如何实现2D单纯形噪声/ 2D Perlin噪声（C ++ 11）

Question

我的问题是我不知道如何将单面噪声/ perlin噪声值插入到我的世界生成器中以产生更好看的景观，是否有人可以显示简单的代码来展示如何实现它。

顺便说一下，我是编程新手，所以任何答案都会受到赞赏，这对我有很大帮助。

下面是代码：

noise.h

#pragma once

class PerlinNoise
{
public:

  // Constructor
    PerlinNoise();
    PerlinNoise(double _persistence, double _frequency, double _amplitude, int _octaves, int _randomseed);

  // Get Height
    double GetHeight(double x, double y) const;

  // Get
  double Persistence() const { return persistence; }
  double Frequency()   const { return frequency;   }
  double Amplitude()   const { return amplitude;   }
  int    Octaves()     const { return octaves;     }
  int    RandomSeed()  const { return randomseed;  }

  // Set
  void Set(double _persistence, double _frequency, double _amplitude, int _octaves, int _randomseed);

  void SetPersistence(double _persistence) { persistence = _persistence; }
  void SetFrequency(  double _frequency)   { frequency = _frequency;     }
  void SetAmplitude(  double _amplitude)   { amplitude = _amplitude;     }
  void SetOctaves(    int    _octaves)     { octaves = _octaves;         }
  void SetRandomSeed( int    _randomseed)  { randomseed = _randomseed;   }


    double Total(double i, double j) const;
    double GetValue(double x, double y) const;
    double Interpolate(double x, double y, double a) const;
    double Noise(int x, int y) const;

    double persistence, frequency, amplitude;
    int octaves, randomseed;
};

noise.cpp：

#include "noise.h"

PerlinNoise::PerlinNoise()
{
  persistence = 0;
  frequency = 0;
  amplitude  = 0;
  octaves = 0;
  randomseed = 0;
}

PerlinNoise::PerlinNoise(double _persistence, double _frequency, double _amplitude, int _octaves, int _randomseed)
{
  persistence = _persistence;
  frequency = _frequency;
  amplitude  = _amplitude;
  octaves = _octaves;
  randomseed = 2 + _randomseed * _randomseed;
}

void PerlinNoise::Set(double _persistence, double _frequency, double _amplitude, int _octaves, int _randomseed)
{
  persistence = _persistence;
  frequency = _frequency;
  amplitude  = _amplitude;
  octaves = _octaves;
  randomseed = 2 + _randomseed * _randomseed;
}

double PerlinNoise::GetHeight(double x, double y) const
{
  return amplitude * Total(x, y);
}

double PerlinNoise::Total(double i, double j) const
{
    //properties of one octave (changing each loop)
    double t = 0.0f;
    double _amplitude = 1;
    double freq = frequency;

    for(int k = 0; k < octaves; k++)
    {
        t += GetValue(j * freq + randomseed, i * freq + randomseed) * _amplitude;
        _amplitude *= persistence;
        freq *= 2;
    }

    return t;
}

double PerlinNoise::GetValue(double x, double y) const
{
    int Xint = (int)x;
    int Yint = (int)y;
    double Xfrac = x - Xint;
    double Yfrac = y - Yint;

  //noise values
  double n01 = Noise(Xint-1, Yint-1);
  double n02 = Noise(Xint+1, Yint-1);
  double n03 = Noise(Xint-1, Yint+1);
  double n04 = Noise(Xint+1, Yint+1);
  double n05 = Noise(Xint-1, Yint);
  double n06 = Noise(Xint+1, Yint);
  double n07 = Noise(Xint, Yint-1);
  double n08 = Noise(Xint, Yint+1);
  double n09 = Noise(Xint, Yint);

  double n12 = Noise(Xint+2, Yint-1);
  double n14 = Noise(Xint+2, Yint+1);
  double n16 = Noise(Xint+2, Yint);

  double n23 = Noise(Xint-1, Yint+2);
  double n24 = Noise(Xint+1, Yint+2);
  double n28 = Noise(Xint, Yint+2);

  double n34 = Noise(Xint+2, Yint+2);

    //find the noise values of the four corners
    double x0y0 = 0.0625*(n01+n02+n03+n04) + 0.125*(n05+n06+n07+n08) + 0.25*(n09);
    double x1y0 = 0.0625*(n07+n12+n08+n14) + 0.125*(n09+n16+n02+n04) + 0.25*(n06);
    double x0y1 = 0.0625*(n05+n06+n23+n24) + 0.125*(n03+n04+n09+n28) + 0.25*(n08);
    double x1y1 = 0.0625*(n09+n16+n28+n34) + 0.125*(n08+n14+n06+n24) + 0.25*(n04);

    //interpolate between those values according to the x and y fractions
    double v1 = Interpolate(x0y0, x1y0, Xfrac); //interpolate in x direction (y)
    double v2 = Interpolate(x0y1, x1y1, Xfrac); //interpolate in x direction (y+1)
    double fin = Interpolate(v1, v2, Yfrac);  //interpolate in y direction

    return fin;
}

double PerlinNoise::Interpolate(double x, double y, double a) const
{
    double negA = 1.0 - a;
  double negASqr = negA * negA;
    double fac1 = 3.0 * (negASqr) - 2.0 * (negASqr * negA);
  double aSqr = a * a;
    double fac2 = 3.0 * aSqr - 2.0 * (aSqr * a);

    return x * fac1 + y * fac2; //add the weighted factors
}

double PerlinNoise::Noise(int x, int y) const
{
    int n = x + y * 57;
    n = (n << 13) ^ n;
  int t = (n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff;
    return 1.0 - double(t) * 0.931322574615478515625e-9;/// 1073741824.0);
}

的main.cpp

#include "noise.h"
#include <iostream>
#include <stdlib.h>
#include <time.h>

using namespace std;

int main(){
    PerlinNoise pn;


    srand(time(NULL)); // Random
    for(int c = 1;c<=100;c++){
        int x = rand() % 10000;
        int y = rand() & 10000;
        double t = pn.Noise(x, y);
        if(t >= -1 && t <= -0.5){ // For Soil
            cout << "=";
        }else if(t >= -0.5 && t <= 0){ // For Stone
            cout << "+";
        }else if(t >= 0 && t <= 0.5){ // For Sand
            cout << "*";
        }else if(t >= 0.5 && t <= 1){ // For Lava
            cout << "#";
        }
        if(c%10 == 0){
            cout << '\n';
        }
    }
}

输出：

http://imgur.com/dEO5l0p

但我想要这种输出

http://imgur.com/ua3K1Xf

但我希望土壤位于最顶层并产生地形。