Extrapolation
In addition to setting interpolation for areas between keyframes, you can define how
Motion generates the values before the first keyframe and after the last one. This is known
as extrapolation. When you set a such a method for a parameter, keyframes are added
beyond your original keyframes, which is useful to extend the duration of an effect such
as a moving background. Several extrapolation methods are available Before First Keyframe
and After First Keyframe submenus in the Animation menu: Constant, Linear, Ping-Pong,
Repeat, and Progressive.
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To apply an extrapolation method to a parameter before the first keyframe
µ
Click in the fifth column of the parameter list in the Keyframe Editor to open the Animation
menu for the parameter to change, then choose an item from the Before First Keyframe
submenu.
To apply an extrapolation method to a parameter after the last keyframe
µ
Click in the fifth column of the parameter list in the Keyframe Editor to open the Animation
shortcut menu for the parameter to change, then choose an item from After Last Keyframe
submenu.
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The following extrapolation options are available in the Before First Keyframe and After
Last Keyframe submenus:
• Constant: This method, the default, holds the beginning or ending segments of the
curve to the same value as the first or last keyframe.
• Linear: This method extends the curve beyond the first or last keyframes uniformly,
along the existing trajectory of the first or last keyframe.
• Ping Pong: This method copies the curve and repeats it, alternating forward and
backward.
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• Repeat: This method duplicates the curve, applying it again and again.
• Progressive: This method extends the curve by repeating the existing shape of the
curve, but rather than returning to the exact values, repeats from the existing end value.
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