nParticle Collisions

nParticles are capable of colliding with other nParticle or passive objects that are assigned to the same Nucleus solver. They are also capable of colliding with a virtual plane or each other by self-colliding.

nParticle Collision with a Ground Plane

1. Make an emitter and move it up the Y a few units.

2. Select the Nucleus in the Outliner

3. In the Attribute Editor, select the Ground Plane section and turn on Use Plane

4. Rewind the animation and Play (your emitter must be above the plane)

5. In the Nucleus adjust the following:

Bounce, Friction, Stickiness

nParticle Collision with other particles

1. Create a Polygon sphere and scale it up (we have had problems filling NURBS spheres)

2. Assign a Lambert Shader to the sphere and change the Transparency so you can see through it

3. With the sphere selected, go to the nParticle menu and select Fill Object Options

Note: Change all the settings to 0 for the Min and 1.0 for the Max.

4. You can change Resolution and Particle Density in the Options - Click Particle Fill

5. Delete the sphere so you have a ball of particles

6. Select the Nucleus and move it down below the particles

7. In the Nucleus Attribute Editor turn Ground Plane - Use Plane to ON and adjust Plane bounce, stickiness, and friction.

8. Rewind and Play - If it is not working, make sure Gravity is turned on.

Test 2

1. Turn OFF the Ground Plane and set Gravity to 0 and Air Density to 0 and any other settings to make them NOT move.

2. Make a new Directional Emitter using the same nucleus as the particle ball

3. With the emitter selected hit the t key (T)

4. Adjust the rate, direction and other parameters by pulling on the diamond (or other icon) then clicking the Circle with the line through it to get to a new parameter so the particles crash into the particle ball.

5. Rewind and Play

6. Select the nParticle object for which you want to edit Collisions attributes.

7. In the Attribute Editor click the nParticleShape tab.

Open the Collisions section

To disable or dampen nParticle collisions and self collisions, do the following:

Turn off Collide to disable collisions between the nParticle object and other Nucleus objects.

Turn off or on Self Collide to disable/enable nParticle self-collisions.

Set Collide Strength to specify if your nParticles fully or partially collide with other Nucleus objects.

1 = nParticles fully collide with other Nucleus objects.
Between 0 and 1 = dampens the full collision
0 = turns off nParticle collisions (which is the same as turning off the Collide attribute)

Collide Width Scale
To adjust the thickness of your nParticle object’s collision volumes

Bounce, Friction, Stickiness can be adjusted

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

Collide Strength Scale Input:

When off, the per-particle attributes are deleted. No effect.

The per-particle attribute values are determined by the nParticle’s age, which is based on the particle Lifespan mode.

Normalized Age
The per-particle attribute values are determined by the normalized age of the nParticle. To use Normalized Age, the nParticle object must have a defined lifespan. Set the Lifespan Mode attribute to Constant or Random range. The per-particle attribute values are mapped within the range of the nParticle object’s lifespan.

The per-particle attribute values are determined by nParticle speed.

The per-particle attribute values are determined by nParticle acceleration.

Particle ID
The per-particle attribute values are determined by the nParticle’s ID. Particle IDs are unique and generated at the beginning of the particle’s lifespan.

Randomizing ID
The per-particle attribute values are determined by a randomized nParticle ID.

Based on the size of the particle if it has a radius attribute associated with it.

Input Max
Sets the maximum value for the range used by the ramp.

Set the Initial State for each particle sets:

1. Rewind and play till you like how it looks then select Fields/Solvers - Initial State - Set for Selected

If you decide you don't like it, you can Initial State - Clear Initial State

nParticles and Geometry Collisions

Create and then select some geometry and then select the nCloth menu - Create Passive Collider

Create a directional emitter with some spread that points at the sphere. Make sure they are using the same nucleus.

Rewind and Play

Adjust the Collisions Attributes in the particleShape tab of the Attribute Editor

***NOTE: if you have more than one Nucleus, you will want to use the Passive Collider Options to select the correct one. Only particles effected by that Nucleus will bounce off the geometry.


Particle Collision Events

Make a New Directional Emitter and also a Plane (polygon or NURBS)

Move the emitter up in the Y direction to be above the plane

In the nParticleShape Attribute Editor, open - Dynamic Properties - and turn ON - Ignore Solver Wind and Ignore Solver Gravity (check mark added)

Change the Emitter Direction so it goes upward away from the plane

Select the particles and add a Gravity Field

Make it collide with a plane: Make the plane a nCloth - Passive Collider

Select the particles and select: nParticles - Particle Collision Event Editor

In Objects list of the Particle Collision Event Editor: highlight the Particles you want to effect

Set event name: Name it

On which collision do you want the event to happen?

All Collisions - each time it collides it will do it

Collision Number - This only is available when All Collisions is de-selected:
Collision Number 2 means only the second bounce is effected

Event Type:

Emit - ON = the original particle object continues to live after the collision event. The target particle age starts when the new particle object is created. You can indicate that the original particle dies when it collides.

Split - ON = the original particle object dies after the collision event. The target particle inherits its age from the source particle.

Random # Particles
ON = When on, a random number of target particles are created for each collision event. The minimum number of particles is 0 and the maximum number of particles is set by the Num Particles value.
OFF will use Num Particles

Num Particles - Sets the number of target particles created by a single collision event.

Spread - cone angle of area where particles are emitted - pick between 0 + 1, 1=180 degrees

Target Particles - can specify existing particle group or new particle - will pick up the attributes from the specified particles

Inherit Velocity - 0 = no velocity = no bounce; 1 = inherits all velocity = very bouncy
pick a # between 1 + 0 and you will get diminishing bounces as it bounces

Click Create Event

NOTE: You may NOT want the new target particles to Live Forever

Change the Original and Target particles to be differnt types and differnt colors

Changing the Starting Frame

Select the Attribute Editor -> nucleus1 -> Time Attributes -> Enter Start Frame

or keyframe the Emitter Rate to 0 then key it to emit at a later time

or key the magnitude of the field to 0 then key it later to have magnitude