#include <stdio.h>
#include <math.h>
#include <dos.h>
#include "tools.h"

float gauss(unsigned seed);
void subdivide (int f1, int f2, float std);

float Fh[257],ratio;
char combination= 0x00;
unsigned long int PATTERN=0xFFFFFFFF;
unsigned int seed=3245;
int LINEWIDTH = 1;

main()
{
	float scale=1000,h=.87,std;
	int i;

	while (seed != 0)
	{
		setMode(3);
		printf("Enter seed (0 to quit): ");
		scanf("%d",&seed);
		Fh[0] = gauss(seed) * scale;
		Fh[256] = gauss(0) * scale;
		ratio = pow(2,-h);
		std = scale*ratio;
		subdivide(0,256,std);
		setMode(16);
		for (i=0; i<256; i++)
			drawLine(2*i-260,Fh[i],2*(i+1)-260,Fh[i+1],15);
		PATTERN = 0x0F0F0F0F;
		drawLine(-260,0,252,0,15);
		PATTERN = 0xFFFFFFFF;
		getch();
	}
}

void subdivide (int f1, int f2, float std)
{
	int fmid;
	float stdmid;

	fmid = (f1 + f2)/2;
	if (( fmid != f1) && (fmid != f2))
	{
		Fh[fmid] = (Fh[f1] + Fh[f2])/2.0 + gauss(0) * std;
		stdmid = std*ratio;
		subdivide(f1,fmid,stdmid);
		subdivide(fmid,f2,stdmid);
	}
}

float gauss(unsigned seed)
{
	int k;
	float value,exponent,gauss;

	if (seed != 0)
		srand(seed);
	k = rand() - 16383;
	value = k/5461.0;
	exponent = -(value*value)/2.;
	gauss = .15915494*exp(exponent);
	k = rand();

	if (k > 16383)
		gauss *= -1;
	return(gauss);
}