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104 lines
2.3 KiB
104 lines
2.3 KiB
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RANDOM_CALLS_COUNT = 0
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-- https://stackoverflow.com/a/32387452/12464892
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local function bitwise_and(a, b)
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local result = 0
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local bit = 1
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while a > 0 and b > 0 do
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if a % 2 == 1 and b % 2 == 1 then
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result = result + bit
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end
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bit = bit * 2 -- shift left
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a = math.floor(a/2) -- shift-right
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b = math.floor(b/2)
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end
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return result
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end
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-- https://stackoverflow.com/a/20177466/12464892
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local A1, A2 = 727595, 798405 -- 5^17=D20*A1+A2
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local D20, D40 = 1048576, 1099511627776 -- 2^20, 2^40
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local X1, X2 = 0, 1
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local function rand()
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local U = X2*A2
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local V = (X1*A2 + X2*A1) % D20
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V = (V*D20 + U) % D40
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X1 = math.floor(V/D20)
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X2 = V - X1*D20
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return V/D40
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end
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local SEED_BOUNDS = 2^20 - 1
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local function randomseed2(seed)
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-- 0 <= X1 <= 2^20-1, 1 <= X2 <= 2^20-1 (must be odd!)
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-- ensure the number is odd, and within bounds of the generator
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local seed = bitwise_and(seed, 1)
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local v = math.clamp(math.abs(seed), 0, SEED_BOUNDS)
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X1 = v
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X2 = v + 1
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end
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local R = math.random
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local RS = math.randomseed
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local function random(n, m)
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RANDOM_CALLS_COUNT = RANDOM_CALLS_COUNT + 1
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local r
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if n then
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if m then
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r = math.floor(R() * (m - n) + n)
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else
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r = math.floor(R() * n)
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end
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else
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r = R()
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end
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return r
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end
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math.randomseed = function(seed)
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RANDOM_CALLS_COUNT = 0
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R = am.rand(seed)
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math.random = random
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end
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-- whenever we refer to math.random, actually use the function 'random' above
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math.random = random
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function g_octave_noise(x, y, num_octaves, seed)
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local seed = seed or os.time()
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local noise = 0
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for oct = 1, num_octaves do
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local f = 1/4^oct
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local l = 2^oct
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local pos = vec2(x + seed, y + seed)
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noise = noise + f * math.simplex(pos * l)
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end
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return noise
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end
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-- @TODO test, fix
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function poisson_knuth(lambda)
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local e = 2.71828
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local L = e^-lambda
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local k = 0
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local p = 1
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while p > L do
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k = k + 1
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p = p * math.random()
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end
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return k - 1
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end
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-- seed the random number generator with the current time
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-- os.clock() is better if the program has been running for a little bit.
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math.randomseed(os.time())
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