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diff --git a/src/3dengfx/libs/lib3ds/ease.c b/src/3dengfx/libs/lib3ds/ease.c
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+++ b/src/3dengfx/libs/lib3ds/ease.c
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+/*
+ * The 3D Studio File Format Library
+ * Copyright (C) 1996-2001 by J.E. Hoffmann <je-h@gmx.net>
+ * All rights reserved.
+ *
+ * This program is  free  software;  you can redistribute it and/or modify it
+ * under the terms of the  GNU Lesser General Public License  as published by 
+ * the  Free Software Foundation;  either version 2.1 of the License,  or (at 
+ * your option) any later version.
+ *
+ * This  program  is  distributed in  the  hope that it will  be useful,  but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or  FITNESS FOR A  PARTICULAR PURPOSE.  See the  GNU Lesser General Public  
+ * License for more details.
+ *
+ * You should  have received  a copy of the GNU Lesser General Public License
+ * along with  this program;  if not, write to the  Free Software Foundation,
+ * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * $Id: ease.c,v 1.4 2001/01/12 10:29:17 jeh Exp $
+ */
+#define LIB3DS_EXPORT
+#include <lib3ds/ease.h>
+
+
+/*!
+ * \defgroup ease Ease
+ *
+ * \author J.E. Hoffmann <je-h@gmx.net>
+ */
+
+
+/*!
+ * \ingroup ease
+ */
+Lib3dsFloat
+lib3ds_ease(Lib3dsFloat fp, Lib3dsFloat fc, Lib3dsFloat fn,
+  Lib3dsFloat ease_from, Lib3dsFloat ease_to)
+{
+  Lib3dsDouble s,step;
+  Lib3dsDouble tofrom;
+  Lib3dsDouble a;
+
+  s=step=(Lib3dsFloat)(fc-fp)/(fn-fp);
+  tofrom=ease_to+ease_from;
+  if (tofrom!=0.0) {
+    if (tofrom>1.0) {
+      ease_to=(Lib3dsFloat)(ease_to/tofrom);
+      ease_from=(Lib3dsFloat)(ease_from/tofrom);
+    }
+    a=1.0/(2.0-(ease_to+ease_from));
+
+    if (step<ease_from) s=a/ease_from*step*step;
+    else {
+      if ((1.0-ease_to)<=step) {
+        step=1.0-step;
+        s=1.0-a/ease_to*step*step;
+      }
+      else {
+        s=((2.0*step)-ease_from)*a;
+      }
+    }
+  }
+  return((Lib3dsFloat)s);
+}