CrystalSpace

Public API Reference

cstool/fogmath.h

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00001 /*
00002     Copyright (C) 2004 by Anders Stenberg
00003 
00004     This library is free software; you can redistribute it and/or
00005     modify it under the terms of the GNU Library General Public
00006     License as published by the Free Software Foundation; either
00007     version 2 of the License, or (at your option) any later version.
00008 
00009     This library is distributed in the hope that it will be useful,
00010     but WITHOUT ANY WARRANTY; without even the implied warranty of
00011     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012     Library General Public License for more details.
00013 
00014     You should have received a copy of the GNU Library General Public
00015     License along with this library; if not, write to the Free
00016     Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00017 */
00018 
00019 #ifndef __CS_CSTOOL_FOGMATH_H__
00020 #define __CS_CSTOOL_FOGMATH_H__
00021 
00026 
00027 class csFogMath
00028 {
00029 public:
00033   static inline float Ramp (float depth)
00034   {
00035     return 1.0 - exp (-depth*7);
00036     //return depth;
00037   }
00039   /* @@@ NOTE: Basically the same computation that's done when using fog
00040    * texgen from the glfixed VP - means, keep this function in sync! */
00041   static inline float OpacityAtDistance (float density, float dist)
00042   {
00043     return Ramp (density*(dist-0.1f));
00044   }
00046   static inline float DistanceForOpacity (float density, float opacity)
00047   {
00048     return -(log(-opacity+1.0f)/(density * 7.0f)) + 0.1f;
00049   }
00050 };
00051 
00052 
00053 #endif // __CS_CSTOOL_FOGMATH_H__
00054 

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