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-- 初始化种子表
local perm = {}
for i = 0, 255 do
perm[i] = i
end
for i = 0, 255 do
local j = math.random(0, 255)
perm[i], perm[j] = perm[j], perm[i]
end
for i = 0, 255 do
perm[i + 256] = perm[i]
end
-- 柏林噪声函数
---@param x number x坐标
---@param y number y坐标
---@param seed string 种子
---@return number -- 高度坐标
return function(x, y, seed)
if gameapi then
gameapi.set_random_seed(seed)
else
math.randomseed(tonumber(seed))
end
local function fade(t)
return t * t * t * (t * (t * 6 - 15) + 10)
end
local function lerp(t, a, b)
return a + t * (b - a)
end
local function grad(hash, x, y)
local h = hash % 16
local u = h < 8 and x or y
local v = h < 4 and y or ((h == 12 or h == 14) and x or 0)
return ((h % 2) == 0 and u or -u) + ((h % 3) == 0 and v or -v)
end
local function noise(x, y, perms)
local X = math.floor(x) % 256
local Y = math.floor(y) % 256
local xf = x - math.floor(x)
local yf = y - math.floor(y)
local u = fade(xf)
local v = fade(yf)
local AA = (perms[X % 256] + Y) % 256
local AB = (perms[(X + 1) % 256] + Y) % 256
local BA = (perms[X % 256] + Y + 1) % 256
local BB = (perms[(X + 1)] % 256 + Y + 1) % 256
local x1 = lerp(u, grad(perms[AA], xf, yf), grad(perms[AB], xf - 1, yf))
local x2 = lerp(u, grad(perms[BA], xf, yf - 1), grad(perms[BB], xf - 1, yf - 1))
return lerp(v, x1, x2)
end
return noise(x, y, perm)
end
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