Re: [Algorithms] Bicubic normals for a bicubic world

[John S. <jse...@ho...>]

How are the normals biquadratic? And the two tangent surfaces can't be
biquadratic, because you're only derivating in one parameter, leaving the
other as-is. You derive in u, it's still cubic in v, and vice-versa.

I really want to have a good solution to this, so please bear with me.

Thanks.

John Sensebe
jse...@ho...
Quantum mechanics is God's way of ensuring that we never really know what's
going on.

Check out http://members.home.com/jsensebe to see prophecies for the coming
Millennium!


----- Original Message -----
From: "Conor Stokes" <cs...@tp...>
To: <gda...@li...>
Sent: Friday, August 11, 2000 9:58 PM
Subject: Re: [Algorithms] Bicubic normals for a bicubic world


>     Actually, if you think about it - The normals are totally quadratic.
And
> if you do a derivitive in 2
> directions (across S, and across T) you do get 2 quadratics. Not only
that,
> the cross product is
> resiliant to transforms - So it remains the same. However, normalisation
> still needs to occur.
>
>     This is why I precalc my normals and reference them from a map in most
> cases.
>
> Conor Stokes
>
>