xdecor.box = {
	slab_y = function(height, shift)
		return {-0.5, -0.5 + (shift or 0), -0.5, 0.5, -0.5 + height +
			(shift or 0), 0.5}
	end,
	slab_z = function(depth)
		return {-0.5, -0.5, -0.5 + depth, 0.5, 0.5, 0.5}
	end,
	bar_y = function(radius)
		return {-radius, -0.5, -radius, radius, 0.5, radius}
	end,
	cuboid = function(radius_x, radius_y, radius_z)
		return {-radius_x, -radius_y, -radius_z, radius_x, radius_y, radius_z}
	end
}

xdecor.nodebox = {
	regular = {type="regular"},
	null = {type="fixed", fixed={0,0,0,0,0,0}}
}

xdecor.pixelbox = function(size, boxes)
	local fixed = {}
	for _, box in pairs(boxes) do
		-- `unpack` has been changed to `table.unpack` in newest Lua versions.
		local x, y, z, w, h, l = unpack(box)
		fixed[#fixed+1] = {
			(x / size) - 0.5,
			(y / size) - 0.5,
			(z / size) - 0.5,
			((x + w) / size) - 0.5,
			((y + h) / size) - 0.5,
			((z + l) / size) - 0.5
		}
	end
	return {type="fixed", fixed=fixed}
end

local mt = {}
mt.__index = function(table, key)
	local ref = xdecor.box[key]
	local ref_type = type(ref)

	if ref_type == "function" then
		return function(...)
			return {type="fixed", fixed=ref(...)}
		end
	elseif ref_type == "table" then
		return {type="fixed", fixed=ref}
	elseif ref_type == "nil" then
		error(key.."could not be found among nodebox presets and functions")
	end

	error("unexpected datatype "..tostring(type(ref)).." while looking for "..key)
end

setmetatable(xdecor.nodebox, mt)