Author : TomAnima


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skyline5gtr's Avatar
Old (#1)
Hey everyone , I'm part of a mod project called Star Trek Armada 3 for Sins of a Solar Empire, we were having problems with mirrored normal's and symmetry mesh and I was wondering if you could offer some help.

Long story short every time we make a model and symmetry it/Mirror it , in game it appear flipped or half the normals are flipped but when i preview it in marmoset or a preview its fine

Here is an example

Thanks Nick
Nick Barone - 3d Artist
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Noors's Avatar
Old (#2)
Are you talking about flipped normal map, or flipped mesh normals ? What software ?
If it's a normal map issue, it is engine/shader dependent. If you can't access it through mod, you're doomed. You have to unfold everything on 1 map.

If it is about the mesh, you have to use a resetXform, or freeze transform, or whatever your software calls it, and flip back the inverted normals. Softwares might display it right, but it isnt. Always freeze transform everything before dealing with normals.
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skyline5gtr's Avatar
Old (#3)
I'm not sure what the difference is

I personally use 3dsmax, this user used XSI cause you have to create tangants in XSI. Here is the process maybe it will clear it up.

Build half of the mesh/model
Unwrap it
Texture it
Apply Symmetry
Export

I think its an engine issue, but i don't understand why. Would offsetting the symmetry half uvs and flipping it work ? I don't understand if the model only uses 1 uv map and half a model why would it not be the same on the other (Symmetry side)

As you can see if the picture half of the Akira ships normal map is inverted, some of the details are going inward as oppose to outward.

Last edited by skyline5gtr; Yesterday at 11:59 AM..
Nick Barone - 3d Artist
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Noors's Avatar
Old (#4)
Ok, so it's a normal map issue.
You might want to reset xform the model after a symmetry tho. May cause normal issues.
Well i'm not a big techy, so this might not be entirely precise, but

Normal maps use a repair defined by vertex normal/tangent/binormal vectors.
Tangent is dependent of uv.
Symmetry in uv leads to a flipped repair => inverted normal map
The shader used in the engine might or not support it.

Do you know if existent ships in the game use symmetry in their texture ?

Last edited by Noors; Yesterday at 12:53 PM..
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skyline5gtr's Avatar
Old (#5)
Yes i was looking around through some of the references and i saw some of the textures on some ships, which were only half. SO its possible trying to figure if its in engine or something stupid we did lol
Nick Barone - 3d Artist
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