The previous answered question doesn't seem to answer my problem "Blocky" Perlin noise

I tried to simplify the most I could to make my code readable and understandable.

I don't use the permutation table, instead I use the mt19937 generator.

I use SFML

using namespace std; using namespace sf; typedef Vector2f Vec2; Sprite spr; Texture tx; // dot product float prod(Vec2 a, Vec2 b) { return a.x*b.x + a.y*b.y; } // linear interpolation float interp(float start,float end,float coef){return coef*(end-start)+start;} // get the noise of a certain pixel, giving its relative value vector in the square with [0.0 1.0] values float getnoise(Vec2&A, Vec2&B, Vec2&C, Vec2&D, Vec2 rel){ float dot_a=prod(A ,Vec2(rel.x ,rel.y)), dot_b=prod(B ,Vec2(rel.x-1 ,rel.y)), dot_c=prod(C ,Vec2(rel.x ,rel.y-1)), dot_d=prod(D ,Vec2(rel.x-1 ,rel.y-1)); return interp (interp(dot_a,dot_b,rel.x),interp(dot_c,dot_d,rel.x),rel.y); // return interp // (interp(da,db,rel.x),interp(dc,dd,rel.x),rel.y); } // calculate the [0.0 1.0] relative value of a pixel Vec2 getrel(int i, int j, float cellsize){ return Vec2 (float (i // which pixel -(i/int(cellsize))//which cell *cellsize)// floor() equivalent /cellsize,// [0,1] range float(j-(j/int(cellsize))*cellsize)/cellsize ); } // generates an array of random float values vector<float> seeded_rand_float(unsigned int seed, int many){ vector<float> ret; std::mt19937 rr; std::uniform_real_distribution<float> dist(0, 1.0); rr.seed(seed); for(int j = 0 ; j < many; ++j) ret.push_back(dist(rr)); return ret; } // use above function to generate an array of random vectors with [0.0 1.0] values vector<Vec2>seeded_rand_vec2(unsigned int seed, int many){ auto coeffs1 = seeded_rand_float(seed, many*2); // auto coeffs2 = seeded_rand_float(seed+1, many); //bad choice ! vector<Vec2> pushere; for(int i = 0; i < many; ++i) pushere.push_back(Vec2(coeffs1[2*i],coeffs1[2*i+1])); // pushere.push_back(Vec2(coeffs1[i],coeffs2[i])); return pushere; } // here we make the perlin noise void make_perlin() { int seed = 43; int pixels = 400; // how many pixels int divisions = 10; // cell squares float cellsize = float(pixels)/divisions; // size of a cell auto randv = seeded_rand_vec2(seed,(divisions+1)*(divisions+1)); // makes the vectors be in [-1.0 1.0] range for(auto&a:randv) a = a*2.0f-Vec2(1.f,1.f); Image img; img.create(pixels,pixels,Color(0,0,0)); for(int j=0;j<=pixels;++j) { for(int i=0;i<=pixels;++i) { int ii = int(i/cellsize); // cell index int jj = int(j/cellsize); // those are the nearest gradient vectors for the current pixel Vec2 A = randv[divisions*jj +ii], B = randv[divisions*jj +ii+1], C = randv[divisions*(jj+1) +ii], D = randv[divisions*(jj+1) +ii+1]; float val = getnoise(A,B,C,D,getrel(i,j,cellsize)); val = 255.f*(.5f * val + .7f); img.setPixel(i,j,Color(val,val,val)); } } tx.loadFromImage(img); spr.setPosition(Vec2(10,10)); spr.setTexture(tx); };

Here are the results, I included the resulted gradients vector (I multiplied them by cellsize/2).

My question is why are there white artifacts, you can somehow see the squares...

PS: it has been solved, I posted the fixed source here http://pastebin.com/XHEpV2UP

Don't make the mistake of applying a smooth interp on the result instead of the coefficient. Normalizing vectors or adding an offset to avoid zeroes doesn't seem to improve anything. Here is the colorized result: