-------------------------------------------------------------------------------
-- Spine Runtimes License Agreement
-- Last updated May 1, 2019. Replaces all prior versions.
--
-- Copyright (c) 2013-2019, Esoteric Software LLC
--
-- Integration of the Spine Runtimes into software or otherwise creating
-- derivative works of the Spine Runtimes is permitted under the terms and
-- conditions of Section 2 of the Spine Editor License Agreement:
-- http://esotericsoftware.com/spine-editor-license
--
-- Otherwise, it is permitted to integrate the Spine Runtimes into software
-- or otherwise create derivative works of the Spine Runtimes (collectively,
-- "Products"), provided that each user of the Products must obtain their own
-- Spine Editor license and redistribution of the Products in any form must
-- include this license and copyright notice.
--
-- THIS SOFTWARE IS PROVIDED BY ESOTERIC SOFTWARE LLC "AS IS" AND ANY EXPRESS
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-- OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
-- NO EVENT SHALL ESOTERIC SOFTWARE LLC BE LIABLE FOR ANY DIRECT, INDIRECT,
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-- BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, BUSINESS
-- INTERRUPTION, OR LOSS OF USE, DATA, OR PROFITS) HOWEVER CAUSED AND ON ANY
-- THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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-------------------------------------------------------------------------------

local interpolation = {}

local math_pow = math.pow

function interpolation.apply (func, start, _end, a)
	return start + (_end - start) * func(a)
end

function interpolation.pow2(a)
	if (a <= 0.5) then return math_pow(a * 2, 2) / 2 end
	return math_pow((a - 1) * 2, 2) / -2 + 1
end

function interpolation.pow2out(a)
	return math_pow(a - 1, 2) * -1 + 1
end

return interpolation