TYPE: POP
TITLE: Orbit POP

The Orbit POP applies forces to the particles such that they orbit 
about a center. To help visualize the effect of this operator, 
turn on the template flag to view the acceleration guides.

This POP modifies the following attributes: accel.

Parameters:
    Activation                  - Turns the POP on and off	/activate
    Source Group                - Subset of points which will orbit
Orbit
    Override Axis               - Override for the orbit axis attribute
    Axis                        - Normal to the orbit plane	
							/axisx /axisy /aaxisz
    Override Radius             - Override for the orbit radius attribute
    Radius                      - Radius of orbit in units	/radius
    Override Speed              - Override for the orbit speed attribute
    Speed                       - Speed of the orbit in RPM	/speed
    Scale                       - Scaling factor that controls how fast 
                                  particles move into their proper orbit
								/scale
Center
    Center Group                - Subset of points to act as centers
    Center Type                 - Specifies what is used as the center
	Particle Spatial Center - The center of the box bounding the center 
                                  particles.
        Particle Center of Mass - The center of mass of the center particles.
        Particle Density Center - Corresponds to the center of mass with all
                                  particles having equal mass.
        Center Point            - Center Point co-ordinates as specified.
        Individual Particles    - Each orbiting particle is assigned one
                                  center particle to orbit around.
    Override Center Point       - Override for the orbit center attribute
    Center Point                - point to orbit around	
						/cntrlocx /cntrlocy /cntrlocz
    Orbit Index                 - How to interpret the orbit index

Local Variables
    Overview - The standard local variables are usable in this POP.  Please
               refer to the Houdini manual for more details.
