How can I force Unity to use my UV2 channel for lightmapping?

Unity Engine
1

Hi All,
Wondering what I’m doing wrong here, I have created 2 uv sets on my geomety in max
Set uv channel 1 for albedo information
Set uv channel 2 for light map - mapping geometry to reduce # of charts and hopefully clean up artifacts and help render times as suggested in the “viking lighting tutorial”
When I import into Unity I make sure “generate Lightmap UV’s” is unchecked.
I set everything up, and after scene is baked, I look at the charts in Lighting - Object Maps and the map has been split up to several charts and basically ignoring my UV2 channnel.
In my model I have originally 4 “islands” - unity is giving me roughly 12.

How can I force Unity to use my UV2 channel for lightmapping?
thanks for any help
Jinda

2

Hi @jinda_1

It seems like in your DCC package (your external 3D app), you’re not assigning it to correct channel, therefore Unity reads from the correct channel but incorrect data. For instance, there’s a way to check UV layouts in your UV channels in Maya through a Python script, I shared some details here: Progressive CPU Lightmapper page-6#post-3151080 You can check that post.

Thanks

3

I have a similar question.

My 3d scene has meshes that

  • have UV2 channel nicely unwrapped
  • don´t have UV2 channel at all

Now I want to lightbake the scene in Unity also including the meshes that do not have UV2 channel.
So I tick “Generate lightmap UVs” in Unity to ensure that all meshes have UV2.
But now my custom unwrapped meshes get overwritten by a new UV2 layout by Unity. :frowning:

I want Unity both to keep my own UV2 layouts and generate UV2 for missing UVs.
Not possible?

At least there should be a toggle “Keep existing UV2”, right?