54 lines
1.4 KiB
Plaintext
54 lines
1.4 KiB
Plaintext
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-- A tiny library for picking random values between two numbers using bézier curves
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-- Written in Lua by Singustromo
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-- Based on and inspired by randomizing_functions from Demonized
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-- Usage
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--[[
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local randomizer = libmath_bezier
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local a = randomizer.get_random_value(min, max, {p0, p1, p2, p3})
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--]]
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-- Pick a random float between min_cond and max_cond
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-- random value will be picked according to the function graph
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function get_random_value(min_cond, max_cond, params)
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local min_cond = min_cond or 0
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local max_cond = max_cond or 1
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if not params or type(params) ~= 'table' or #params < 3 then
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params = {0,0.5,1} -- linear interpolation
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end
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local rand = 1
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if #params == 4 then
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rand = cubic_bezier(math.random(), params)
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elseif #params == 3 then
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rand = quadratic_bezier(math.random(), params)
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end
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if (not rand) then return end
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if min_cond > max_cond then
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max_cond, min_cond = min_cond, max_cond
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end
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local a = max_cond - min_cond
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local b = a * rand
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local c = min_cond + b
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return c
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end
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function quadratic_bezier(x, p)
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-- linear interpolation: saving compute time
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if p[1] == 0 and p[2] == 0.5 and p[3] == 1 then return x end
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return p[1]*(1-x)^2 + 2*p[2]*x*(1-x) + p[3]*x^2
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end
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function cubic_bezier(x, p)
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-- linear interpolation: saving compute time
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if p[1] == 0 and p[2] == 1 and p[3] == 0 and p[4] == 1 then
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return x
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end
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return p[1]*(1-x)^3 + 3*p[2]*(1-x)^2*x + 3*p[3]*(1-x)*x^2 + p[4]*x^3
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end
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