Daemon Falloffs: Basics

Owned by thomas (Unlicensed)
Last updated: 08 Nov, 2016
3 min read

Most of RealFlow's force-based daemons provide a falloff function for controlling how the force should vanish.

Creating a Rigid Body Setup

Let's create a basic falloff scenario with a simple rigid body dynamics scene. Here is the setup – the nodes can be added from the appropriate shelves:

  • The ground object is a → passive rigid body.
  • Add a cube object and keep it selected,
  • Open Tools shelf > Array Tool, enter a value of 15 for the horizontal (depends on your → axis setup) “Number of Items” parameters, and click on “OK”.




After a few moments you will see a MultiBody consisting of 225 cubes:

  • Delete the original cube.
  • Rescale the MultiBody with the R key and make it an → active rigid body under Node Params > Node > Dynamics.
  • Change the MultiBody's' mass under Node Params > Rigid body > Density > 200

 



  • A → “Gravity” daemon ties the cubes to the ground.


The → “Attractor” daemon is placed in the scene's centre and uses the falloff – all parameters are located under “Node Params”:

  • Attractor > Bounded > Yes
  • Rescale the daemon's viewport gizmo with the R key and include all cubes.
  • Attractor > Internal force > -200.0
  • Make the force field visible under Display Force Field > Show field > Yes.
  • All you can see is a green mess.
  • Get a better view with Display Force Field > Magnitude scale

 

 

All arrows have exactly the same length, because the force is acting with the same strength at each point:



Activating the Falloff

Enable the daemon's falloff – all parameters located under Node Params > Force Field Falloff:

  • Enable falloff > Yes
  • Display falloff > Yes
  • Falloff bounds > Sphere

 

Now, the arrows have different lengths and you can see two spheres (circles in 2D):




  • Inside the dashed sphere, the arrows are not affected by the falloff.
  • This means that here, the daemon's forces are acting with the adjusted “Internal strength” value.
  • Towards the outer sphere the arrows become smaller and smaller, indicating the falloff.

 

When you simulate you will recognize that the inner cubes are stronger affected than their counterparts near the daemon's boundary – this is the falloff's influence:


The falloff creates different zones of attraction (only the MultiBody is visible here).


  • Change the MultiBody's "Density” if necessary.
  • Play with “Falloff percent” to change the size of the falloff zone.
  • Set the “Falloff decay type” to “Quadratic” and “Cubic” and simulate again to see the difference.
  • The arrows show you immediately how the forces change with different settings.
  • Simulate.