Stopping Particle Emission

Owned by thomas (Unlicensed)
Last updated: 17 Aug, 2015
3 min read

One common question is how to stop the emission of new particles? There are several methods to do this.

HyFLIP

Defining a Volume

The relevant settings are located in the Hybrido emitter node under HY_Emitter node > Node Params > Emitter:

  • When “Stream” is set to “No” RealFlow creates a certain number of particles based on the shape of the object under Node Params > Emitter > Object. Once the simulation starts no more particles will be created. This mode is comparable to the  “Volume” option of the → Dyverso and → standard particle emitters.

 

Stream Animation

In simulations where “Stream” is set to “Yes” it is possible to animate the parameter:

 

 

  • Let's say the emission of particles should stop at frame 50.
  • Stream > Yes
  • Shift the timeline slider to frame 49.
  • Click on the dot next to the “Stream” parameter.
  • Go to frame 50, set “Stream” to “No”, and click again on the dot.
  • Right-click on “Stream” and choose “Open curve”. The “Curve Editor” is opened.
  • Select the two keys and click on “Set Selected Points Type to Stepped” (see image below).

 

 

Stream Expression

A very simple, yet effective method is to manage emission with an → expression:

  • Right-click on “Stream” and choose “Open curve”. The “Curve Editor” is opened.
  • In the empty field to the left of "Delete Expression" enter: if(f>49,0,1)
  • This expression says that if the current frame is greater than 49 the “Stream” option will be set from “Yes” to “No”.
  • These two states are represented as binary numbers here – 1 and 0.



Standard Particle Emitters

Defining a Volume

Similar to HyFLIP emitters, SPH-PBF some emitters let you define a certain volume that is filled with particles:

  • Emitter node > Node Params > emitter-specific section (e.g. “Circle”) > Volume
  • “Sphere” and “Fill Object” have a built-in fill option.

 

 

Speed Animation and Expressions

The next two methods are exactly the same as described under “HyFLIP” and use animation keys and an → expression. The only difference is that with SPH standard particle emitters the “Speed” parameter is animated and set to 0:

  • Emitter node > Node Params > emitter-specific section (e.g. “Circle”) > Speed

 

If you work with an expression, the two arguments are 0.0 and the emitter's current speed. By default, this is 2.0:

  • Right-click on “Stream” and choose “Open curve”. The “Curve Editor” is opened.
  • In the empty field to the left of "Delete Expression" enter: if(f>49,0.0,2.0)
  • This expression says that if the current frame is greater than 49 the “Speed” parameter will be set from 2.0 to 0.0.

 

 

Particle Limit

Another idea is to define a particle limit with

  • Emitter node > Node Params > Particles > Max Particles
  • Just enter a number, e.g. 75000, and the emitter will stop to create new particles once this limit has been reached (in most cases you get a few more particles).



Dyverso Emitters

With these fluid emitters you have exactly the same possibilities as shown under "Standard Particle Emitters" – only the "Particle Limit" method is not supported.