Creating and Applying a Force

You can create natural forces using the Force commands. You can apply any number of forces to ICE particles, hair objects, cloth objects, soft-body objects, and rigid bodies. As well, you can have the same force applied to a number of hair, cloth, or soft-body objects in a scene.

When you apply a force to a rigid body object, it is applied to the rigid body simulation environment. This makes the force have an effect on all elements in the rigid body simulation, but does not affect other simulation objects in the scene (such as hair) unless you explicitly apply it to them. See Applying Forces to Rigid Bodies for more information.

For information on how to apply forces to ICE particles, see ICE Forces [ICE Guide].

NoteIf you're applying a force to hair, make sure dynamics is first set on the hair (see Making Hair Move with Dynamics [Hair]).

You can apply a force to simulated objects (hair, soft bodies, and cloth) in one of two ways as described below: with the simulation object selected first or with the force created first.

To create and apply a force to the selected a simulation object

Select the object (hair, cloth, or soft-body object) to which you want to apply the force.

For rigid bodies, you don't need to select anything: just create the force and it is automatically added to the Forces group in the current simulation environment (see Applying Forces to Rigid Bodies).
Choose the force in one of these ways to automatically create and apply the force to the selected object:
- Get Force force name from the Simulate toolbar
  
  or
- Create Force force name from the Hair toolbar
  
  or
- Get Primitive Control Object force name from any other toolbar

The force control object appears in the viewports and its property editor opens. For example, if you selected the Attractor force, the Attractor property editor opens in which you can modify its strength, range of influence, and decay (falloff).

NoteYou can enter negative values for the Amplitude parameter for the many of the forces.

As you modify the force's attributes, its control object in the viewport updates accordingly to provide you with a visual cue as to its strength and/or range. Scaling the control object changes the Amplitude value accordingly.

To create a force and then apply it

With nothing selected, choose the force in one of these ways to first create the force object:
- Get Force force name from the Simulate toolbar.
  
  or
- Create Force force name from the Hair toolbar.
  
  or
- Get Primitive Control Object force name from any other toolbar.
The force control object appears and its property editor opens.
Select the objects (hair, cloth, or soft body object) to which you want to apply the force.
Do one of the following, according to the type of object that is selected:
- Choose Modify Cloth Apply Force from the Simulate toolbar.
  
  or
- Choose Modify Soft Body Apply Force from the Simulate toolbar.
  
  or
- Choose Modify Environment Apply Force from the Hair panel.
Pick the force object, then right-click to end your selection.

Naming Forces

You can name each force you create so that it's easy to tell them apart from each other. For example, if you have two different wind forces in a scene, one can be called "gale force" while the other is called "gentle breeze".

To name a force

Enter a descriptive name in the Name text box in each force's property editor.

Muting Forces

You can mute each force so that you can test and tweak the results of forces individually if you have multiple forces in a scene.

To mute a force

Select the Mute option in each force's property editor.

As well, you can animate the mute option to do such things as having a wind suddenly blow, then disappear.

When muted, the force's icon in the explorer has a little orange "m" over it.

Disconnecting Forces

You can easily disconnect forces from the simulation objects to which they're associated.

To disconnect a force

Selected the hair, cloth, or soft body object to which one or more forces is connected.
Do one of the following (this also works for hair):
- Choose Modify Cloth Disconnect Obstacle/Force/Emitter from the Simulate toolbar.
  
  or
- Choose Modify Soft Body Disconnect Obstacle/Force/Emitter from the Simulate toolbar.
Pick the forces you want to disconnect, then right-click to end the picking session.

NoteYou cannot disconnect a force for rigid bodies as you can for other simulations. You can, however, remove it from the Forces group in the simulation environment without deleting it or you can mute it.

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