UVManager: several changes

- new doesn't use self
- better type checking for getUV
- make parameters for .new optional

UVManager.lua

@@ -10,11 +10,11 @@ UVManager = {
 }
 mt.__index=UVManager
 --- @return UVManager
---- @param step Vector2 A vector representing the distance between UVs
---- @param offset Vector2 A vector represnting the starting point for UVs, or nil
---- @param positions table A dictionary of names and offset vectors
---- @param part ModelPart Model part to manage
-function UVManager.new(self, step, offset, positions, part)
+--- @param step? Vector2 A vector representing the distance between UVs
+--- @param offset? Vector2 A vector represnting the starting point for UVs, or nil
+--- @param positions? table A dictionary of names and offset vectors
+--- @param part? ModelPart Model part to manage
+function UVManager.new(step, offset, positions, part)
 	local t={}
 	if step ~= nil then t.step=step end
 	if offset ~= nil then t.offset=offset end
@@ -34,15 +34,20 @@ function UVManager.setPart(self, part)
 	self.dimensions=part:getTextureSize()
 end
 
+
+---Get real UV from vec(x, y) or string representing preset
+---@param input Vector2|string UV to get
 function UVManager.getUV(self, input)
 	local vect={}
 	local stp=self.step
 	local offset=self.offset
+	assert(type(input)=="string" or type(input) == "Vector2")
 	if type(input) == "string" then
 		if self.positions[input] == nil then return nil end
 		vect=self.positions[input]
-	else
-		vect=vectors.of(input)
+	elseif type(input) == "Vector2" then
+		-- vect=vectors.of(input)
+		vect=input
 	end
 	local u=offset.x+(vect.x*stp.x)
 	local v=offset.y+(vect.y*stp.y)