Usage guide for Compositing with Carbon Basic
Follow Filter

The Follow filter takes positional information from a key source and alters positional information in the keyed element.
The Follow filter has three types of channels, Position, Endpoint, and Orientation. These channels derive their information from a key source's edge data, center of the frame ("hot-spot"), center of rotation, edge slope, or frame rotation.

Position channel

The selected key values are used to form an offset to the position of the keyed element. This allows an element to, for example, follow the edge of another element, or remain at a fixed offset from another element, etc.

Endpoint channel

This channel is only used for lines to move the second (end) point. An example would be to use the position channel to move the origin of a line relative to one element, and use the endpoint channel to move the other end of the line relative to a second element. This would result in a line connecting the two elements wherever they might move in the composite.

Orientation channel

This channel does not change the location of the keyed element, but instead causes the element to be rotated by the relative angle between the keyed element and the key source element. An example would be a simulation of the solar system using the orientation channel to keep the Moon facing Earth at all times.

Edge Data

For images the edge data is simply the rectangle used in placing it onto the canvas. For generated shapes it is the list of points used to create the shape. Movement along edge data is proportional to the total linear length of all lines, including curvature, to the elapsed time to total time ratio.

Time modification

Edge following can run backwards by selecting "Retrograde". It can also be advanced in time to start from anywhere along the edge. Time can also be modified to cause more or less than one full trip around the edge using the "loop time" value. This sets the time for one complete trip around the edge. The default value results in one trip.
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