TYPE: SOP
TITLE: Point SOP

The Point operation manipulates the position, color, normal, texture
coordinates, and many other attributes of the points in the source. The
attributes can be added, removed, or passed through. It supports two inputs
and inherits the first input by default.

Parameters:
Standard 
    Position            - XYZ position                  /tx /ty /tz
    Weight              - Spline weight of the point    /weight
    Color               - Diffuse color (RGB)           /diffr /diffg /diffb
    Alpha               - Transparency value            /alpha
    Normal              - Normal vector                 /nx /ny /nz
    Texture             - Texture coordinates           /mapu /mapv /mapw
Particle
    Mass                - Point mass                            /mass
    Drag                - Drag coefficient                      /drag
    Tension             - Spring tension for connected edge     /tension
    Spring K            - Spring constant per point             /springk
    Scale               - Particle size multiplier              /pscale
    Velocity            - Velocity vector                       /vx /vy /vz
    Up Vector           - Up vector attribute                   /upx /upy /upz
    Instance            - Geometry to instance on particle
Force
    Radius              - Radius of effect                      /radiusf
    Force Scale         - Multiplier for total force            /scalef
    Radial Force        - Force directed toward attractor       /radialf
    Normal Force        - Directed along normal direction       /normalf
    Edge Force          - Directed along edge direction         /edgef
    Directional Force   - Arbitrary directional force           /dirf
Custom
    Apply Attribute #   - Whether to apply this rule            /apply#
    Name #              - Name of attribute, eg "Cd"            /name#
    Scalar Value        - Value to set scalar attributes        /val#i[1-4]
    String Value        - Value to set string attributes        /sval#

Local Variables
    PT                  - Point number.
    NPT                 - Total number of points.
    CEX, CEY, CEZ       - Centroid of the input geometry.
    TX, TY, TZ          - Point position.
    WEIGHT              - Point spline weight.
    BBX, BBY, BBZ       - Position of point within bounding box, ranges [0-1].
    NX, NY, NZ          - Point normal directions.
    MAPU, MAPV, MAPW    - Point texture coordinates.
    CR, CG, CB          - Diffuse point color.
    CA                  - Point alpha value.
    MASS, DRAG          - Point mass and drag.
    TENSION, SPRINGK    - Spring tension of an edge, and elasticity of a point.
    AGE                 - Number of seconds a particle has been alive
    LIFE                - Particle age divided by life expectancy (0 to 1)
    DIST                - Distance to intersection from the Ray operation.
    VX, VY, VZ          - Point velocity values.
    UPX, UPY, UPZ       - Point up vector values.
    ID                  - Particle ID.
    PSCALE              - Particle Scale
    PT2, NPT2, etc	- Append 2 for the second source.

See also: Vertex(vertex), Primitive(primitive), Transform(xform)
