y coordinate for a given x cubic bezier

Question

This question is very similar to: Quadratic bezier curve: Y coordinate for a given X?. But this one is cubic...

I\'m using the getBezier function to calculate the Y

Answer 1

The original answer already contains everything you need to know

There are numerical issues. The exact solution for cubics suffers from stability problems.

The smooth geometric nature of typical Bezier curves means that spacial search (recursive subdivision) converges nicely, it's usually "fast enough", and it extends easily to N dimensions. There's quite a readable implementation in the Qt source code.