Physics documentation?

[ghost]

It seems like the README doesn't have any definitions of "stiffness" or "damping". I also skimmed through the React Europe talk and didn't see any explanations.

Since this is a "physics-based" library, it would be very helpful to explain what the physics are.

There are a number of issues circling this question:

• https://github.com/chenglou/react-motion/issues/113
• https://github.com/chenglou/react-motion/issues/252
• https://github.com/chenglou/react-motion/issues/60
• https://github.com/chenglou/react-motion/issues/265#issuecomment-184697874

Some desirables:

• [ ] Explain the model: is this a linear (Hooke's law) spring?
• [ ] Explain the algorithm: does this do something like, say, parameterize a step/impulse response function and then sample it to generate the output?

If so, some detailed information like the below image, for example, would be extremely helpful:

[nkbt]

That's really helpful, @talexand! Keen to PR?

[ghost]

I'm keen, but I'll have to sit with the source for a bit. :wink:

[chenglou]

I'm incorporating https://github.com/chenglou/react-motion/issues/265#issuecomment-184697874 soon. Sorry about the codebase; it's trickier than it looks like, partially because it sits at the intersection of React lifecycle, async states, physics and animation coordination with StaggeredMotion and TransitionMotion. The combination of these things makes the code complex; also I partially suck at it =P.

I'd love to have this explained clearly; but we're "competing" against e.g. "it's an animation that slows down and takes 2 seconds" kind of alternative, mainstream animation API here. The more physic theory we put into the docs the more likely people will just go for a CSS ease curve.

That being said, I'd love to have this documented as a dedicated wiki page; it can be very informative and interesting for some people.