Interp Mode

The FcrvEdit->Interp Mode commands in the Motion module let you choose the type of interpolation for the function curve. Interpolation is how animation is defined between key points on a function curve. This affects the acceleration and deceleration of the animation, and many other factors.

Procedure

1. Select an animated object.
2. Select a function curve using the FcrvSelect menu cell command. The Function Curve window appears.
3. Select a function curve in the window.
4. Choose the FcrvEdit->Interp Mode command for the type of interpolation you want to create:
   Constant, Linear, Spline, Slope 0, or Plateau.

Constant

The FcrvEdit->Constant command controls the interpolation between key points on a function curve by repeating the value of a keyframe for each frame after it. The movement is characterized by sudden changes and then static positions.

You can also set this type of interpolation by selecting the CON option from the Fcurve window title bar.

Linear

The FcrvEdit->Linear command creates a regular interpolation between key points making the function curve appear as a straight line. The movement is characterized by sudden changes in movement at each key point.

You can also set this type of interpolation by selecting the LIN option from the Fcurve window title bar.

Spline

The FcrvEdit->Spline command uses a spline interpolation between key points with an acceleration and a deceleration, depending on the slopes at the key points. This is the default interpolation type.

This results in a smooth transition of motion at key points. You can control acceleration and deceleration with the FcrvEdit->Edit Key Point and FcrvEdit->Slope Management commands.

You can also set this type of interpolation by selecting the SPL option from the Fcurve window title bar.

Slope 0

The FcrvEdit->Slope 0 command creates a spline interpolation, but allows you to constrain some or all key points of a function curve to a slope of 0. The tangent handles of the key points all remain horizontal (that is, with a slope of 0).

You can also set this type of interpolation by selecting the SL0 option from the Fcurve window title bar.

Note:

The Slope 0 type of interpolation only works with automatically created slopes. If you edit the slope manually, your edits override these settings.

Plateau

The FcrvEdit->Plateau command automatically sets the slope of a key point to 0 if the next key point has the same value, or if that key point is a local minimum or maximum. A local minimum/maximum is a key point where both previous and next key points have either smaller (in the case of maxima) or larger (in the case of minima) values.

This is very useful for automatically preventing function curves from going above or below key points (thus exceeding a pause value) instead of having to edit the slopes manually.

The Plateau command is commonly used to pause a motion. Two key points with the same value are interpolated, so they both have horizontal slopes like this:

You can also set this type of interpolation by selecting the PLA option from the Fcurve window title bar.

Note:

The Plateau type of interpolation only works with automatically created slopes. If you edit the slope handles manually, your edits override these settings.

Last updated 02-apr-1998