CrystalSpace

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csgeom/math.h
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00001 /*
00002   Copyright (C) 2005 by Marten Svanfeldt
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_MATH_H__
00020 #define __CS_MATH_H__
00021 
00022 #include "csutil/algorithms.h"
00023 
00034 template<class T>
00035 const T& csMax (const T& a, const T& b)
00036 {
00037   if (b < a) return a;
00038   return b;
00039 }
00040 
00044 template<class T>
00045 const T& csMin (const T& a, const T& b)
00046 {
00047   if (a < b) return a;
00048   return b;
00049 }
00050 
00054 template<class T>
00055 void csSort (T& a, T& b)
00056 {
00057   if (b < a)
00058     CS::Swap (a, b);
00059 }
00060 
00065 template<class T, class U>
00066 void csSort (T& a, T& b, U& x, U& y)
00067 {
00068   if (b < a)
00069   {
00070     CS::Swap (a, b);
00071     CS::Swap (x, y);
00072   }
00073 }
00074 
00075 
00079 template<class T>
00080 T csClamp (const T& a, T max, T min)
00081 {
00082   return csMin (csMax (a, min), max);
00083 }
00084 
00090 template<class T>
00091 T csSmoothStep (const T& a, T max, T min)
00092 {
00093   T tmp, tmp2;
00094   if (a <= min)
00095     tmp = 0.0f;
00096   else if (a >= max)
00097     tmp = 1.0f;
00098   else
00099   {
00100     tmp2 = (a - min) / (max-min);
00101     tmp = tmp2*tmp2 * (3.0 - 2.0*tmp2);
00102   }
00103   return tmp;
00104 }
00105 
00110 template<class T, class Tfactor>
00111 T csLerp (const T& a, const T& b, const Tfactor& f)
00112 {
00113   return (a + (b - a) * f);
00114 }
00115 
00119 template<class T>
00120 T csSquare (const T& x)
00121 {
00122   return x * x;
00123 }
00124 
00125 namespace CS
00126 {
00129   /* IsNaN() is implemented by looking at the binary values directly
00130      as using built-in functions turned out to be unreliable.
00131      (Specifically, gcc's built-in isnan() always returns false if
00132      -ffast-math is enabled.) */
00134   CS_FORCEINLINE bool IsNaN (float f)
00135   {
00136   #ifdef CS_IEEE_DOUBLE_FORMAT
00137     const uint32 exponentMask = 0x7f800000;
00138     const uint32 mantissaMask = 0x007fffff;
00139     union
00140     {
00141       float f;
00142       uint32 ui32;
00143     } u;
00144     u.f = f;
00145     return ((u.ui32 & exponentMask) == exponentMask)
00146         && ((u.ui32 & mantissaMask) != 0);
00147   #else
00148     #error Do not know how to test for NaN
00149   #endif
00150   }
00151   // External definition; used below as a workaround for __STRICT_ANSI__
00152   CS_CRYSTALSPACE_EXPORT bool IsNaN_ext (double d);
00154   CS_FORCEINLINE bool IsNaN (double d)
00155   {
00156   #ifdef __STRICT_ANSI__
00157     return IsNaN_ext (d);
00158   #else
00159   #ifdef CS_IEEE_DOUBLE_FORMAT
00160     const uint64 exponentMask = CONST_UINT64(0x7ff0000000000000);
00161     const uint64 mantissaMask = CONST_UINT64(0x000fffffffffffff);
00162     union
00163     {
00164       double d;
00165       uint64 ui64;
00166     } u;
00167     u.d = d;
00168     return ((u.ui64 & exponentMask) == exponentMask)
00169         && ((u.ui64 & mantissaMask) != 0);
00170   #else
00171     #error Do not know how to test for NaN
00172   #endif
00173   #endif
00174   }
00175   
00177   CS_FORCEINLINE bool IsFinite (float f)
00178   {
00179   #ifdef CS_IEEE_DOUBLE_FORMAT
00180     const uint32 exponentMask = 0x7f800000;
00181     union
00182     {
00183       float f;
00184       uint32 ui32;
00185     } u;
00186     u.f = f;
00187     return ((u.ui32 & exponentMask) != exponentMask);
00188   #else
00189     #error Do not know how to test for NaN
00190   #endif
00191   }
00192   // External definition; used below as a workaround for __STRICT_ANSI__
00193   CS_CRYSTALSPACE_EXPORT bool IsFinite_ext (double d);
00195   CS_FORCEINLINE bool IsFinite (double d)
00196   {
00197   #ifdef __STRICT_ANSI__
00198     return IsFinite_ext (d);
00199   #else
00200   #ifdef CS_IEEE_DOUBLE_FORMAT
00201     const uint64 exponentMask = CONST_UINT64(0x7ff0000000000000);
00202     union
00203     {
00204       double d;
00205       uint64 ui64;
00206     } u;
00207     u.d = d;
00208     return ((u.ui64 & exponentMask) != exponentMask);
00209   #else
00210     #error Do not know how to test for NaN
00211   #endif
00212   #endif
00213   }
00214   
00216   CS_FORCEINLINE float Infinity()
00217   {
00218   #ifdef CS_IEEE_DOUBLE_FORMAT
00219     union
00220     {
00221       uint32 ui32;
00222       float f;
00223     } u;
00224     u.ui32 = 0x7f800000;
00225     return u.f;
00226   #else
00227     return std::numeric_limits<float>::infinity();
00228   #endif
00229   }
00231 } // namespace CS
00232 
00234 
00238 CS_DEPRECATED_METHOD_MSG("Use CS::IsFinite(x) instead")
00239 CS_FORCEINLINE bool csFinite (float f)
00240 {
00241   return CS::IsFinite (f);
00242 }
00247 CS_DEPRECATED_METHOD_MSG("Use CS::IsFinite(x) instead")
00248 CS_FORCEINLINE bool csFinite (double d)
00249 {
00250   return CS::IsFinite (d);
00251 }
00252 
00257 CS_DEPRECATED_METHOD_MSG("Use CS::IsNaN(x) instead")
00258 CS_FORCEINLINE bool csNaN (float f)
00259 {
00260   return CS::IsNaN (f);
00261 }
00266 CS_DEPRECATED_METHOD_MSG("Use CS::IsNaN(x) instead")
00267 CS_FORCEINLINE bool csNaN (double d)
00268 {
00269   return CS::IsNaN (d);
00270 }
00271 
00277 CS_DEPRECATED_METHOD_MSG("Usage not recommended, inconsistent results")
00278 CS_FORCEINLINE bool csNormal (float f)
00279 {
00280 #if defined (CS_HAVE_NORMALF)
00281   return normalf (f);
00282 #elif defined (CS_HAVE_STD__ISNORMAL)
00283   return std::isnormal (f);
00284 #elif defined(CS_HAVE_ISNORMAL)
00285   return isnormal (f);
00286 #else
00287   return CS::IsFinite(f) && !CS::IsNaN(f);
00288 #endif
00289 }
00295 CS_DEPRECATED_METHOD_MSG("Usage not recommended, inconsistent results")
00296 CS_FORCEINLINE bool csNormal (double d)
00297 {
00298 #if defined (CS_HAVE_STD__ISNORMAL)
00299   return std::isnormal (d);
00300 #elif defined(CS_HAVE_ISNORMAL)
00301   return isnormal (d);
00302 #else
00303   return CS::IsFinite(d) && !CS::IsNaN(d);
00304 #endif
00305 }
00307 
00308 
00309 namespace CS
00310 {
00311 namespace Math
00312 {
00314   template<typename T>
00315   CS_FORCEINLINE_TEMPLATEMETHOD T NextModulo3 (T number)
00316   {
00317     return (1 << number) & 0x3;
00318   }
00319 }
00320 }
00321 
00322 
00325 #endif //__CS_MATH_H__

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