Do Shadow Maps Have Material IDs?

Hello everyone,

Just a quick question: Does Unreal 4 generate a shadow map for every Material ID a static mesh has? For instance, a mesh with 12 Material ID’s would have 12 channels for textures and 12 channels for lightmaps, totaling 24 channels?

I’m working with a model that has 12 Material IDs right now. I have unwrapped some of the channels but haven’t got to others yet. I specifically unwrapped channel 12 and gave it a second UV channel to hold the lightmap. I double checked to make sure nothing else was on it but I’m getting what looks like a lightmapping issue. It’s the issue where the texture is dark and doesn’t light properly yet I know that my elements on channel 12 have a UV channel 2 that doesn’t overlap. That’s what made me wonder if there is more on my Material 12 lightmap than I thought.


Your lightmap applies to the entire mesh regardless of material ID.
Also, each UV channel and Material ID you add increases draw calls, so don’t use more than is really necessary.


Ah I see. I may have to do a little rethinking then. Thanks for your help!