I made a basic tiling texture in photoshop and used NDO to generate a normal map.

Do I need to flip/invert the green channel in photoshop before using the normal map in UDK?

I tried it without flipping and Im pretty sure my normals are not quite right.

Any help appreciated.

Common sense rules here, wouldn't you say? If it doesn't look right, did you TRY flipping it and looking at it in UDK to see if it looked right?

By default, NDO settings will need to have inverted Y to look correct in UDK.

We learn best by trying, not by having our hands held. Just try it next time before posting something as easily solved as this!

Thanks for the response.

How do you invert the Y in photoshop?

Is Y the green channel?

Yeah, Y is the green channel. R = X, G = Y

You can change the NDO options to invert the Y coord on normal-creation, too. So you wouldn't have to deal with inverting at all.

Also, you can import the file again (don't reimport), giving a popup menu to import. One of the options is to invert green channel. You can do this if something looks wrong.

All in all, for UDk and Max, the normals should kind of look inverted (in terms of brights and darks), as if the green channel which is brighter, is the insetting edge (for example, a brick wall will looked pushed in rather than popped out.)

Import texture -> Tick box Flip Y Channel.

Or...

Import texture -> Save -> Put in Material Editor -> Take Green channel -> Multiply it by -1 -> Append RG -> Append B OR DeriveZ -> Connect to Material Normal.

Originally Posted by Ace-Angel

Import texture -> Tick box Flip Y Channel.

Or...

Import texture -> Save -> Put in Material Editor -> Take Green channel -> Multiply it by -1 -> Append RG -> Append B OR DeriveZ -> Connect to Material Normal.

Or...

Import texture -> Save -> Put in Material Editor -> Multiply it by (1, -1, 1) -> connect to material.

or...
go to the green channel and invert it in photoshop...

I honestly cannot believe that this is it's own thread.

you can flip it in PS before importing or make udk import flip it, or just setup xnormal and ndo up to work with -y.

i just set all my tools up to use -y, since UDK is my main game engine, and my viewport shader in maya supports both -y and +y


like Joshua Stubbles said, experiment, test things, problem solve before posting.

This thread is great!

Thanks for clearing that up and illuminating my mind.