-- A tiny library for picking random values between two numbers using bézier curves
-- Written in Lua by Singustromo
-- Based on and inspired by randomizing_functions from Demonized

-- Usage
--[[
	local randomizer = libmath_bezier
	local a = randomizer.get_random_value(min, max, {p0, p1, p2, p3})
--]]

-- Pick a random float between min_cond and max_cond
-- random value will be picked according to the function graph
function get_random_value(min_cond, max_cond, params)
	local min_cond = min_cond or 0
	local max_cond = max_cond or 1

	if not params or type(params) ~= 'table' or #params < 3 then
                params = {0,0.5,1} -- linear interpolation
        end

	local rand = 1
	if #params == 4 then
		rand = cubic_bezier(math.random(), params)
	elseif #params == 3 then
		rand = quadratic_bezier(math.random(), params)
	end
	if (not rand) then return end

	if min_cond > max_cond then
		max_cond, min_cond = min_cond, max_cond
	end

	local a = max_cond - min_cond
	local b = a * rand
	local c = min_cond + b
	return c
end

function quadratic_bezier(x, p)
	-- linear interpolation: saving compute time
	if p[1] == 0 and p[2] == 0.5 and p[3] == 1 then	return x end

	return p[1]*(1-x)^2 + 2*p[2]*x*(1-x) + p[3]*x^2 
end

function cubic_bezier(x, p)
	-- linear interpolation: saving compute time
	if p[1] == 0 and p[2] == 1 and p[3] == 0 and p[4] == 1 then
		return x
	end
	
	return p[1]*(1-x)^3 + 3*p[2]*(1-x)^2*x + 3*p[3]*(1-x)*x^2 + p[4]*x^3
end