Flatten Mapping

[Tim_Hobson]

@Querorz;220868

, thanks so much for all the detailed explanations and links. Here some new questions:

1- Is that “Generate Lighmap UVs” option necessary** only** if i didn’t unwrap a lightmap in ? Should i enable this option when i already unwrapped my own second channel UV in ?
2- When you use the modifier “UVW Map” in and select “Box” mode, it works for most of the objects. But why doesn’t it work in Unreal. Or does it ?

1. Yes if you want to have a lightmap with your static lighting. The answer is also, No. If you have a well laid out texture UV with no overlapping faces and enough padding you can use the Texture UV as well. This option was added in 4.5 to make it easier for those who didn’t know about 2nd UVs and didn’t understand what Lightmaps were when just starting out with the editor. The generated UVs has been there in some form since UE3/UDK. It was just refined a bit.

2. There are some caveats to using UVW Map. It can be used in to get your UV the way you like. This method will still produce overlapping UVs if you just apply a UV Map modifier. When you import just make sure the checkbox for “Generate Lightmap UVs” is set. This will take those projected faces that have been split apart and repack them. I tested this using a Cylinder, Box, and Sphere with good results. If you do not import with the option to generate lightmap UVs the mesh will have the “Invalid Lightmapping settings” material on the mesh.