sampler.h

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/*
**  Command & Conquer Generals Zero Hour(tm)
**  Copyright 2025 Electronic Arts Inc.
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/***********************************************************************************************
 ***              C O N F I D E N T I A L  ---  W E S T W O O D  S T U D I O S               ***
 ***********************************************************************************************
 *                                                                                             *
 *                 Project Name : Sampler                                                      *
 *                                                                                             *
 *                     $Archive:: /VSS_Sync/wwlib/sampler.h                                   $*
 *                                                                                             *
 *              Original Author:: Hector Yee                                                   *
 *                                                                                             *
 *                      $Author:: Vss_sync                                                    $*
 *                                                                                             *
 *                     $Modtime:: 8/29/01 10:25p                                              $*
 *                                                                                             *
 *                    $Revision:: 1                                                           $*
 *                                                                                             *
 *---------------------------------------------------------------------------------------------*
 * Functions:                                                                                  *
 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
#if _MSC_VER >= 1000
#pragma once
#endif // _MSC_VER >= 1000
 
// 'function selected for automatic inline expansion'.  Cool, but since we're treating
// warnings as errors, don't warn me about this!
#pragma warning(disable : 4711)
 
// 'not inlined' -- the evil twin of the above warning.
#pragma warning(disable : 4710)
 
#ifndef SAMPLER_H
#define SAMPLER_H
 
class Random4Class;
 
// This module contains sampling techniques that sample over multidimensional space
// Dimension is the length of the vector to sample
// Divisions is used to determine the number of strata to sample over
// In some samplers, e.g. regular grid, it will repeat after dimension*division calls
// to sample. A call to sample increments the internal state of the sampler.
// Hector Yee 6/11/01
 
// Abstract base class
// all these sampling algoriths modify a vector of length Dimensions
// they all return a value between 0..1
// Hector Yee 6/11/01
class SamplingClass
{
public:
    SamplingClass(unsigned int dimensions, unsigned char divisions):
        Dimensions(dimensions),
        Divisions(divisions)
        {}; 
    virtual void Reset() {};
    virtual void Sample(float *target)=0;
    virtual ~SamplingClass() {};
protected:
    unsigned int Dimensions;
    unsigned char Divisions;
};
 
// Samples randomly in the dimensions using Mesenne Twister
// divisions ignored
// Hector Yee 6/11/01
class RandomSamplingClass : public SamplingClass
{
public:
    RandomSamplingClass(unsigned int dimensions, unsigned char divisions=0);
    virtual void Reset() {};
    virtual void Sample(float *target);   
};
 
// samples over a regular hypergrid
// Hector Yee 6/11/01
class RegularSamplingClass : public SamplingClass
{
public:
    RegularSamplingClass(unsigned int dimensions, unsigned char divisions=3);
    virtual void Reset();
    virtual void Sample(float *target);
    virtual ~RegularSamplingClass();
protected:
    unsigned char *index;
};
 
// samples over a regular hypergrid with random perturbations
// Hector Yee 6/11/01
class StratifiedSamplingClass : public SamplingClass
{
public:
    StratifiedSamplingClass(unsigned int dimensions, unsigned char divisions=3);
    virtual void Reset();
    virtual void Sample(float *target);
    virtual ~StratifiedSamplingClass();
protected:
    unsigned char *index;
};
 
// samples using QuasiMonteCarlo
// divisions ignored
// based on the Halton-Hammersly sequence which is in turn based on the inverse radical function
// Hector Yee 6/11/01
class QMCSamplingClass : public SamplingClass
{
public:
    QMCSamplingClass(unsigned int dimensions, unsigned char divisions=0);
    virtual void Reset() {index=0;};
    virtual void Sample(float *target);
    void Set_Offset(unsigned int offset) { index=offset; }
protected:
    unsigned int index;
};
 
 
#endif