For information on where particle elements are in the explorer and other ways of finding particle elements in a scene, see Finding Particle-based System Elements.
The Particle simulator makes it easy to animate all types of phenomena that can be based on particles, such as dry ice flowing out of a flask in an alchemist’s laboratory, fireworks bursting in the night sky, or snowflakes falling gently on a gray winter’s day.
Particles are affected by elements of the scene’s environment, such as lighting and objects. As a result, you can create shadows for them, create accurate obstacle collisions using the actual objects, and even deform particle streams the same way you deform geometry. When it comes to previewing the effects, you can simply create a render region to immediately see the results.
Particles themselves are actually points, meaning that you can tag them like points, delete them like points, create clusters of them, deform them like clusters, and constrain objects to clusters of them.
What Makes Up a Particle System?
A particle system is an assembly of different parts that work together: the particle simulator, the cloud, the emitter, the particle type, and the shader. Natural forces and obstacle objects also affect the particle simulation, but are not directly part of the particle system’s structure.
|
For information on where particle elements are in the explorer and other ways of finding particle elements in a scene, see Finding Particle-based System Elements. |
• The particle simulator is the operator that generates the particles, represented by the particle cloud, as well as controls how the particles evolve and are affected by forces, obstacles, and events. The particle cloud is like the “root” for all the particle system pieces. It is actually a geometry (a “cloud” of points) that results from the particle simulator doing its thing. You can have multiple particle clouds in a scene.
• The emitter is associated to a particle cloud, and is a combination of two things:
- The object from which the particles are emitted.
and
- The set of properties defining how the particles are emitted, such as their rate (density), speed, and spread angle. You can have multiple emitters per cloud.
• One or more particle types is associated with each emitter but are actually associated with each particle cloud. Particles types are like the “recipes” or templates that describe what each group of particles looks like (mass, size, shape, color, etc.). You can have an unlimited number of particle types in a scene and apply them to any emitter object, one at a time.
When you create a particle simulation, the particle simulator generates clusters to identify which particles belong of which particle type.
• The particle shaders define the rendered look of the particles, letting you define the basic shape of the particles and set color, shadows, color burn etc. There are several special shaders created for particle systems, but you can also connect standard shaders in the particle’s render tree. You can apply particle shaders to a either cloud or to individual particle types of a cloud.
Particle event scripts (scripted events) replace and expand upon pre-collision scripts that were available in previous versions of Softimage. Whatever modifications you create in a scripted event are evaluated and “reinjected” into the simulation at every frame so that the next simulation step takes them into consideration. If you have a pre-collision script from a previous version, you can replace it with a particle event that is triggered at every frame with a scripted action.
For more information on particle events in general, see Creating a Particle Event; for scripted events, see Scripting a Particle Event.
You can use scripted operators with particles, but there is a limitation with them. Scripted operators modify the particles for the evaluated frame but the results are not used for the next evaluation of the simulation feedback loop. However, you can use scripted operators to create your own custom simulation or mimic flocking.
Basically, if you want to modify the velocity, position, or mass of the particles to affect the simulation, you should use a scripted event. If you’re just modifying non-dynamic attributes like the particle’s size or color, you can use scripted operators.
For more information on scripted operators, see Scripted Operators [ Customization ].
When you’re scripting particles, you can use the information found in the SDK documentation. To access this documentation, you can open the script editor and press F1 or choose Help > SDK Guide from the main menu in Softimage.
The particle objects used can all be found under the Object link (the Object Model) in the Scripting Reference. These are the objects for particles: Particle, ParticleAttribute, Particle AttributeCollection, ParticleCloud, ParticleCloudPrimitive, ParticleCollection, ParticleType, and ParticleTypeCollection.
As well, see the SDK Customization Guide and the Working with Softimage for Developers sections for more information about particles. These guides are also available in the Scripting Reference contents.
Autodesk Softimage v.7.5