Quote: "it is not that I am not willing to modify my model as you said, the fact is that I do not know how to do it in 3ds max?."
OK, now we are getting somewhere. There is no shame in not knowing how to do something. This is why we learn if we are willing.
I must go to work right now. I will put something together to get you started. This is not a five minute job. This may take you a few days to get it into GG intact and functioning.
If we are going to take the time in splitting the mesh then we might as well do the whole thing proper, Including the textures.
Do you want this for PBR or for the DX9 way of diffuse, normal, spec, illum (DNSI) as it is referred to now here?
In a paint program that has .dds capability. GIMP, Photoshop, Paintnet, Paintshop Pro.
.DDS texture format is the fastest format for a game engine to digest and spit back out in the render pipeline.
Sizes are limited to multiples of 2. 512 x 512, 1024 x 512, 2048 x 2048, and so on up to 8K 8192 x 8192
Combine all the color textures into on sheet for remapping in 3ds max.
For DNSI format label your final texture sheets like this:
Yourtexture_D.dds Color texture
Yourtexture_N.dds Normal texture
Yourtexture_S.dds Specular texture
Yourtexture_i.dds Illumination texture
Yourtexture_cube.dds For cubemaps for reflection. Must be a real cube map
For PBR support label your final textures this way:
Yourtexture_color.dds dxt1 compression, can have an alpha channel for transparencies.
Yourtexture_normal.dds R8G8B8A8 export
Yourtexture_gloss.dds dxt1 compression Greyscale only.
Yourtexture_illumination.dds dxt1 compression White is what will illuminate, delete all else in texture.
Yourtexture_metalness.dds dxt1 compression Greyscale only.
Yourtexture_ao.dds dxt1 compression Greyscale only.
Yourtexture_height.dds dxt1 compression Greyscale only.
Yourtexture_cube.dds Must be a real cubemap to work
Once you have these maps made, then we can split the mesh in 3ds max and re uv map the islands to the new texture location.
Place the existing textures into the same spaces on each of the new maps you will be creating.
I will check back in at lunch time on your progress.
Here is some more relevant info for Game Guru models. This is how it works here.
Metalness - black is dialectric, White is metal
Gloss - Black is shiney, white is rough
Specular - Mostly grey scale except for metalic objects, then the reflectence color of the metal is used for the specular color (DNSI).
Roughness - Black is Rough, White is shiny - GG does not use this map.
Displacement - White is height, black is lows - experimental shader available, but not main stream yet.
Normal direction +X -Y +Z
--- #define RealisticVsCool (0.60) ---
Allows you to control some of the PBR light and light extractions from the environment , if you want it to look more like UE try to set it around 0.90 , if you want a Unity PBR look try to set it around 0.40. I made it like this , as i expect people will have different expectations for PBR.
--- #define AmountExtractLight (0.50) ---
This allow you to control the extraction of light , this is actually the sun from your skybox that you see on your car , so what you see is light extraction. to lower the intensity of the sun you can just lower this value.
Forgot to move those to settings.fx , so currently there are inside "apbr_core.fx"."
Axis directio in GG
Pos y - up
Neg Y - Down
Pos X - Right
Neg X - Left
Pos z - Forward
Neg Z - Back
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