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I'm new to Blender and UE4, but my goal is to create a mesh in Unreal Engine that I can assign two different materials to. For example, I would unwrap three faces of a cube, assign that to the default UV map in Blender. Then create another UV map in Blender on that object and unwrap the other three faces and assign them to the second UV map I created.

Once this is done I would import the .fbx into UE4 and then be able to drag & drop two unique materials on to the cube mesh object, and each material in UE4 would only be assigned to 3 of the cube faces.

The problem I am facing is how do I "assign" the three unwrapped faces to a particular UV channel?

Is this the right way to do this?

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  • $\begingroup$ My answer on multiple UV maps may help you. $\endgroup$ – David Apr 21 '16 at 23:45
  • $\begingroup$ Thanks David. I'm not sure what I am doing wrong but when I change the active UV map from the UV Maps pane like you do in your example, the UV maps don't "stick". What I mean is, for example, if I unwrap 2 faces into the first channel, then click on the second channel and unwrap 4 faces, when I click back on the first channel I see the four faces, not the two I unwrapped. I'm not sure how to "save" the unwrapped mesh into that slot. I thought it would stick when the unwrap procedure was executed but it doesn't. Using v2.77. $\endgroup$ – Richy Apr 22 '16 at 2:36
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OK so my original assumption was incorrect. I was trying to set the mesh up so I could apply two (or more) different materials to the static mesh in UE4. I thought that I would need to create two UV maps and then somehow use those in UE4, but the answer is much simpler:

  1. Go to Edit mode for your object in Blender
  2. Unwrap the mesh
  3. Add additional material slots using the '+' button
  4. Highlight the faces on your mesh that you want assigned to this material channel and then click Assign

enter image description here

Do this for all faces in the mesh, assigning each face to a material slot.

  1. Export the fbx file and import into UE4.
  2. In UE4 you will see additional material slots allocated to your static mesh. You can then drag and drop materials from your UE4 library onto the mesh.

enter image description here

Additional tips:

  • I left the texture channels blank in Blender for each material slot as I was going to use materials (that already have textures assigned to them) that already resided in UE4. If you were to assign a texture to the material slot in Blender then that texture would be exported to UE4 inside the fbx file and appear alongside your mesh object in the Content Browser.

  • If a face appears missing on your mesh, it is likely that the face normal has been flipped during editing. Go back into edit mode in Blender, highlight the problem face, CTRL + F to bring up the Face menu, and Flip Normal. Re-export the fbx, right click the asset in UE4 and Re-import.

enter image description here

You can also display all face normals in edit mode by clicking Display Face Normals in the Mesh Display pane:

enter image description here

Hope this helps someone in the future.

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