Interpolation and easing
Take a close look at the X Location and Y Euler Rotation F-curves and note what happens to the segment between the keyframes on frames 10 and 90. The line gently begins to rise, reaches its steepest point at frame 50 as it continues to rise, then gently rolls off at the top.
Each keyframe dictates that a certain property equals a certain value at a certain time. When that keyframe is followed by another keyframe of a different value, the property’s value must change from one to the other as the animation plays forward through time. On all the frames in between, we can think of the property itself as “moving” from one value to the next.
The way by which one value transitions to another is called interpolation. It was mentioned briefly in the previous chapter; it’s the reason we can make just two keyframes on two different frames and get smooth-looking motion along all the frames in between. Whereas animation techniques such...
