r15 mirror

-- Table containing the paired names of the body parts, NOT the names of the joints
local bodyPartPairs = {
	{"Head"},
	{"UpperTorso"},
	{"LowerTorso"},
	{"LeftUpperArm", "RightUpperArm"},
	{"LeftLowerArm", "RightLowerArm"},
	{"LeftHand", "RightHand"},
	{"LeftUpperLeg", "RightUpperLeg"},
	{"LeftLowerLeg", "RightLowerLeg"},
	{"LeftFoot", "RightFoot"}
}

-- Private
function MirrorPoseCFrame(cf)
	local x, y, z, R00, R01, R02, R10, R11, R12, R20, R21, R22 = cf:components()
	x = -x
	-- R00, R10, R20 (x)
	R10 = -R10
	R20 = -R20
	-- R01, R11, R21 (y)
	R01 = -R01
	-- R02, R12, R22 (z)
	R02 = -R02

	return CFrame.new(x, y, z, R00, R01, R02, R10, R11, R12, R20, R21, R22)
end

function GetKeyframeSequenceLength(keyframeSequence)
	local keyframes = keyframeSequence:GetChildren()
	local max = keyframes[1].Time
	for i, v in pairs(keyframes) do
		if v.Time > max then
			max = v.Time
		end
	end
	return max
end

function MirrorKeyframe(keyframe)
	for i, v in pairs(bodyPartPairs) do
		if #v == 1 then
			local pose = keyframe:FindFirstChild(v[1], true)
			if pose then
				pose.CFrame = MirrorPoseCFrame(pose.CFrame)
			end
		elseif #v == 2 then
			local leftName = v[1]
			local rightName = v[2]
			local leftPose = keyframe:FindFirstChild(leftName, true)
			local rightPose = keyframe:FindFirstChild(rightName, true)
			if leftPose and rightPose then
				leftPose.Name = rightName
				rightPose.Name = leftName
				leftPose.CFrame = MirrorPoseCFrame(leftPose.CFrame)
				rightPose.CFrame = MirrorPoseCFrame(rightPose.CFrame)
			elseif leftPose then
				leftPose.Name = rightName
				leftPose.CFrame = MirrorPoseCFrame(leftPose.CFrame)
			elseif rightPose then
				rightPose.Name = leftName
				rightPose.CFrame = MirrorPoseCFrame(rightPose.CFrame)
			end
		end
	end
end

-- Public
-- Precondition: ONLY Keyframes to be flipped are in the KeyframeSequence
-- Postcondition: The Keyframes are flipped and appended to the end of the KeyframeSequence
local MIRROR_GAP = 0.1667 -- how far apart the unmirrored and mirrored parts are
function SymmetricKeyframeSequence(keyframeSequence)
	local length = GetKeyframeSequenceLength(keyframeSequence)
	for i, v in pairs(keyframeSequence:GetChildren()) do
		local keyframeClone = v:Clone()
		keyframeClone.Name = v.Name .. "_mirrored"
		keyframeClone.Time = length + keyframeClone.Time + MIRROR_GAP
		MirrorKeyframe(keyframeClone)
		keyframeClone.Parent = keyframeSequence
	end
end

local dummy = game.Workspace.Player1
local animSaves = dummy.AnimSaves
local keyframeSequenceOrig = animSaves["mirrortest"]
local keyframeSequenceClone = keyframeSequenceOrig:Clone()
SymmetricKeyframeSequence(keyframeSequenceClone)
keyframeSequenceClone.Name = keyframeSequenceOrig.Name .. "_symmetric"
keyframeSequenceClone.Parent = animSaves