Particle System
Detailed Description
This section of the documentation covers Nebula particle system.Nebula particle system is consist of particle server, particle emitter and particle shape node.
- nParticleServer - A class for particle server which is responsible for creating and managing of particle emitters.
- nParticleEmitter - A class for particle emitter which generates particles.
- nParticleShapeNode - A class for particle scene node which is used for rendering a created particle emitter.
You might want to create a nParticleShapeNode to render particles in a scene. When a rendering context of a nParticleShapeNode is created(done by calling nParticleShapeNode::RenderContextCreated() function), a new particle emitter is create from nParticleServer and the node saves emitter key to its render context for its later access. Whenever the node is rendered, it renders emitted particles by calling its emitter's trigger function(nParticleEmitter::Trigger()) and rendering fuction (nParticleEmitter::Render()).
Besides above classes, there is nParticle class which represents each particle itself.
The particle system in Nebula2 is quite different to the one in Nebula1. It makes heavy use of a new class nEnvelopeCurve to control the particle attributes. See the next sections for what envelope curvers and attibute are.
Envelope Curves
Most of the particle attributes are set using envelope curves, these take a position in the range [0.0, 1.0] and return a value based on the shape of the curve. The curve is defined by 8 float arguments:
- Key Frame 0 - 3: These are the values of the key frames
- Key Frame Position 1 - 2: These control the position of the second and third key frames. The first and last key frames are at 0.0 and 1.0.
- Frequency: The curve can be altered by an optional cosine/sine wave. This is the frequency of that sine wave. 1.0 would be one cycle over the curve, 2.0 would be two cycles over the curve, etc.
- Amplitude: This is the amplitude of the wave. The wave value is added to the curve but remember that the wave value will be negative for half of a cycle.
- Modulation Func: This sets the wave to be sine or cosine. 0 is sine and 1 is cosine.
It seems complicated at first but if you play with it soon makes sense.
Attribute
The attributes are split into two groups according to how their envelopes are keyed.This first group of attributes change over the course of the particles emission duration as set by the script command .setemissionduration. This means that the position on the curve will be 0.0 at the start of the emission and 1.0 at the end of the emission time. They will loop if loop is set to true.
- Note:
- The particle life time should never be less than 0.0, be careful when using waves to make sure that the amplitude is always >= to the lowest key frame value.
.setemissionfrequency
.setparticlelifetime
.setparticlestartvelocity
The second group of attributes are all based on each particle's age. When a particle is born the position on the curve will be 0.0 and 1.0 when it dies.
.setparticlescale
.setparticlealpha
.setparticlergb
.setparticlerotationvelocity
.setparticleweight
.setparticlesidevelocity1
.setparticlesidevelocity2
.setparticleairresistance
.setparticlevelocityfactor
Classes | |
| class | nParticle |
| This class represents a single particle in a particle system. More... | |
| class | nParticle2Emitter |
| class | nParticleEmitter |
| class | nParticleServer |
| Particle subsystem server. Holds an array of all particles and all particle emitters in the world. Take care when updating them, the rendering is a function of the emitters. More... | |
