Okay first of all, I am trying to implement the Perlin noise algorithm, and I managed to achived something strange, and I can't find the solution. I am using matlab to visualize the results I have already checked this question:
I am doing it from this website:
And another website which I can't find right now but I will update as soon as I can.
So here are some pictures about the problem:
This is the problem if increase zoom https://i.sstatic.net/KkD7u.png
And here are the .cpp-s:
//perlin.cpp
#include "Perlin_H.h"
#include <stdlib.h>
#include <math.h>
#include <iostream>
#include <random>
using namespace std;
double Perlin::interp1(double a, double b, double x) {
double ft = x * 3.1415927;
double f = (1.0-cos(ft)) * 0.5;
//return (b-x > b-1/2) ? b-x : a+x;
return a * (1.0-f) + b * f;
}
double Perlin::smoothNoise(double x,double y) {
double corners = ( rand2(x-1, y-1)+rand2(x+1, y-1)+rand2(x-1, y+1)+rand2(x+1, y+1) ) / 16;
double sides = ( rand2(x-1, y) +rand2(x+1, y) +rand2(x, y-1) +rand2(x, y+1) ) / 8;
double center = rand2(x,y)/4;
return corners + sides +center;
}
double Perlin::lininterp1(double a,double b, double x) {
return a*(1-x) + b * x;
}
double Perlin::rand2(double x, double y) {
int n = (int)x + (int)y*57;
//n=pow((n<<13),n);
n=(n<<13)^n;
return ( 1.0 - ( (n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0);
}
double Perlin::noise(double x, double y) {
double floorX = (double)floor(x);
double floorY = (double)floor(y);
double s,t,u,v;
s = smoothNoise(floorX,floorY);
t = smoothNoise(floorX+1,floorY);
u = smoothNoise(floorY,floorY+1);
v = smoothNoise(floorX+1,floorY+1);
double int1 = interp1(s,t,x-floorX);
double int2 = interp1(u,v,x-floorX);
return interp1(int1,int2,y-floorY);
}
//main.cpp
#include "Perlin_H.h"
#include <stdlib.h>
#include <math.h>
#include <iostream>
#include <fstream>;
using namespace std;
int main() {
const int h=64,w=64,octaves=2;
double p=1/1;
double zoom = 30;
Perlin perlin;
double map[h][w];
ofstream output;
output.open("map.txt");
for(int i = 0; i < h ; i++) {
for(int j = 0; j < w ; j++) {
map[i][j] = 0;
}
}
double freq = 2;
for(int i = 0; i < h ; i++) {
for(int j = 0; j < w ; j++) {
double getnoise = 0;
for(int a=0; a < octaves; a++) {
double freq = pow(2,a);
double amp = pow(p,a);
getnoise = perlin.noise((((double)i)*freq)/zoom-(a*10),
((((double)j))*freq)/zoom+(a*10))*amp;
int color = (int)((getnoise * 128.0) + 128.0);
if(color > 255) color = 255;
if(color < 0) color = 0;
map[i][j] = color;
}
output << map[i][j] << "\t";
}
output << "\n";
}
output.close();
system("PAUSE");
return 0;
}
It's a typo!
s = smoothNoise(floorX,floorY); t = smoothNoise(floorX+1,floorY); u = smoothNoise(floorY,floorY+1); v = smoothNoise(floorX+1,floorY+1);
Try:
u = smoothNoise(floorX, floorY +1)
This explains why the diagonal didn't have the blocky appearance (where x=y), and why many of the common feature shapes are subtly off in a mirrored and skewed fashion. Since it is generally obvious that rand2(floor(y), floor(y)+1) != rand2(floor(x), floor(y+1)) the cell discontinuity will result.