User Manual

 Region: The Region tab lets you choose what kind of geometric region is used to
disperse particles into space and whether you’re emitting particles from the region’s
volume or surface. The Winding Rule and Winding Ray Direction controls determine
how the mesh region will handle particle creation with geometric meshes that are not
completely closed, as is common in many meshes imported from external applications.
Tweaking these last parameters is common when using imported mesh geometry as a
region for emitting particles, since even geometry that appears closed will frequently
appear to “leak” particles thanks to improperly welded vertices.
Forces
Many of the particle nodes found in the Particles bin of the Effects Library are “forces” that
enhance a particle simulation by simulating the effect of various forces acting upon the particles
generated by an emitter.
Some forces, including pDirectionalForce, pFlock, pFriction, pTurbulence, and pVortex, are rules
that act upon particles without the need for any other input. These are simply “acts of nature”
that cause particles to behave in different ways.
Other forces, such as pAvoid, pBounce, pFollow, and pKill, work in conjunction with 3D
geometry in a scene such as shapes or planes to cause things to happen when a particle
interacts or comes near that geometry. Note that some of the particles described previously
can also use geometry to direct their actions, so these two categories of forces are not always
that clear-cut.
Compositing
The pMerge node is a simple way to combine multiple emitters so that different types of
particles work together to create a sophisticated result. The pMerge node has no parameters;
you simply connect emitters to it, and they’re automatically combined.
Rendering
The pRender node is required whether you’re connecting a particle system’s output to a 2D
Merge node or to a Merge3D node for integration into a 3D scene. Along with the pEmitter
node, this is the only other node that’s absolutely required to create a particle system.
 Controls: The main controls that let you choose whether to output 2D or 3D image
data, and whether to add blur or glow effects to the particle systems, along with a host
of other details controlling how particles will be rendered.
 Scene: These controls let you transform the overall particle scene all at once.
 Grid: The grid is a helpful, non-rendering guide used to orient 2D particles in 3D space.
The grid is never output in renders. The width, depth, number of lines, and grid color
can be set using the controls found in this tab.
 Image: Controls the output of the pRender node, with controls over the process mode,
resolution, and color space settings of the output.
Chapter – 78 Particle Systems 1613