Add MathUtils.damp() for framerate independent lerping

[marcofugaro]

Related issue: -

Description

Another useful function is the damp function, which lets you interpolate in a spring-like manner, while being framerate independent.

The implementation comes from this article: Frame rate independent damping using lerp, where basically the author finds a better way of doing lerp(x, y, value * dt).

Unity also has this function nowadays, it's called SmoothDamp, however its implementation is a bit more complex.

[mrdoob]

Thanks!

[makc]

@marcofugaro it is somewhat weird in that in order to supply proper value of lambda users will have to be aware of damp() implementation. and if they are, why not just pass the expression to lerp themselves?

[marcofugaro]

@makc

I think it's just necessary to read the documentation for the user, it says:

lambda - A higher lambda value will make the movement more sudden, and a lower value will make the movement more gradual.

[makc]

I mean if I had, say, 40 fps and lerp(x, y, 0.1), to get similar results when switching to damp(...) I need to solve 0.1 = 1 - exp(-lambda * 25) - and docs just say, Idk try some values?

[makc]

(p s on related note, docs say dt must be in seconds when in fact there is nothing that stops you from using other units like ms)