Backface Culling Fixed + Explained

So here is my first tutorial! Today I'm going to talk about Backface Culling and Normals and how to deal with them when you're meshing with Blender and Marvelous Designer included. 

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Backface Culling

Have you ever finished meshing something in blender and felt it ready to be imported into Sims4Studio? And when you do, is part of the mesh invisible?  I remember when I was just getting started, I nearly pulled my hair our trying to find what caused this. When you make a new mesh, its vertices are only made up of single faces which are automatically facing the front. 

By default, Blender shows the mesh as if it has faces on both the front and back which is why it might look okay…in Blender. However, in Sims 4 Studio, only the front of the mesh is visible and the inside of is just a blank void. To resolve this, there are a few solutions and I’ll go over them.

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Solution 1 - Closing Gaps

Things to note: This method is used on simpler meshes like shirt, shorts, etc…

Depending on the kind of mesh you make, this is the most common one as it hides part of the Sim’s body that you’ve deleted that would be visible otherwise.
 

1. Select the edge of your mesh, and press ‘E’ to extrude region or the ‘Extrude Region’ button in the ‘Tools’ menu

2. Press ‘S’ to scale the extruded part of the mesh inside until it’s closed to your liking

3. Finally, import the mesh into Sims 4 Studio

Note: Since the mesh I’ve made has ruffles, this wouldn’t work without it looking extremely odd.

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Solution 2 – Flipping Normals (In Marvelous Designer)

Things to note: This method is used when the front of your mesh is visible but the back isn’t.

Firstly, normal are used in game for Backface Culling. They tell the game what it should render/show and what it should not which is an aspect of what helps it run smoothly while you play. Also, why parts of your mesh are invisible. It’s all about optimization.

With normals you can fix them in both Blender and Marvelous Designer. How you can tell if the normals are flipped ‘round is when part of the mesh is white while the other is a dark grey.

4. Click that grey mesh and right click. On the list you’ll see an option that says ‘Flip Normal’. Click that and the mesh will turn white meaning that it’s now on the right side. You can import it to Blender!

Note: This is also possible in blender but that will be shown in the next solution.

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Solution 3 – Duplicate the Mesh

Things to note: This last method is better for meshes with lots of curves that extruding the edges of the mesh won’t conform to and/or if you want parts of the sim’s body visible.

Make sure that you’ve already arranged your UV maps before duping the mesh.

!!!Important!!! This is prefect for the more complicated meshes however if you do choose to use this method, you will end up with a high tri, face & poly count. You might have to decimate your mesh (or again if you have already). You’ll risk losing a little bit of detail to your mesh.

1. Left click on your MD mesh and hit ‘Control + C’ to copy the mesh. Then paste it using ‘Control + P’. It will paste in the exact same spot as the original mesh so don’t worry about moving it around.

2. Click the Original mesh and enter edit mode, press ‘A’ to select all of the mesh then press the ‘Spacebar’ to bring up the search feature. In the box type ‘flip’ then on the list, choose ‘Flip Normals’.

Note: After you’ve flipped the normals, it will turn a dark grey showing that the mesh is inside out now.

3. Click the duplicated mesh first (the one that doesn’t have its normals flipped) then click the original mesh (the one with the normals flipped)

4. After that, go down to the ‘Object’ menu and click ‘Join’ Or alternatively, use ‘Control + J’ When you join the meshes together, they will turn white. Now the mesh’s faces have a front and back.

Note: Now when you enable Backface Culling, the mesh won't be invisible anymore!

5. Finally import it into Sims 4 Studio and see the changes

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Hopefully this helps, if you have any questions please do let me know. Either here or on Lovers Lab, I will try my best to answer them!