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I do not understand properly the behavior of the "Interpolation from Curve Mapping" node. At all interpolation nodes the output value of the corresponding Evaluate node is "0" at positon "0" and "1" at position "1". Except for the "Interpolation from Curve Mapping" node; at this node the output value is "-0.5" at positon "0" and "1.5" at position "1", even though the first point of the interpolation curve is at "0,0" and the last is at "1,1". Why behaves the "Interpolation from Curve Mapping" node like this?

Interpolation from Curve Mapping

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  • $\begingroup$ I see unexpected behaviour as well. Not the same as yours. In my experiment I can produce negative values on both ends even though I expect non negative values. $\endgroup$
    – atomicbezierslinger
    Commented May 19, 2016 at 20:43
  • $\begingroup$ May I add a picture to your question which is mentioned above in the comment? $\endgroup$
    – atomicbezierslinger
    Commented May 19, 2016 at 21:06

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This (at the first glimpse) unexpected behavior exists because otherwise you can't create certain types of interpolations. eg the 'back' interpolation with an overshoot would not be possible.

This is why AN (Animation Nodes addon) remaps the Y values: 0.25 -> 0; 0.75 -> 1

All values below 0.25 or above 0.75 will be the 'overshoot' (and you need this overshoot quite often in motion graphics..)

Fortunately, Blender draws the horizontal lines in the curve mapping editor so that it is easy to see where 0.25 and 0.75 are.

Use the Debug Interpolation node to see the mapping performed by Animation Nodes.

enter image description here

If the remapping would not exist, there would just not be enough space in the node ui to have control over the overshoot:

enter image description here

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  • $\begingroup$ Can you give an example of why [you need this overshoot quite often]? $\endgroup$
    – atomicbezierslinger
    Commented May 19, 2016 at 21:08
  • $\begingroup$ It is mainly used for Motion Graphics. eg when you want to animate an object that flys into the scene it looks much better if it goes over that target and comes back afterwards. $\endgroup$
    – Jacques Lucke
    Commented May 19, 2016 at 21:10
  • $\begingroup$ Your answer is unclear. What is "that" which you implemented at first and what is "it" to which you reverted? What is "that" for which there is a reason (2nd sentence)? And what is "AN?" Please make this a complete answer. $\endgroup$
    – Matt
    Commented May 19, 2016 at 21:12
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    $\begingroup$ That's right, you have to know how it has to be configured. But the zoom-variant also has some advantages: 1. No astonishment at the mapping of the values (the output value at x corresponds to the adjusted y value). 2. No restriction of the curve point values (now the values are (visually) limited to 0,-0.5;1,1.5) 3. No mapping to remapping, when you create the curve (as in my case) from a specified list of x-y-values. Perhaps it would be the easiest solution to show a tutorial in the documentation how to zoom out. Many thanks for answering my questions. $\endgroup$
    – George Miller
    Commented May 20, 2016 at 16:36
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    $\begingroup$ That convinced me. The next version will contain the new behavior. thanks :) $\endgroup$
    – Jacques Lucke
    Commented May 21, 2016 at 13:02

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