Camelot: wxOil/mtrand.cpp (r1785/r751) Source File

00001 // $Id: mtrand.cpp 751 2006-03-31 15:43:49Z alex $
00002 // mtrand.cpp : Defines the entry point for the console application.
00003 //
00004 /* @@tag:xara-cn-tp@@ THIRD PARTY COPYRIGHT */
00005 #include "camtypes.h"
00006 #include "mtrand.h"
00007 
00008 UINT32 MTRand::lastSeed = 1;
00009 
00010 /********************************************************************************************
00011 
00012 >   UINT32 MTRand::GetNextRandomNumberScaled(UINT32 MaxValue, UINT32 MinValue)
00013 
00014     Author:     Gerry_Iles (Xara Group Ltd) <camelotdev@xara.com>
00015     Created:    04/11/2005
00016     Inputs:     -
00017     Returns:    the next number in an already seeded random number sequence, scaled to between
00018                 the two specified values
00019     Purpose:    as above, note that you MUST have already seeded the sequence
00020     SeeAlso:
00021 
00022 ********************************************************************************************/
00023 
00024 UINT32 MTRand::GetNextRandomNumberScaled(UINT32 MaxValue, UINT32 MinValue)
00025 {
00026     UINT32 Random =  this->operator ()();
00027     double ScaleFactor = ((double)(MaxValue - MinValue)) / ((double)MTRAND_MAX);
00028     double Res = (double)Random * ScaleFactor;
00029     return (UINT32)Res + MinValue;
00030 }
00031 
00032 
00033 /********************************************************************************************
00034 
00035 >   UINT32 MTRand::GetNextRandomNumberScaled(UINT32 MaxValue, UINT32 MinValue, UINT32 Median)
00036 
00037     Author:     Gerry_Iles (Xara Group Ltd) <camelotdev@xara.com>
00038     Created:    04/11/2005
00039     Inputs:     MaxValue - the top of our random range
00040                 MinValue - the bottom of our random range
00041                 Median - duh
00042     Returns:    the next number in an already seeded random number sequence, scaled to between
00043                 the two specified values
00044     Purpose:    Overridden version which allows you to have a non-linear range.  By specifying the
00045                 median all random values > MTRAND / 2 will be scaled from Median - MaxValue and
00046                 all random values <= MTRAND / 2 will be scaled from MinValue - Median.
00047     SeeAlso:
00048 
00049 ********************************************************************************************/
00050 
00051 UINT32 MTRand::GetNextRandomNumberScaled(UINT32 MaxValue, UINT32 MinValue, UINT32 Median)
00052 {
00053     UINT32 Random = rand();
00054 
00055     UINT32 Retval = 0;
00056     if (Random < MTRAND_MED)
00057     {
00058         double ScaleFactor = ((double)(Median - MinValue)) / (double)MTRAND_MED;
00059         double Res = ScaleFactor * Random;
00060         Retval = (UINT32)Res + MinValue;
00061     }
00062     if (Random >= MTRAND_MED)
00063     {
00064         double ScaleFactor = ((double)(MaxValue - Median)) / (double)MTRAND_MED;
00065         double Res = ScaleFactor * (Random - MTRAND_MED);
00066         Retval = (UINT32)Res + Median;
00067     }
00068     return Retval;
00069 }