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glrandom.h

00001 /*--License:
00002         Kyra Sprite Engine
00003         Copyright Lee Thomason (Grinning Lizard Software) 2001-2002
00004         www.grinninglizard.com/kyra
00005         www.sourceforge.net/projects/kyra
00006 
00007         Kyra is provided under 2 licenses:
00008 
00009         - The GPL, with no additional restrictions.
00010         - The LGPL, provided you display the Kyra splash screen, described below.
00011 
00012 
00013 --- GPL License --
00014         This program is free software; you can redistribute it and/or
00015         modify it under the terms of the GNU General Public License
00016         as published by the Free Software Foundation; either version 2
00017         of the License, or (at your option) any later version.
00018 
00019         This program is distributed in the hope that it will be useful,
00020         but WITHOUT ANY WARRANTY; without even the implied warranty of
00021         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00022         GNU General Public License for more details.
00023 
00024         You should have received a copy of the GNU General Public License
00025         along with this program; if not, write to the Free Software
00026         Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
00027 
00028         The full text of the license can be found in license.txt
00029 
00030 
00031 --- LGPL License --
00032   **Provided you kindly display the Kyra splash screen (details below), 
00033         you     may use the LGPL license:**
00034 
00035     This library is free software; you can redistribute it and/or
00036     modify it under the terms of the GNU Lesser General Public
00037     License as published by the Free Software Foundation; either
00038     version 2.1 of the License, or (at your option) any later version.
00039 
00040     This library is distributed in the hope that it will be useful,
00041     but WITHOUT ANY WARRANTY; without even the implied warranty of
00042     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00043     Lesser General Public License for more details.
00044 
00045     You should have received a copy of the GNU Lesser General Public
00046     License along with this library; if not, write to the Free Software
00047     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00048 
00049         The full text of the license can be found in lgpl.txt
00050 
00051 
00052 --- Kyra Splash Screen.
00053 
00054         It would be appreciate if you display the Kyra splash screen when using
00055         either license, however it is only required for the LGPL. All the
00056         resources for the splash are compiled into the library, and it can be
00057         accessed through the following API:
00058 
00059                 KrEngine::StartSplash
00060                 KrEngine::UpdateSplash
00061                 KrEngine::EndSplash
00062 
00063         Full documentation is provided with the KrEngine class. The splash screen
00064         should be displayed for 2 seconds.
00065 
00066         Thank you.
00067 */
00068 
00069 #ifndef GL_RANDOM_INCLUDED
00070 #define GL_RANDOM_INCLUDED
00071 
00072 #include "gltypes.h"
00073 #include "gldebug.h"
00074 #include <stdlib.h>
00075 
00081 class GlRandom
00082 {
00083   public:
00085         GlRandom( U32 _seed = 0 );
00086 
00092         void SetSeed( U32 _seed );
00093 
00095         U16 Rand()                                              { return Randomize();   }
00099         U16 Rand( U16 upperBound )              { return Randomize() % upperBound; }
00100 
00104         U16 RandD2( U16 upperBound )    { U16 d1 = upperBound / 2 + 1;
00105                                                                           U16 d2 = upperBound - d1 + 1;
00106                                                                           U16 r  = Rand( d1 ) + Rand( d2 );
00107                                                                           GLASSERT( r < upperBound );
00108                                                                           return r;
00109                                                                         }
00110 
00114         U16 RandD3( U16 upperBound )    { U16 d1 = upperBound / 3 + 2;
00115                                                                           U16 d2 = upperBound / 3 + 2;
00116                                                                           U16 d3 = upperBound - d1 - d2 + 2;
00117                                                                           U16 r = Rand( d1 ) + Rand( d2 ) + Rand( d3 );
00118                                                                           GLASSERT( r < upperBound );
00119                                                                           return r;
00120                                                                         }
00121 
00123         double DRand( double upper )    { return upper * double( Randomize() ) / 65535.0; }
00124 
00126         float FRand( float upper )              { return upper * float( Randomize() ) / 65535.0f; }
00127 
00129         bool Boolean()                                  { return Rand( 100 ) >= 50; }
00130 
00131   private:
00132         U32 seed;
00133         inline void CalcSeed()          { seed = seed * 39421 + 1; }
00134         U16 Randomize();
00135 
00136         enum {
00137                 TABLESIZE = 16,
00138                 SLOTWIDTH = 0x10000 / TABLESIZE
00139         };
00140 
00141         U16 seedTable[ TABLESIZE ];
00142 };
00143 
00144 
00145 #endif

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