Paint Effects
syllabus | schedule | projects | class notes | resources | students | Digital Arts website
Rigid Bodies


Works with the Nucleus solver which is the same used for nCloth. It can collide and interact with other nParticle objects and nCloth if they are assigned to the same Nucleus solver. nConstraints are used with nParticles.

Differences between nParticles and Particles:

Fill object, Self colliding (particles colliding with other particles, built in Nucleus wind and gravity, nConstraints, liquid simulations, converting particles to polygon meshes, force fields to attract or repel other particles or nCloth, nCache to save the simulation data.

To create nParticles:

nParticles Create

Preset types of particles have attributes set already but you can change them later.

Thick Clouds

Four methods of creating nParticles:

  • Use the nParticle Tool
  • Create an nParticle emitter
  • Emit nParticles from an object
  • Fill an object with nParticles

Fill an object is new to nParticles. You must have a polygon mesh to fill first.

You must first convert the polygon object to a Passive Collision Object:

Select the object then - nMesh > Create Passive Collider

To fill the object: nParticles - Select the mesh and Create nParticles - Fill Object Obtions

Fill Object

The option window lets you define parameters of the fill.

fill options

Solver - can have a different solver for each simulation

Resolution - the number of particlesand size of the particles to fill the object - small number = less& big particles

Fill Bounds Min X, Max X, Y, Z - setshow close to the edge of the object they fill it

Particle Density - size of nParticles and how loosely or tightly packed they are

Close Packing - ON = particles are packed like a honeycomb - OFF = packed in even rows

Double Walled - ON = only used with double walled geometry

Particle Fill - fills it up with the particles


Each simulation solver should only contain the elements that interact with each other.

To select which solver to assign the elements to:

1. Select the nParticles

2. nDynamics menu set - nSolver - Assign Solver

3. From the solver list select the solver you want

To create a new solver:

1. After selecting Assign Solver you can choose New Solver from the solver list

nParticles vs Particles

1. There are a number of presets associated with the particle types.

2. Uses a different (better) algorithm to solve the math in the simulation.

3. nParticles can be created in the same way as regular particles but the Attribute Editor will be different. In many ways it is much more intuitive in how you change parameters.

nParticle Attribribute Editor

Some nParticle attributes act the same as Particles:

• lifespan
• Per Particle (Array)
      BUT it has already added Radius, Opacity, Color and Incandescence attributes so you don't need to
• create and edit goals -
      But you may need to turn ON - in Dynamic Properties: Ignore Solver Wind and Ignore Solver Gravity
• Instancing Geometry
• Particle Collision Event Editor
• Connecting Fields, Emitters, and Collision objects
• Duplicating Particles
* Assigning image sequences to sprites

Some nParticle attributes are different from Particles:

Particle Size

nParticle Size

nParticles uses a number of ramps to control attributes.

Understanding the scale ramp:

The ramp is associated with the lifespan of the particle when Radius Scale Input is set to Age - this means when they are born and when they die is important. The Lifespan attribute is referenced to find out how long they will live.

You can set different values at various points in their life by clicking on the ramp and moving the points up or down or back and forth.

Vertical = scale and horizontal = age.

This can also be set using the Selected Position and Selected Value

Interpolation - how the particle size blends between each position on the ramp.

Set Radius Scale Input - which attribute is used as the input attribute for the Radius Scale ramp.

Input Max - define the range of the Radius Scale ramp.

Radius Scale Randomize - to randomize the per-particle Radius


nParticle Collisions

nParticles can collide with them self (self-colliding), other nParticles, nCloth or passive objects that are assigned to the same Nucleus solver.

1. Create nParticles and select them

2. In Attribute Editor - Collisions:

• Turn OFF or ON the Collide

• Turn OFF or ON the Self Collide

Collide Strength - 1 = full strength, 0= collisions OFF, inbetween numbers effects the way they bounce off each other

Collision Layers - you can set the collisions to a specific layer so it won't collide with things you do not want it to collide with

Collide Width Scale - increases the thickness of the collision volume

Self Collide Width Scale - increases the thickness of the collision volume

Bounce - adjust the rebound

Friction - adjust the resistance to the bounce

Stickiness - adjust the tendency to stik to other Nucleus objects (nParticles, nCoth)

Dynamic Properties

Dynamic Attributes

Behavior in relationship to Nucleus forces

Forces in World - ON or OFF = ignore all forces

Ignore Solver Wind or Gravity - there is a built in Nucleus Wind and Gravity and it is attached to the nParticles by default

Local Force - like gravity - set the X Y Z
Local Wind - XYZ
Dynamic Weight - how effected they will be
Conserve - how it maintains it current motion (or not)
Drag - force opposed to the motion
Damp - a restraint to the motion
Mass - set for all (to change over time or based on other attributes use the ramp)

Mass Scale Ramp

This acts the same as the Particle Size ramp but note that the Mass Scale Input is not receiving input from any other source. If you set Mass Scale Input to Radius for example then the big particles will have greater mass and the smaller ones less.

Force Field Generation

Force Field

Seelect the nParticle that you want to emit the force field

Turn it on by selecting one of the following:

ThicknessRelative: Generates a Point Force Field that is relative to the radius of the nParticle object.

World Space:
Generates a Point Force Field that is relative to world space.

Adjust Point Field Magnitude

Adjust Point Field Distance

Point Field Scale

Having attributes effect the amount of magnitude

Point Field Dropoff

You can use the Point Field Dropoff ramp to specify how much the Point Field Magnitude drops off