local module = {}
setmetatable(module, {__index=_G})
setfenv(1, module)

--===== transform cascading =====--

system = function(params)
	return {
		db = params.db,
		
		priority = 2,
		update = function(self, dt)
			local nodes = self.db:queryComponent("node")
	
			-- prepare nodes
			for id, node in pairs(nodes) do
				node._visited = false
			end
	
			-- helper function
			local function recursiveTransform(node)
				if node._visited then
					return node._matrix
				end
	
				if not node.parent then
					node._matrix = node.matrix
				else
					local parentTransform = self.db:getComponent(node.parent, "node")
					local parentMatrix = recursiveTransform(parentTransform)
					node._matrix = parentMatrix * node.matrix
				end
				node._visited = true
				return node._matrix
			end
	
			-- compute nodes
			for id, node in pairs(nodes) do
				recursiveTransform(node)
			end
		end,
	}
end



return module