Re: [Algorithms] How to get 3dvector largest coordinate index?

[Matt J <mjo...@gm...>]

Hmm, I fail to see how this works:

If (y > x) == 0 then that means x <= y.

So,

If x <= y and z < y then 0 << 0 = 0
If x <= y and z >= y then 0 << 1 = 0

In the first case, y is the greatest component In the second case, z is the
greatest component.

Both are encoded as 0. Something I'm missing?


Hi,
>
> I need to compute the index (not the actual value) of the largest
> coordinate of a normal, for some space hashing.
>
> I'm not sure how fast you guys usually find this index, but I've just
> created the following trick which I think is quite fast:
>
> > inline uint LargestCoordinate(const Vector3d &v)
> > {
> >       const float x = fabs(v.x);
> >       const float z = fabs(v.z);
> >       const float y = Maths::max( fabs(v.y), z );
> >       return uint(fabs(y)>fabs(x)) << uint(fabs(z)>=fabs(y));
> > }
>