done with the "Container" emitter and "Filter" daemon. With this built-in and ready-to-use combination you can achieve the same effect, but sometimes it is better to implement the transition from one emitter to another with a script:
| Code Block | ||||||
|---|---|---|---|---|---|---|
| ||||||
# Type this part to Simulation Events > Scene > ScenePre
# Initialize the container emitter before starting the simulation
source_emitter = scene.get_PB_Emitter("Source")
source_resolution = source_emitter.getParameter("Resolution")
container_emitter = scene.get_PB_Emitter("Container")
container_emitter.setParameter("Interpolation", "Local")
container_emitter.setParameter("Resolution",source_resolution)
container_emitter.setParameter("Speed", 0.0)
# Write this part to Simulation Events > Steps > StepsPre
velocity_threshold = 3.0
source_emitter = scene.get_PB_Emitter("Source")
container_emitter = scene.get_PB_Emitter("Container")
source_particle = source_emitter.getFirstParticle()
while (source_particle):
source_particle_vel = source_particle.getVelocity()
source_particle_magnitude = source_particle_vel.module()
source_particle_id = source_particle.getId()
if (source_particle_magnitude >= velocity_threshold):
source_particle_pos = source_particle.getPosition()
container_emitter.addParticle(source_particle_pos,source_particle_vel)
source_emitter.removeParticle(source_particle_id)
source_particle = source_particle.getNextParticle() |
...
Now, what is going on here? The basic structure and syntax should already be familiar, though there are few new functions. The very first part initializes the container emitter. You may remember that it is crucial that both emitters share equal resolution and the container’s speed must be 0.0. Equalizing the resolution is a pretty easy task, but it is recommended to change interpolation to local, as you perform a change of resolution. The script just reads out the resolution value from the source emitter and uses the result for the container. Resetting speed to 0.0 is even simpler, because you just have to set the parameter to the desired value. Here it would also be possible to insert an “if”-condition:
| Code Block | ||||||
|---|---|---|---|---|---|---|
| ||||||
container_emitter_speed = container_emitter.getParameter("Speed")
if (container_emitter_speed != 0.0):
container_emitter.setParameter("Speed", 0.0) |
...
Here, the magnitude of the velocity vector is used. The magnitude is not a vector, but a single floating number, which is much easier to handle and can be extracted with:
| Code Block | ||||
|---|---|---|---|---|
| ||||
source_particle_velocity = source_particle.getVelocity() source_velocity_magnitude = source_particle_velocity.module() |
...