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/* normals, Copyright (c) 2002-2021 Jamie Zawinski <jwz@jwz.org>
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation. No representations are made about the suitability of this
* software for any purpose. It is provided "as is" without express or
* implied warranty.
*
* Compute normal vectors for arbitrary triangles.
*/
#ifndef __NORMALS_H__
#define __NORMALS_H__
typedef struct {
double x,y,z;
} XYZ;
/* Calculate the unit normal at p given two other points p1,p2 on the
surface. The normal points in the direction of p1 crossproduct p2
*/
extern XYZ calc_normal (XYZ p, XYZ p1, XYZ p2);
/* Call glNormal3f() with a normal of the indicated triangle.
*/
extern void do_normal (GLfloat x1, GLfloat y1, GLfloat z1,
GLfloat x2, GLfloat y2, GLfloat z2,
GLfloat x3, GLfloat y3, GLfloat z3);
#endif /* __NORMALS_H__ */
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