Godot: Imported 3D model vertex positions suffer increasing distortion the further they are from the origin.

[K9Kraken]

Godot version:

3.0.2

OS/device including version:

Manjaro Linux 17.1.6

Issue description:

A model imported in to Godot that has vertices with floating point positions will shift slightly, 0.433 ends up being 0.4329.
I am using 3D tiles and so this ends up causing small visible seams or cracks in the terrain. I can currently fix this by either rounding the vertex positions or by iterating through all the vertices and snapping them.
I have tried exporting the models from Blender using Better Callada, OBJ, and glTF with the same result. Checking the OBJ file and it contains the correct/exact vertex positions.

Steps to reproduce:
Import a model in to Godot that contains vertices with a floating point value such as 0.433.
Check the vertex positions of the imported mesh and you will find they have shifted slightly.

UPDATE
This issue is worse than I had thought, the further a meshes vertex is from it's origin the worse it suffers position distortion, see new comment below. I also updated the title.

[Zireael07]

This is not limited to imported tiles - I am seeing the same minuscule cracks with geometry generated in editor. @K9Kraken thanks for making the issue, I wondered why they would happen and now I know!

[K9Kraken]

Did a few more tests and this issue is defiantly related to the SurfaceTool bug here: https://github.com/godotengine/godot/issues/17307
The further a vertex is from the origin the worse the distortion gets, this happens for imported models and models created with SurfaceTool; Geometry drawn with ImmediateGeometry does not suffer from this bug.

I created a hexagon in blender with the vertices 500 units from the origin on the x axis.

Here are the vertices in the exported obj file (They match the vertices in Blender):
(500.000000, 0.000000, 0.500000)
(500.000000, 0.000000, -0.500000)
(499.566986, 0.000000, -0.250000)
(500.433014, 0.000000, -0.250000)
(500.000000, 0.000000, -0.000000)
(499.566986, 0.000000, 0.250000)
(500.433014, 0.000000, 0.250000)

Here is the vertex array of the model after it is imported in to Godot:
(500, 0, 0)
(499.5, 0, -0.25)
(500, 0, -0.5)
(499.5, 0, 0.25)
(500.25, 0, 0.25)
(500.25, 0, -0.25)
(500, 0, 0.5)

The order of the vertices does not matter, but you can see some values are slightly distorted while others are highly distorted; as the distance increases the distortion gets worse.

This is how the model looks in blender or drawn with ImmediateGeometry in Godot:

This is how the model looks when imported in to Godot or created with SurfaceTool:

[reduz]

this is now fixed, it had to do with default compression using 16 bits vertices. It was removed.