算法 – 包裹2D perlin噪声

wrappable_perlin_octave(grid,sizE):
   for (x=0;x<256;x+=sizE):
     for (y=0;y<256;y+=sizE):
       grid[x][y] = random()
   for (x=0;x<256;x+=sizE):
     for (y=0;y<256;y+=sizE):
       if (x % size != 0 || y % size != 0): # interpolate
         ax = x - x % size
         bx = (ax + sizE) % 256 # wrap-around
         ay = y - y % size
         by = (ay + sizE) % 256 # wrap-around
         h = (x % sizE) / size # horizontal balance,floaTing-point calculation
         v = (y % sizE) / size # vertical balance,floaTing-point calculation
         grid[x][y] = grid[ax][ay] * (1-h) * (1-v) +
                      grid[bx][ay] * h * (1-v) +
                      grid[ax][by] * (1-h) * v +
                      grid[bx][by] * h * v