Two animations with identical keyframe values can feel completely different because of curve shape. The Spline Editor is where linear motion becomes designed motion.
Read the curve
The horizontal axis is time and the vertical axis is parameter value. A steep section means rapid change; a flat section means slow change or a hold.
Linear, Smooth and Step
Linear creates constant interpolation between keys. Smooth uses tangents for acceleration/deceleration. Step does not interpolate intermediate values and is useful for switches or hard state changes.
Shape easing with tangents
There is no universal “good S-curve.” A light UI element, a heavy logo and a camera move need different acceleration. Adjust tangents and judge the animation, not the curve shape in isolation.
Overshoot and settle
For a controlled overshoot, let the value pass the target slightly and return. Small amounts—often only a few percent—usually feel more intentional than a large bounce.
Loop, PingPong and Relative
Repeat behaviors turn a short animation into a cycle. Loop repeats, PingPong reverses direction, and Relative can continue changing across repetitions. Always inspect the seam between the last and first frame.
TimeStretch and duration changes
When an existing animation is too long or short, retime the block instead of moving dozens of keys manually. After stretching, check the speed through the middle of the motion again.
Key takeaway
The Spline Editor controls motion character and speed. A curve is successful when the animation feels right in the Viewer—not when the graph simply looks elegant.