Thanks for your answer but I already figured it out.
I was trying to get a cordinate system like blenders object cordinates where the center of the object has (0,0,0) value and the values increase as you move away from the object. My idea was to use VERTEX built-in but the values are not relative to the origin of the object. My mistake was thinking they in global cordinates but turns out they are actually in something called view space. So what I needed is to transform the VERTEX values to be in global space (which basically is global cordinates) then to local space to get my cordinate system. To do that you just multiply VERTEX with the inverse view matrix then inverse model matrix (world matrix in godot 3.4).
Anyway thanks for taking time to look at my question.