Spring.lua

local Spring = {} do
	Spring.__index = Spring

	local pi = math.pi
	local exp = math.exp
	local sin = math.sin
	local cos = math.cos
	local sqrt = math.sqrt
	
	function Spring.new(dampingRatio, frequency, position)
		local self = setmetatable({}, Spring)
		
		assert(dampingRatio*frequency >= 0, 'stop that')

		self.d = dampingRatio -- damping ratio
		self.f = frequency -- nominal frequency
		self.g = position -- goal position
		self.p = position -- position
		self.v = position*0 -- velocity (times 0 so the types match)
		
		return self
	end

	function Spring:setGoal(g)
		self.g = g
	end
	
	function Spring:getState()
		return self.p, self.v
	end

	function Spring:step(dt)
		local d = self.d
		local f = self.f*2*pi
		local g = self.g
		local p = self.p
		local v = self.v

		local offset = p - g
		local decay = exp(-dt*d*f)

		-- Given:
		--   f^2*(x[dt] - g) + 2*d*f*x'[dt] + x''[dt] = 0,
		--   x[0] = p,
		--   x'[0] = v
		-- Solve for x[dt], x'[dt]
		
		if d == 1 then -- critically damped

			self.p = (v*dt + offset*(f*dt + 1))*decay + g
			self.v = (v - f*dt*(offset*f + v))*decay

		elseif d < 1 then -- underdamped

			local c = sqrt(1 - d*d)

			local i = cos(f*c*dt)
			local j = sin(f*c*dt)

			self.p = (i*offset + j*(v + d*f*offset)/(f*c))*decay + g
			self.v = (i*c*v - j*(v*d + f*offset))*decay/c

		elseif d > 1 then -- overdamped

			local c = sqrt(d*d - 1)

			local r1 = -f*(d - c)
			local r2 = -f*(d + c)

			local co2 = (v - r1*offset)/(2*f*c)
			local co1 = offset - co2

			local e1 = co1*exp(r1*dt)
			local e2 = co2*exp(r2*dt)
			
			self.p = e1 + e2 + g
			self.v = r1*e1 + r2*e2

		end
	end
end

return Spring

hmmmm yeah roblox defenetily didnt steal your code