Re: [Devel] Problems with bbox code and cubic bezier curves

[Tom Kacvinsky]

I thought the point was to avoid square roots, because this introduces
16.16 fixed numbers.  Do we round, truncate, floor, or ceil such beasties?
Etc, etc...

Toby who?  It's been a while since I read the thread on bbox code.

On Mon, 23 Apr 2001, Nathan Hurst wrote:

> Toby pointed out that the bounding box of a bezier can be computed by
> computing the max and min of the x and y coords of the parametric equation
> of the curve, which for a cubic would occur at either the end points or
> the solutions of:
> t^2[A-3B-C-3D] + t[2B+6D] + [C-3D]
> where A,B,C,D are the x or y coords of the control points.
>
> This requires 2 sqrts per curve, but I suspect that that would be cheaper
> than an unknown number of splits?
>
> njh
>
>