Work with nParticle collisions

When nParticles are created or emitted into a scene, they are capable of colliding with other nParticle, nCloth, or passive objects that are assigned to the same Nucleus solver. They are also cable of colliding with each other by self-colliding. The nParticle object’s Collisions attributes determine how the nParticles behave when they collide with other Nucleus objects.

If you want to disable collisions between your nParticle object and specific Nucleus objects, you can set collisions layers or use Disable Collisions or Exclude Collide Pairs constraint. See Create an nParticle Disable Collision constraint and Create an nParticle Exclude Collide Pairs constraint.

You can use the Particle Collision Event Editor to create and edit nParticle collision events. See Create particle collision events.

To edit nParticle Collisions attributes

1. Select the nParticle object for which you want to edit Collisions attributes.
2. In the Attribute Editor click the nParticleShape tab.
3. To disable or dampen nParticle collisions and self collisions, in the Collisions section of the Attribute Editor, do the following:
   • Turn off Collide to disable collisions between the nParticle object and other Nucleus objects. See nParticle Collisions attributes.
   • Turn off Self Collide to disable nParticle self-collisions.
   • Set Collide Strength to specify if your nParticles fully or partially collide with other Nucleus objects.

     At the default value of 1, the nParticles fully collide with other Nucleus objects. Collide Strength values between 0 and 1 dampen the full collision, while 0 turns off nParticle collisions (which is the same as turning off the Collide attribute).

     You can also set Collide Strength on a per-particle basis using a Collide Strength Scale ramp.

4. To adjust the thickness of your nParticle object’s collision volumes, do the following:
   • Adjust the thickness of the collision volume between your nParticle object and other Nucleus objects it collides with by setting Collide Width Scale.
   • Adjust the thickness of the collision volume between an nParticle object's self-colliding particles by setting Self Collide Width Scale.
5. Edit the Collisions property values to adjust the basic behavior of your nParticles:
   • Adjust Bounce to increase or decrease the nParticles' bounciness or their amount of deflection on collision.
   • Adjust Friction to increase or decrease the amount the nParticles resist relative motion on collision.
   • Adjust Stickiness to increase or decrease the tendency of the nParticles to stick to other Nucleus objects on collision.

Setting Collision Layers

You can specify whether or not certain nParticle, nCloth, and passive collision objects that are part of the same Maya Nucleus system collide with each other by using collision layers. The Collision Layer attribute on your nParticleShape node determines on which collision layer each nParticle, nCloth, and passive object is placed, and the Collision Layer Range attribute on your nucleus node determines how nParticle, nCloth, and passive collision objects on different layers collide.

Note: nCloth and passive collision objects in collision layers only collide with nParticle objects that are in the same collision layer, or in layers of higher value.