"smooth_damp" functions for primitives and math structs

[vveisard]

What problem does this solve or what need does it fill?

I need to smoothly move a value towards a target value over time using velocity and other parameters (see below).

What solution would you like?

I would like a set of "smooth_damp" functions for primitives and which have:

• current
• target
• velocity
• smooth time
• max value delta
• time delta

Importantly, I would also like a spherical smooth_damp for Vec2 and Vec3.

What alternative(s) have you considered?

A similar effect can be achieved using interpolation functions while updating the start value. However, this lacks all the parameters of a smooth_damp function.

Additional context

https://docs.unity3d.com/ScriptReference/Vector3.SmoothDamp.html

[alice-i-cecile]

I definitely want this: very useful!

This feels like something that could be added as an auto-implemented method on the Animatable trait. Does that make sense to you?

You would probably need to special case the spherical interpolation in some form. Perhaps a newtyped Vec2/Vec3 that captures the notion of operating in spherical coordinates?

[IQuick143]

Perhaps a newtyped Vec2/Vec3 that captures the notion of operating in spherical coordinates?
How about a Dir2/3, it's already a newtyped Vec2/3, bound to the unit sphere.

[alice-i-cecile]

Dir2 and Dir3 are a great primitive for this, and interpolating them should definitely be on the surface of the n-sphere. I think that's probably enough actually, as long as we have an example that shows how to use those interpolation methods to create a spherical path around a center between two points.

[SIGSTACKFAULT]

If Dir3 gets it then Quat should too

[vveisard]

This feels like something that could be added as an auto-implemented method on the Animatable trait. Does that make sense to you?

Yes, Animatable seems like the right place for a smooth_damp method. However, I would expect a smooth_damp method for f32, Rotation2d, Vec2, Vec3, Dir2, Dir3, and Quat, and some of those lack an Animatable implementation.

I'm not familiar enough with Rust to know if auto-implement is the right thing to do.

[alice-i-cecile]

Pretty much all of those should have an Animatable implementation :) But yes, this can just be a method on the trait with a default implementation of the method.