Grass Culling

--!native
--!strict
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local CollectionService = game:GetService("CollectionService")

local Camera = workspace.CurrentCamera

local originalParents = {}

local function switchToCulledParent(obj: BasePart): ()
	if obj.Parent and obj.Parent ~= ReplicatedStorage.InteractiveGrass.CulledGrass then
		originalParents[obj] = obj.Parent
		obj.Parent = ReplicatedStorage.InteractiveGrass.CulledGrass
	end
end

local function switchToOriginalParent(obj: BasePart): ()
	local originalParent = originalParents[obj]
	if originalParent and obj.Parent == ReplicatedStorage.InteractiveGrass.CulledGrass then
		obj.Parent = originalParent
		originalParents[obj] = nil
	end
end

local function updateVisibility(): ()
	local viewDirection = Camera.CFrame.LookVector.Unit

	local function processObject(obj: BasePart): ()
		local partPosition = obj.Position
		local toObject = (partPosition - Camera.CFrame.Position).Unit
		local dotProduct = viewDirection:Dot(toObject)

		if dotProduct > 0 then
			switchToOriginalParent(obj)
		else
			switchToCulledParent(obj)
		end
	end
	for _, obj in CollectionService:GetTagged("Grass") do
		processObject(obj)
	end
end

Camera:GetPropertyChangedSignal("CFrame"):Connect(function()
	updateVisibility()
end)