TYPE: SOP
TITLE: Particle SOP

The Particle operation creates and controls motion of particles for particle
system simulations.

Parameters:
State
    Behavior             - Type of operation to perform.
    Point Reuse          - How to reuse the points from the input geometry.
                           The first two options behave differently only
                           when modifying source geometry.
    StartTime            - Time at which the simulation resets.     /timestart
    Preroll Time         - At start time, simulation has already been
                           running this long.        		/timepreroll
    Time Inc             - Time increment to use for each step of the
                           particle simulation.  Decrease to get
                           sub-frame cooking.                       /timeinc
    Jitter Births        - Jitters pixels of particles at birth.
    Accurate Moves       - Particles move more accurately.
    Remove Unused points - Removes unused points from input geometry.
    Attractor Use                 - How the attractor points affect particles
        All points                - All points affect each particle
        Single point per particle - Only one point affects each particle
Forces
    External Force  - Force of gravity on particles.              /external[xyz]
    Wind            - Wind force acting on particles.      /windx /windy /windz
    Turbulence      - Amplitude of turbulence along axes.  /turbx /turby /turbz
    Turb Period     - Inverse variance of turbulence in space.       /period
    Seed            - Seed for random turbulence generator.          /seed
Particles
    Add Particle ID    - Each particle receives a unique ID number.
    Add Mass Attribute - Causes particle mass to be calculated.
    Mass               - Relative mass of each particle.             /mass
    Add Drag Attribute - Causes drag coefficient to be calculated.
    Drag               - Drag of each particle.                      /drag
    Birth              - Number of particles "born" each second.     /birth
    Life Expect        - How long each particle exists, in seconds.  /life
    Life Variance      - Variance of the life expectancy in seconds. /lifevar
Limits
    + Limit Plane, -~sLimit Plane - Particles die or bounce off limit 
			 planes on contact.
		         /limitposx /... /limitposz, /limitnegx /... /limitnegz
    Hit Behavior      - Whether particles die or bounce on limit planes.
    Gain Tangent      - Energy loss tangent to the collision.        /gaintan
    Gain Normal       - Energy loss perpendicular to the collision.  /gainnorm
    Split             - Whether the particle splits upon collision or death.
    Min/max splits    - Number of particles a particle splits into.  /splitmin 
								     /splitmax
    Split Velocity    - Base velocity for split particles.           /splitvelx 
							  /splitvely /splitvelz
    Velocity Variance - Random amount added to split velocity.       /splitvarx
							  /splitvary /splitvarz
Render tab
    Particle Type  - How the particle is rendered.
    Particle Size  - How large particles are.                        /prsize
    Particle Blur  - Length of particle when rendered.               /prblur
    Sphere Normals - When rendering as disks, fake normals to appear spherical.

See also: Pop Merge(pop), POP Network(popnet)
