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

[Nathan Hurst]

presumably you round 'outwards from the centre'?

njh



On Mon, 23 Apr 2001, Tom Kacvinsky wrote:

> 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
> >
> >
> 
> 
> _______________________________________________
> Devel mailing list
> address@hidden
> http://www.freetype.org/mailman/listinfo/devel
>