http://ftp.ksu.edu.tw/FTP/FreeBSD/distfiles/xscreensaver-4.20.tar.gz

[xscreensaver] / hacks / glx / normals.h

diff --git a/hacks/glx/normals.h b/hacks/glx/normals.h
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+/* normals, Copyright (c) 2002-2004 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__ */