ColorSequenceLerp.lua

local BLACK_COLOR3 = Color3.new()

local function SortByTime(A, B)
	return A.Time < B.Time
end

local function Color3Lerp(C0, C1)
	local L0, U0, V0
	local R0, G0, B0 = C0.R, C0.G, C0.B
	R0 = R0 < 0.0404482362771076 and R0 / 12.92 or 0.87941546140213 * (R0 + 0.055) ^ 2.4
	G0 = G0 < 0.0404482362771076 and G0 / 12.92 or 0.87941546140213 * (G0 + 0.055) ^ 2.4
	B0 = B0 < 0.0404482362771076 and B0 / 12.92 or 0.87941546140213 * (B0 + 0.055) ^ 2.4

	local Y0 = 0.2125862307855956 * R0 + 0.71517030370341085 * G0 + 0.0722004986433362 * B0
	local Z0 = 3.6590806972265883 * R0 + 11.4426895800574232 * G0 + 4.1149915024264843 * B0
	local _L0 = Y0 > 0.008856451679035631 and 116 * Y0 ^ (1 / 3) - 16 or 903.296296296296 * Y0

	if Z0 > 1E-15 then
		local X = 0.9257063972951867 * R0 - 0.8333736323779866 * G0 - 0.09209820666085898 * B0
		L0, U0, V0 = _L0, _L0 * X / Z0, _L0 * (9 * Y0 / Z0 - 0.46832)
	else
		L0, U0, V0 = _L0, -0.19783 * _L0, -0.46832 * _L0
	end

	local L1, U1, V1
	local R1, G1, B1 = C1.R, C1.G, C1.B
	R1 = R1 < 0.0404482362771076 and R1 / 12.92 or 0.87941546140213 * (R1 + 0.055) ^ 2.4
	G1 = G1 < 0.0404482362771076 and G1 / 12.92 or 0.87941546140213 * (G1 + 0.055) ^ 2.4
	B1 = B1 < 0.0404482362771076 and B1 / 12.92 or 0.87941546140213 * (B1 + 0.055) ^ 2.4

	local Y1 = 0.2125862307855956 * R1 + 0.71517030370341085 * G1 + 0.0722004986433362 * B1
	local Z1 = 3.6590806972265883 * R1 + 11.4426895800574232 * G1 + 4.1149915024264843 * B1
	local _L1 = Y1 > 0.008856451679035631 and 116 * Y1 ^ (1 / 3) - 16 or 903.296296296296 * Y1

	if Z1 > 1E-15 then
		local X = 0.9257063972951867 * R1 - 0.8333736323779866 * G1 - 0.09209820666085898 * B1
		L1, U1, V1 = _L1, _L1 * X / Z1, _L1 * (9 * Y1 / Z1 - 0.46832)
	else
		L1, U1, V1 = _L1, -0.19783 * _L1, -0.46832 * _L1
	end

	return function(Alpha)
		local L = (1 - Alpha) * L0 + Alpha * L1
		if L < 0.0197955 then
			return BLACK_COLOR3
		end

		local U = ((1 - Alpha) * U0 + Alpha * U1) / L + 0.19783
		local V = ((1 - Alpha) * V0 + Alpha * V1) / L + 0.46832

		local Y = (L + 16) / 116
		Y = Y > 0.206896551724137931 and Y * Y * Y or 0.12841854934601665 * Y - 0.01771290335807126
		local X = Y * U / V
		local Z = Y * ((3 - 0.75 * U) / V - 5)

		local R = 7.2914074 * X - 1.5372080 * Y - 0.4986286 * Z
		local G = -2.1800940 * X + 1.8757561 * Y + 0.0415175 * Z
		local B = 0.1253477 * X - 0.2040211 * Y + 1.0569959 * Z

		if R < 0 and R < G and R < B then
			R, G, B = 0, G - R, B - R
		elseif G < 0 and G < B then
			R, G, B = R - G, 0, B - G
		elseif B < 0 then
			R, G, B = R - B, G - B, 0
		end

		R = R < 3.1306684425E-3 and 12.92 * R or 1.055 * R ^ (1 / 2.4) - 0.055
		G = G < 3.1306684425E-3 and 12.92 * G or 1.055 * G ^ (1 / 2.4) - 0.055
		B = B < 3.1306684425E-3 and 12.92 * B or 1.055 * B ^ (1 / 2.4) - 0.055

		R = R > 1 and 1 or R < 0 and 0 or R
		G = G > 1 and 1 or G < 0 and 0 or G
		B = B > 1 and 1 or B < 0 and 0 or B

		return Color3.new(R, G, B)
	end
end

local function ColorSequenceLerp(V0, V1)
	return function(Alpha)
		local keypoints = {}
		local addedTimes = {}
		local keylength = 0

		for _, ap in ipairs(V0.Keypoints) do
			local closestAbove, closestBelow

			for _, bp in ipairs(V1.Keypoints) do
				if bp.Time == ap.Time then
					closestAbove, closestBelow = bp, bp
					break
				elseif bp.Time < ap.Time and (closestBelow == nil or bp.Time > closestBelow.Time) then
					closestBelow = bp
				elseif bp.Time > ap.Time and (closestAbove == nil or bp.Time < closestAbove.Time) then
					closestAbove = bp
				end
			end

			local bValue
			if closestAbove == closestBelow then
				bValue = closestAbove.Value
			else
				bValue = Color3Lerp(closestBelow.Value, closestAbove.Value)((ap.Time - closestBelow.Time) / (closestAbove.Time - closestBelow.Time))
			end

			keylength += 1
			keypoints[keylength] = ColorSequenceKeypoint.new(ap.Time, Color3Lerp(ap.Value, bValue)(Alpha))
			addedTimes[ap.Time] = true
		end

		for _, bp in ipairs(V1.Keypoints) do
			if not addedTimes[bp.Time] then
				local closestAbove, closestBelow

				for _, ap in ipairs(V0.Keypoints) do
					if ap.Time == bp.Time then
						closestAbove, closestBelow = ap, ap
						break
					elseif ap.Time < bp.Time and (closestBelow == nil or ap.Time > closestBelow.Time) then
						closestBelow = ap
					elseif ap.Time > bp.Time and (closestAbove == nil or ap.Time < closestAbove.Time) then
						closestAbove = ap
					end
				end

				local aValue
				if closestAbove == closestBelow then
					aValue = closestAbove.Value
				else
					aValue = Color3Lerp(closestBelow.Value, closestAbove.Value)((bp.Time - closestBelow.Time) / (closestAbove.Time - closestBelow.Time))
				end

				keylength += 1
				keypoints[keylength] = ColorSequenceKeypoint.new(bp.Time, Color3Lerp(bp.Value, aValue)(Alpha))
			end
		end

		table.sort(keypoints, SortByTime)
		return ColorSequence.new(keypoints)
	end
end