如何在Lua中生成平铺Perlin噪声？

Question

所有我此刻的这个烂摊子代码：http://pastebin.com/F9Dc7pbR

这是不是平铺，也不漂亮（你必须把我的话，因为我不能将它张贴由于口碑）。

我还发现了噪音这个例子代码，将瓷砖：http://pastebin.com/cmuTBSJY

但我不能使用，因为我不知道Python或它如何转化到Lua。有任何想法吗？

编辑：澄清，它需要能够回绕到和触摸本身的X & Y轴两

Answer 1

这里张贴在转换到Lua问题的Python代码。它产生的噪音平铺：

-- Create 256 shuffled numbers 
local perm = {} 
for i = 1, 256 do 
    table.insert(perm, math.random(#perm + 1), i) 
end 

-- Repeat the list 
for i = 1, 256 do 
    perm[i+256] = perm[i] 
end 

-- Generate 256 directions 
local dirs = {} 
for a = 0, 255 do 
    table.insert(dirs, { math.cos(a * 2.0 * math.pi/256), 
         math.sin(a * 2.0 * math.pi/256) }) 
end 

local function noise(x, y, per) 
    local function surflet(grid_x, grid_y) 
     local dist_x, dist_y = math.abs(x - grid_x), math.abs(y - grid_y) 
     local poly_x = 1 - 6 * dist_x^5 + 15 * dist_x^4 - 10 * dist_x^3 
     local poly_y = 1 - 6 * dist_y^5 + 15 * dist_y^4 - 10 * dist_y^3 
     local hashed = perm[(perm[(math.floor(grid_x) % per) + 1] + math.floor(grid_y) % per) + 1] 
     local grad = (x - grid_x) * dirs[hashed][1] + (y - grid_y) * dirs[hashed][2] 
     return poly_x * poly_y * grad 
    end 
    local int_x, int_y = math.floor(x), math.floor(y) 
    return surflet(int_x+0, int_y+0) + surflet(int_x+1, int_y+0) + 
      surflet(int_x+0, int_y+1) + surflet(int_x+1, int_y+1) 
end 

local function fBm(x, y, per, octs) 
    local val = 0 
    for o = 0, octs - 1 do 
     val = val + (0.5^o * noise(x * 2^o, y * 2^o, per * 2^o)) 
    end 
    return val 
end 

local size, freq, octs = 128, 1/32.0, 5 

-- Generate 128x128 data points 
local data = {} 
for y = 1, size do 
    local line = {} 
    for x = 1, size do 
     table.insert(line, math.floor((fBm(x*freq, y*freq, math.floor(size*freq), octs) + 1) * 128)) 
    end 
    table.insert(data, line) 
end 

-- To demonstrate, let's generate a PGM file, 
-- which is easy to convert to PNG. 
local out = { "P2", "128 128", "255" } 
for y = 1, size do 
    local line = {} 
    for x = 1, size do 
     table.insert(line, tostring(data[y][x])) 
    end 
    table.insert(out, table.concat(line, " ")) 
end 
local pgm_data = table.concat(out, "\n") .. "\n" 

-- And now let's convert it to PNG using ImageMagick. 

-- We'll try to do it natively, loading https://github.com/leafo/magick 
-- To use it, install it with `luarocks install magick` 
-- and run this script with `luajit`. 
local ok, magick = pcall(require, "magick") 
if ok then 
    local im = magick.load_image_from_blob(pgm_data) 
    im:set_format("pgm") 
    im:write("noise.png") 
else 
    -- If we don't have the library, let's just call ImageMagick from the command-line. 
    local fd = io.open("noise.pgm", "w") 
    fd:write(pgm_data) 
    fd:close() 
    os.execute("convert noise.pgm noise.png") 
end