2 * The 3D Studio File Format Library
3 * Copyright (C) 1996-2001 by J.E. Hoffmann <je-h@gmx.net>
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU Lesser General Public License as published by
8 * the Free Software Foundation; either version 2.1 of the License, or (at
9 * your option) any later version.
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
14 * License for more details.
16 * You should have received a copy of the GNU Lesser General Public License
17 * along with this program; if not, write to the Free Software Foundation,
18 * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 * $Id: ease.c,v 1.4 2001/01/12 10:29:17 jeh Exp $
23 #include <lib3ds/ease.h>
29 * \author J.E. Hoffmann <je-h@gmx.net>
37 lib3ds_ease(Lib3dsFloat fp, Lib3dsFloat fc, Lib3dsFloat fn,
38 Lib3dsFloat ease_from, Lib3dsFloat ease_to)
44 s=step=(Lib3dsFloat)(fc-fp)/(fn-fp);
45 tofrom=ease_to+ease_from;
48 ease_to=(Lib3dsFloat)(ease_to/tofrom);
49 ease_from=(Lib3dsFloat)(ease_from/tofrom);
51 a=1.0/(2.0-(ease_to+ease_from));
53 if (step<ease_from) s=a/ease_from*step*step;
55 if ((1.0-ease_to)<=step) {
57 s=1.0-a/ease_to*step*step;
60 s=((2.0*step)-ease_from)*a;
64 return((Lib3dsFloat)s);