Convert gamma and magnitude values to a vector

[nemyax]

For a 2D animation spline, A:M stores the bias as gamma and magnitude. What are those values and how do I convert them to a 2D vector?

Apparently the gamma is the value of a trigonometric function, but which one?

[Rodney]

I'll take a stab...

 

I'm not sure how to convert them to a 2D vector but the the alpha and gamma settings indicate the degree of the axis for a spline passing through a control point. Gamma states one axis and alpha states the other.

 

If we view the values of bias as residing on a plane we should be able to determine the first (alpha) in terms of depth.and the second (gamma) in terms of breadth.

The issue with converting both into a 2D vector would be that they aren't both in the same 2D plane but are perpendicular to each other.

 

Convert the degrees into vectors (but keep the two separate) and then you have your 2D vectors.

 

 

I'll stop there before I hurt myself.

 

Edit: In re-reading your post it appears you might be talking about the splines found in the channels of the Timeline. If that is case then we'd have all our values confined within a 2D plane.

[nemyax]

the alpha and gamma settings indicate the degree of the axis for a spline passing through a control point

What's a "degree of the axis"?

[Fuchur]

I'd say it is the delta to the "normal" tangent of the curve at that point, but someone else with more math skills than mine needs to shine in to confirm that...

[nemyax]

I think I've got it.

In gamma is the angle between in_handle_vector and (prev_cp_vector - cp_vector).

Out gamma is the angle between out_handle_vector and (next_cp_vector - cp_vector).

Magnitude is tied to the distance between neighbouring CPs, and 300 (3.0) is the full distance for some reason.

[Rodney]

and 300 (3.0) is the full distance for some reason.

 

I wonder if this relates to your previous observation about FPS always being calculated in decimal increments of 30... even when set to other FPS rates.

[nemyax]

Isn't A:M's default bias handle length one-third of the CP-to-CP distance?

[robcat2075]

Isn't A:M's default bias handle length one-third of the CP-to-CP distance?

 

It looks that way on straight lines but maybe not on curves?