====== Spline Motion (Motion Plugin) ======

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This node can evaluate [[primitive]] and return the position as well as the orientation at any position along the spline.

===== Controls =====

==== Spline ====

Allows you to pick any of the [[primitive]] in the scene to evaluate.

==== Displacement ====

This is the position on the spline. Depending on the **Displacement Type**, 0-100% is either the complete length of a spline or the first span. 100%-200% would then be the second span respectively.

==== Displacement Type ====

This determines how the **Displacement** is interpreted to evaluate the spline.

  * **Complete Spline** In this mode, the spline is taken as a whole, 0% is the start of the spline, 50% the middle of it and 100% the end.
  * **Per Span** In this mode, every successive value of 100% corresponds to a span. For example, an open spline has five knots - which is four spans. 400% would then be the and of the spline. 250% would evaluate half way between the third and the fourth knot.

==== Look Ahead ====

If Look Ahead is off, the rotation will align to the spline at the current position.

If Look Ahead is turned on, the rotation will be align to a different position on the spline, depending on the value of **Look Ahead Displacement**.

==== Look Ahead Displacement====

If **Look Ahead** is enabled, this determines how far ahead (or back) along the spline the point is that the rotation aligns to. This is using the same units as **Displacement** and also depends on **Displacement Type**.

This value is added to the current position.

==== World Coordinates ====

Computes the point on the spline and the orientation in world as opposed to object coordinates.
==== Pre/Post Behaviour ====

Determines what happens if the displacement would evaluate before the start or beyond the end of the spline respectively.

These options are only available for open splines:

  * **Hold** Holds the position at the start or the end of the spline respectively.
  * **Loop** Loops the position on the spline.
  * **Mirror** Mirrors the position on the spline.

==== X/Y/Z Mode ====

The positions computed by the node may be modified here.
The input position is whatever the motion stack provides up to the plugin, usually the keyframed position.

  * **Replace** (default) The position value of the axis is overwritten with the value computed by the node.
  * **Ignore** The computed position on the spline is ignored and the original value passes through.
  * **Add** The computed value on the spline is added to the position. 
  * **Multiply** The computed value on the spline is multiplied by the position.

==== Heading/Pitch/Bank Mode ====

The rotation computed by the node may be modified here.
The input rotation is whatever the motion stack provides up to the plugin, usually the keyframed rotation.

  * **Replace** (default) The rotation value of the axis is overwritten with the value computed by the node.
  * **Ignore** The computed rotation on the spline is ignored and the original value passes through.
  * **Add** The computed value on the spline is added to the rotation.