# When to Use Interpolation in Animations

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Essentially  a track is, a class that modifies a floating point value over time? So when you store the animations, per frame you are storing the change in pos3f, rotatation3f. I am using Collada and Blender, it exports animations in matrix form. So what I would need to do is decompose it into translation and rotation, matrices. Then record the change that those two transformations perform to the basis roation and translation vectors. Then when ever I am doing the animation, instead of multiplying it all through I just read the track information which is simple addition of pos3f tracks and rot3f tracks?

This sounds ingenious. If I understand you correctly, essentially this allows you to side step all the problems of interpolation. So you dont need to use quaternion interpolation or matrix interpolation, all you have to do is linearly interpolate the tracks which are simple floats.

I am understanding what you are saying properly?

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Essentially  a track is, a class that modifies a floating point value over time? So when you store the animations, per frame you are storing the change in pos3f, rotatation3f.

There would be one track for position.x, one for position.y, etc.

I am using Collada and Blender, it exports animations in matrix form.

That is something of a problem as information is lost that way. This caused the incurable bugs I described above.
As one specific example, if you take a linear deogree rotation animation from 0 degrees (let’s say around the Y axis) to 720 degrees, once you convert that to radians and normalize you have a rotation from 0 radians to 0 radians.

I am understanding what you are saying properly?

Yes.
Just get out of matrix form as early as you can, trying to retain as much of the original information as possible.
The bug I mentioned above might not happen if you can sample the animation at regular intervals from within Blender. The begin and end radians might both be 0, but you would interpolate through enough intermediate frames to run through the animation correctly.

L. Spiro

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I dont feel like I am going to grasp it entriely tonight, but at least I now know of tracks and desperately want to learn more, Thank you.
Is there a sitie or a pdf or some book i could read that goes into more detail in the topic of animation tracks. Thank you for your help so much.

Edited by Kastor372

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