In 1988 Andrew Witkin and Michael Kass, at Schlumberger Palo Alto Research, gave a desk lamp a body and told it what to do and how: "jump from here to there", "don't waste energy". A search then found the motion that obeys Newton's laws and spends the least muscle. Nothing in the problem names a crouch, yet the lamp crouched before it jumped: "Luxo assumes a crouch providing a pose from which to build momentum." Why? Any creature "can only accelerate its own center of mass by pushing on something else," and "while airborne there is nothing to push on." So it squashes, stretches against the floor, and folds to land: "These elements emerge out of physical necessity, rather than being explicitly keyframed." Two years earlier John Lasseter keyed Luxo Jr.'s hop by hand, from two keys, "the first where the hop starts and the second where he lands", and then "Keyframes were set for just about every frame." Witkin and Kass still wrote that personality and appeal "will surely be left to the animator's artistry and skill for a long time to come."

Our lamp, its jump and every pass of the search are our own 2D solve, not film footage or the paper's figures.

What would you never let a computer animate for you?

Sources: Andrew Witkin and Michael Kass, "Spacetime Constraints", SIGGRAPH 1988 (Computer Graphics 22(4)), and their SIGGRAPH 1988 video notes; John Lasseter, "Principles of Traditional Animation Applied to 3D Computer Animation", SIGGRAPH 1987 (Pixar).
Sounds: our own, made in code (earshot, CC0).