TYPE: COP
TITLE: Geokey COP

This operation keys out parts of the image based on point position, normal
direction or both. A point plane and/or a normal are needed to perform this
operation. 

Geokey can simulate lighting from point lights and infinite sources by 
generating masks that can be used by color correction COPs, like Bright.

Middle click on the dialog '?' help for more help on maskable operations.
Right click on the dialog '?' help for more help on VEX operations. 

Parameters:
Geokey
    Key Operation - ~s
	Distance from Point - All pixels within a certain distance of a
			      specified point are keyed (Point plane required).
	Normal Direction    - All pixels with normals pointing in the
			      same direction as the specified normal
			      are keyed (Normal plane required).
	Angle from Point    - All pixels with normals pointing at the
			      specified point are keyed (Point and
			      normal planes required).
	Distance & Angle    - All pixels with normals pointing at the 
	    From Point        specified point, within a certain distance
			      are keyed (Point and Normal planes required).
	Clip Plane          - All pixels on one side of the clip plane
			      are keyed (Point plane required).
    Point Origin     - A point to key from.
    Point Distance   - The distance from the point at which to stop keying.
    Distance Dropoff - The size of the dropoff region after the distance
		       radius.
    Normal Direction - The normal direction to key from.
    Normal Deviation - The amount of degrees that a normal can deviate
		       from the specified normal before being rejected.
    Normal Dropoff   - The amount of degrees of dropoff after the normal
		       deviation.
    Clipping Plane   - The orientation of the clip plane.
    Clip Plane Normal - The normal of the user-defined clip plane.
    Clip Plane Origin - Translates the clip plane. 
    Rolloff          - The rolloff function for the dropoff regions.
    Supersample      - The number of subpixels sampled per pixel in one
		       direction (2 samples 4 pixels, 3 samples 9). More
		       subsamples produce finer edges, at the cost of
		       performance.
    Discard Keyed Region - If on, the keyed region is discarded.

Mask & Plane Scope, Frame Scope
    Overview - See extra help (Middle click on the dialog '?' help).

Local Variables:
    L   - Sequence length
    S   - Start of sequence
    E   - End of sequence
    IL  - Input sequence length
    SR  - Sequence frame rate
    NP  - Number of planes in sequence
    W,H - Width and height of image
    I   - Image index (0 at start frame)
    IT  - Image time (0 at start frame)
    AI  - Current plane array index
    PI  - Current plane index
    PC  - Num of channels in current plane
