3D Bezier angle at point

p5.js Libraries
1

Does anyone knows how to calculate angle at a particular point in 3D bezier curve ?

For example, consider there’s a ring to be inserted in BezierCurve. So can I get angles that ring makes in order for it to be parallel to the Bezier curve ?

2

By “ring” do you mean a circle, or an annulus?

By “parallel”, do you mean:

  1. a circle that is tangent to the curve – the circumference of the circle touches the curve at one point?
  2. OR: the centerpoint of the circle lies on the curve?
  3. or something else?

Maybe share a drawing.

3

By “ring”, I do mean ‘annulus’ or torus.

By “parallel”, I mean the center of that annulus lies on the curve and also that annulus follows the curve. So if the curve is bent at 45degrees, I want that annulus to bet at 45 degrees. Hope I was able to make my point this time :sweat_smile:. Only problem I am facing right now is that I have implemented Bezier curve in 3D space, am not able to get around that angle thing in 3D space.

4

Maybe you need to use PTF? (Parallel Transport Frames). That’s what you use to generate tubes and avoiding sudden flips of those rings in the middle of the tube. I think both HeMesh and ToxicLibs provide tube generation. I have ported this addon from C++ to Java in the past: https://github.com/neilmendoza/ofxPtf (I think I had to invert the matrices to make it work in Processing).

Is that the kind of thing you want to do?

2 Likes
5

Yes, this is what I was looking for. Thanks for helping me out of this sinkhole. But it will take me few days to digest this Physics ! BTW you should also port ofxPtf to Javascript too. Thanks for the help mate !