Passing Variable To Table Function In Join

Hello, thanks in advance for reading this. I am having difficulty trying to get a statement to work.

There is a MAIN table:
ItemNo int identity(1,0),
ItemType tinyint

There is a WETPAINT table:
ItemNo int,
Color varchar(20)

There is a DRYPAINT table:
ItemNo int,
Color varchar(20)

Now, what I want to do is JOIN the MAIN table to either the WETPAINT table or the DRYPAINT table depending on the value of MAIN.ItemType

So I created a table function called getTable:

CREATE FUNCTION [dbo].[gettable]
(
@ItemType int = 1
)
RETURNS
@thistable TABLE
(
Color varchar(20)

)
AS
BEGIN
if @ItemType = 1
insert into @thistable (color) select color from WETPAINT
if @ItemType = 2
insert into @thistable (color) select color from DRYPAINT
RETURN
END

This is all fine and dandy if I iterate through the MAIN table one row at a time, but how can I JOIN the tables, like:

SELECT MAIN.ItemNo, a.Color
FROM MAIN
INNER JOIN gettable(Main.ItemNo) as a
ON a.ItemNo = MAIN.ItemNo

Obviously, there is more than one field in the DRYPAINT and WETPAINT tables, and there is a need to have both tables instead of combining them into one.

Any help in how to create a table alias by passing a value from the select statement would be greatly appreciated! Thanks again.

PS -- I am trying to create a view with this, so I can't use variables and iterate through the MAIN table one row at a time.