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A Million Thanks!
Where did you learn 3d Geometry? I need to go there!
David Fontaine wrote:
> If you have triangle ABC, the cross-product of A-C (CA) and B-C (CB) will
> give you a vector perpendicular to the triangle. Cross-product of <u,v,w>
> and <x,y,z> is <vz-wy,wx-uz,uy-vx>. The x,y,z components of this new
> vector are the coefficients for the equation of a plane, Ax+By+Cz=D. To
> find D, plug one of the original points in for x, y and z. Now that we
> have the equation, it is simply a matter of solving for y: y=(D-Ax-Cz)/B
>
> double GetY(double Ax, double Ay, double Az,
> double Bx, double By, double Bz,
> double Cx, double Cy, double Cz,
> double _X, double _Z)
> {
> double _A, _B, _C, _D;
>
> _A = (Ay-Cy)*(Bz-Cz) - (Az-Cz)*(By-Cy);
> _B = (Az-Cz)*(Bx-Cx) - (Ax-Cx)*(Bz-Cz);
> _C = (Ax-Cx)*(By-Cy) - (Ay-Cy)*(Bx-Cx);
> _D = _A*Ax + _B*Ay + _C*Az;
> return (_D - _A*_X - _C*_Z) / _B;
> }
>
> --
> David Fontaine <dav### [at] faricy net> ICQ 55354965
> My raytracing gallery: http://davidf.faricy.net/
--
Bryan Valencia
www.eloan.com
925-560-2661
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