Vector3 "rotate towards another Vector3" function

[ghost]

It would be nice to have a Vector3 function that rotates it towards another Vector3, restricted to a maximum rotation delta. This exists in Unity, and it's very handy since it's kind of hard to do on your own. Especially when you don't know what you're doing... like me.

[swarnimarun]

Read this, we have a look at the function for the most basic 3D node Spatial.
http://docs.godotengine.org/en/3.0/classes/class_spatial.html#class-spatial-look-at

[ghost]

@swarnimarun I'm aware of that, but that isn't quite what this is asking for. look_at is for aligning a transform toward a point in space, but what I'm asking for here is just an easy way to rotate a vector toward (or away from) another, along a plane that consists of the two vectors. In practice, this would be a way to bypass the need to learn about the cross product.

[BastiaanOlij]

From the top of my head (there might be typos in here):

# normalise both vectors:
var va_n = va.normalized()
var vb_n = vb.normalized()

# take the cross product and dot product
var cross = va_n.cross(vb_n).normalized()
var dot = va_n.dot(vb_n)

# acos(dot) gives you the angle (in radians) between the two vectors which you'll want to clamp to your maximum rotation (convert it to radians)
var angle = clamp(acos(dot), -max, max)

# and now you can rotate your original 
var result = va.rotated(cross, angle)

[ghost]

@KellyThomas Oh wow, I didn't even know Vector3.slerp() existed... I'm pretty stupid!

To calculate t based on a max rotation delta, I think I can just do this: clamp(inverse_lerp(0, v1.angle_to(v2), max_delta), -1, 1).

I think I can create a function in a utility singleton that does this... or, I can just use @BastiaanOlij's code that he posted as I was writing this!!! Either way, this probably isn't needed anymore.