#ifndef NOISE_H#define NOISE_H// All noise amplitudes rannge between 0 and 1.// The inputs range between 0 and 1 (for the 1th octave, there is no 0th octave),// so the second octave is 1/2 and the third 1/4 etc.// Only the FillArray* functions use inputs between 0..Width and 0..Height// and return values between Min and Max.#include <stdlib.h>#include <iostream.h>#include <math.h>class cNoiseGen2D{public:	cNoiseGen2D()				{randseed = 0;}	cNoiseGen2D(int RandSeed)	{randseed = RandSeed;}	float Get(float x, float y)	{									srand( (int)(randseed + x * y * randseed) ); 									return ((float)(rand()%1000))/1000;								}	void Reset(int RandSeed)	{randseed = RandSeed;}private:	int randseed;};class cPerlin2D{public:	// constructor	cPerlin2D(int RandSeed, int Octaves, float Persistence) 		{			gen.Reset(RandSeed); 			octaves = Octaves; 			persistence = Persistence;			maxval = 0;			for (int i = 0; i <= octaves; i++)			{				maxval += pow(persistence, i);			}		}	// Sets the randseed.	void SetRandseed(int RandSeed) {gen.Reset(RandSeed);}	// the higher the persistence the less the amplitude of high freq noise lowers (1 is no lowering).	void SetPersistence(float Persistence)			{		persistence = Persistence;		maxval = 0;		for (int i = 0; i <= octaves; i++)		{			maxval += pow(persistence, i);		}	}	// the number of octaves.	void SetOctaves(int Octaves)					{		octaves = Octaves;		maxval = 0;		for (int i = 0; i <= octaves; i++)		{			maxval += pow(persistence, i);		}	}	// gets the value of the amplitude at x, y.	float Get(float x, float y);	// fills an array with the dimensions 0..width, 0.. height with random chars. (range 0..255)	bool FillArrayb(char * array[], int Width, int Height, char Min, char Max);	// fills an array with the dimensions 0..width, 0.. height with random ints. (range 0..10000)	bool FillArrayi(int * array[], int Width, int Height, int Min, int Max);	// fills an array with the dimensions 0..width, 0.. height with random floats. (range 0..1)	bool FillArrayf(float * array[], int Width, int Height, float Min, float Max);private:	// the function returns an interpolated value between I and J. Returns I when Fraction = 0 and J when Fraction = 1.	float InterpolateCos(float I, float J, float Fraction);	// returns the interpolated noise amplitude for a certain x and y.	float InterpolateNoise(float x, float y);	int octaves;	float maxval; // maxval is used to calculate the maximum value that Get can return, so it can be scaled back to 0..1	float persistence;	cNoiseGen2D gen;};#endif

#include "noise.h"float cPerlin2D::Get(float x, float y){	float total = 0;	float freq;	float amp;	for (int i = 0; i <= octaves; i++)	{		freq = pow(2, i);		amp = pow(persistence, i);		total += InterpolateNoise(x * freq, y * freq) * amp;	}	total /= maxval;	return total;}float cPerlin2D::InterpolateCos(float I, float J, float Fraction){	float ft = Fraction * 3.1415927f;	float f = (1.0f - cos(ft)) * 0.50f;	return (I*(1.0f-f) + J*f);}float cPerlin2D::InterpolateNoise(float x, float y){	int ix = int(x); // integer	float fx = x - ix; // fractional	int iy = int(y); // integer	float fy = y - iy; // fractional	float v1 = gen.Get(ix, iy);	float v2 = gen.Get(ix+1, iy);	float v3 = gen.Get(ix,	 iy+1);	float v4 = gen.Get(ix+1, iy+1);	float i1 = InterpolateCos(v1, v2, fx);	float i2 = InterpolateCos(v3, v4, fx);    return InterpolateCos(i1, i2, fy);}

float Get(float x, float y){	int n = x + y * 57;	n = (n<<13) ^ n;	float out = (1.0 - (float)((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0);    	// this returns a number between -1 and 1	out = (out + 1) / 2; // now 0..1	return out;}