/****************************************************************************
**
**  File:  v4cross.c                              Author:  Steve Hollasch
**
**      This routine forms the cross product of three 4-vectors.  Note that
**    the destination vector may be one of the source vectors.
**
****************************************************************************/

#include <vector.h>


void  V4_Cross  (result,u,v,w)
   Vector4  result;		/* Result Vector */
   Vector4  u, v, w;		/* Source Vectors */
{
   auto Real     A, B, C, D, E, F;	/* Intermediate Values */
   auto Vector4  temp;			/* Intermediate Vector */

   A = (v[0] * w[1]) - (v[1] * w[0]);
   B = (v[0] * w[2]) - (v[2] * w[0]);
   C = (v[0] * w[3]) - (v[3] * w[0]);
   D = (v[1] * w[2]) - (v[2] * w[1]);
   E = (v[1] * w[3]) - (v[3] * w[1]);
   F = (v[2] * w[3]) - (v[3] * w[2]);

   temp[0] =   (u[1] * F) - (u[2] * E) + (u[3] * D);
   temp[1] = - (u[0] * F) + (u[2] * C) - (u[3] * B);
   temp[2] =   (u[0] * E) - (u[1] * C) + (u[3] * A);
   temp[3] = - (u[0] * D) + (u[1] * B) - (u[2] * A);

   V4_2Vec (result,=,temp);
}