Make tubes react to forces

There are two ways to make tubes react to forces:

• define Paint Effects brush forces
• apply forces to stroke control curves

Use brush settings to make tubes react to forces

You can make strokes react to forces such as gravity, deflection, and momentum by applying the settings under Tubes > Behavior > Forces. For details, see Forces brush settings. Keyframe these settings to make the tubes move dynamically in reaction to the forces.

You can also add turbulence to brushes. Simply turn turbulence on for a stroke, and Paint Effects automatically animates the reaction of the tubes.

To apply turbulence to brushes

1. Select the stroke.
2. In the Attribute Editor, expand Tubes > Behavior > Turbulence.
3. Change the Turbulence Type from off to any of the other options, then define the turbulence settings you want applied to the stroke tubes. For details, see Turbulence brush settings.
4. In the scene view, click the Play Forward button to check that the effect is as you want it. You can tweak the turbulence settings while playing.
   Tip:

   You can loop the brush animation smoothly. For details, see Loop brush animations.

Use control curves to make tubes react to forces

If you want stroke tubes to react to forces other than the forces available in the Paint Effects brushes (or in addition to), you can do so by creating control curves and making the control curves react to the forces in your scene. This is an effective technique, for example, for making long hair move naturally or for adding localized forces to trees.

To animate tube behavior by applying forces to control curves

1. Create the control curves. For details, see Modify tube behavior using control curves.
2. Select the stroke(s) you want controlled by the control curves and set the Curve Follow and/or Curve Attract to values for the stroke(s) to be other than 0.
3. Make the control curves into soft bodies as follows:
   • Select the control curves.
   • In the Dynamics menu set, select Soft/Rigid Bodies > Create Soft Body.
4. Add the desired force fields to the scene (for example, selectFields > Vortex) and position them to affect the control curves.
5. In the scene view, click the Play Forward button to check that the effect is as you want it.
6. Render the animation. See Create a composite of Paint Effects strokes and your scene.