Lesson 1: Creating an nParticle system

In the first step you create an nParticle object and its emitter object. An emitter controls the position, direction, quantity and initial velocity of the emitted nParticles when they are born (emitted into the scene).

Lesson setup

To ensure the lesson works as described, do these steps before beginning:

Open the scene file named Smoke_Simulation_1.mb.
This file can be found in the GettingStarted directory that you set as your Maya project:
```
GettingStarted/nParticles/Smoke_Simulation_1.mb
```
This scene includes textured models that have been created for you. The desk, ashtray, and cigarette provided are all polygon meshes.

Creating an nParticle and emitter object

To create an nParticle and emitter objects

Select nParticles > Create nParticles, and select Cloud.

Selecting Cloud presets some nParticleShape attributes that are suitable for simulation such as smoke, dust, or fog.
To create an nParticle emitter object, select nParticles > Create nParticles > Create Emitter > .
The Emitter Options (Create) window appears.
In the Emitter Options (Create) window, select Edit > Reset Settings.
In the Emitter name field, type Emitter_Smoke.
Naming your emitter object makes it easier to identify in the Outliner when you want to select it and make attribute adjustments.
From the Solver list, select Create New Solver.
Selecting a solver determines which Maya Nucleus system your nParticles belong to.
From the Emitter type list, select Volume.
Volume emitters are well suited when you are trying to evenly emit particles from a specific area, such from the tip the cigarette, as opposed to a single point in space.
Set Rate (particle/sec) to 100.
This sets the number of particles that are emitted into the scene. This directly impacts the particle density in the scene. The higher the emission rate the thicker the smoke appears in your scene.
In the Distance/Direction Attributes section, do the following:
- Set DirectionX to 0.
- Set DirectionY to 1.
Direction sets the emission direction relative to the emitter’s position and orientation. When DirectionY is set to 1, the nParticle are emitted along the Y axis to emulate the smoke rising in the air.
In the Basic Emission Speed Attributes section, set Speed random to 5. When Speed random is set to a positive value, the emitter generates random speeds for each nParticle.
In the Volume Emitter Attributes, do the following:
- From the Volume shape list, select Sphere.
- Set Volume sweep to 180.
  This creates an emitter in the shape of a half sphere, which covers the tip of the cigarette.
In the Volume Speed Attributes section, do the following:
- Set Along axis to 1.
- Set Random direction to 0.1.
  This creates some directional noise in the emitted nParticles and causes them to form a cone-shape particle cloud.
- Set Directional speed to 10.
  This setting adds speed in the direction specified by the Direction XYZ attributes of all volume emitters.
Click Create.
An Emitter_Smoke1, nParticleShape1, and a nucleus1 node appear in the Attribute Editor.

nParticle and Nucleus nodes

When you create a new nParticle object, a new Nucleus system is created. As part of a Nucleus system, the nParticles can interact with other Nucleus objects that are assigned to the Nucleus solver. If you created an emitter for your nParticles, an emitter node is also created. The following sections describe the new nodes in your new Nucleus system.

nParticleShape1 is the node that carries all the nParticle object attributes that define the appearance, size, and overall behavior of each particle in the nParticle system.

Emitter_Smoker1 is the nParticle emitter node, which carries all the particle emission attributes such as particle emission rate and emitter type. This node also carries the transformation attributes (translation, rotation, scale) for the emitter object. The emitter node used by nParticles is the same emitter node used by Maya classic particles.

nucleus1 is the Maya Nucleus solver node, which carries all the attributes affecting the solver system, including internal forces. For more information, see Maya Nucleus solver properties.

Beyond the lesson

In this lesson you were introduced to the basic concepts of nParticles and the Nucleus dynamics system. In addition, you learned how to:

Create nParticles from a source object called an emitter.
When you create an nParticle object and emitter, a Nucleus node is also created.
Use a volume emitter with an nParticle system.
Set up the general behavior of your nParticles by adjusting volume emitter attributes such as Distance/Direction and Volume Speed Attributes.

For more information and related techniques about nParticles, refer to the Maya Help.