kingdoms_game/mods/utils/random.lua

--[[
Copyright (c) 2015, Robert 'Bobby' Zenz
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
--]]


--- Random is a static utility that provides fast and easy access to
-- random numbers.
random = {
	--- The internal maximum value.
	max = 2147483646,
	
	--- The internal minimum value.
	min = 0,
	
	--- The provider for random numbers.
	random_provider = nil
}


--- Initializes random. Should not be called from the client.
function random.init()
	if PcgRandom ~= nil then
		random.random_provider = PcgRandom(os.time())
	else
		math.randomseed(os.time())
		
		random.random_provider = {
			next = function(self, lower_bound, upper_bound)
				return math.abs(math.random(lower_bound, upper_bound))
			end
		}
	end
end

--- Returns true or false based on the given chance.
--
-- @param chance Optional. The "one in chance" chance to get true, defaults
--               to 2 (ans in "one in two").
-- @return true or false based in the given chance.
function random.next_bool(chance)
	chance = chance or 2
	
	if chance <= 0 then
		return false
	elseif chance == 1 then
		return true
	end
	
	return random.next_int(0, chance) == chance - 1
end

--- Returns a float between the given bounds.
--
-- @param lower_bound Optional. The lower bound (inclusive), defaults to 0.
-- @param upper_bound Optional. The upper bound (inclusive), defaults to 1.
-- @param decimal_places Optional. To how many decimal places the resulting
--                       float should be rounded.
-- @return a float between the given bounds.
function random.next_float(lower_bound, upper_bound, decimal_places)
	lower_bound = lower_bound or 0
	upper_bound = upper_bound or 1.0
	
	local value = random.random_provider:next(random.min, random.max)
	value = (value - random.min) / (random.max - random.min)
	value = value * (upper_bound - lower_bound) + lower_bound
	
	if decimal_places then
		value = mathutil.round(value, decimal_places)
	end
	
	return value
end

--- Returns an int between the given bounds.
--
-- @param lower_bound Optional. The lower bound (inclusive), defaults to
--                    random.min.
-- @param upper_bound Optional. The upper bound (inclusive), defaults to
--                    random.max.
-- @return a integer between the given bounds.
function random.next_int(lower_bound, upper_bound)
	lower_bound = lower_bound or random.min
	upper_bound = upper_bound or random.max
	
	return random.random_provider:next(lower_bound, upper_bound)
end


-- Initialize the random object.
random.init()