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ashmanmedia
ashmanmedia
Up and Coming
April 7, 2025
Solved

Backface Culling - 2 sided faces? Blender CMI texturing

What's the deal with backface culling in horizon? Example above the object the texture looks perfect FULL LEAVES under the tree the leaves look INVISIBLE?

Any tricks I've seen other places successfully accomplish this?

 

stormingdecker
stormingdeckerAnswer
Inspiring
April 7, 2025

I've had the same problem! It's listed in the docs that in Horizon that you can't disable backface culling. As recommended, I ended up duplicating the faces on the mesh that are mapped to the leaves material, and flipping the normals in Blender. That way it looks normal from both sides.

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6 replies

stormingdecker
stormingdeckerAnswer
Inspiring
April 7, 2025

I've had the same problem! It's listed in the docs that in Horizon that you can't disable backface culling. As recommended, I ended up duplicating the faces on the mesh that are mapped to the leaves material, and flipping the normals in Blender. That way it looks normal from both sides.

    ashmanmedia
    ashmanmediaAuthor
    Up and Coming
    April 7, 2025

    Thank you I was sorta afraid of that.
    Technically duplicating Faces is the same as duplicating vertex count or its doubling the object in this area? right? I'll definately adjust looks like decimate is my best friend soon. 😞

    TY AGAIN.

    stormingdecker
    stormingdecker
    Inspiring
    April 7, 2025

    Yes, it does double the face count for that area of geometry. More verts, more tris. You don't need to dupe the trunk though, so you're saving a bit there. Hopefully your foliage geometry is mostly flat faces with a masked alpha leafy texture. Then the render costs shouldn't be impacted too much.
    I also have to dig into the decimate modifier myself soon, I have dead dry trees in an area of my world that are a bit too dense in geo, and I feel the delay even when I duplicate them. 😅

    ashmanmedia
    ashmanmediaAuthor
    Up and Coming
    April 7, 2025

    so taking the leaves and duplicating just that of course flipping the normals opposite direction.
    do you dupe and leave same position or slightly lower so they for cause a MORE' affect?
    Again ty for your help always great feedback.

    FYI Decimate in Blender 4.4 seems to really shine and work alot better than previous versions.
    use like .25 .50 factor.

      stormingdecker
      stormingdecker
      Inspiring
      April 7, 2025

      I didn't end-up moving the leaves at all. Trying keep them in the exact same position, so it doesn't alter the tree from its original design / introduce edge gaps in places.
      Normally you wouldn't want to have overlapping tris like that when they are facing the same way, as it tends to introduces z-buffer fighting and visible glitching from floating point imprecision in the rasterizing pass. However, in this instance, the other backfacing tris get culled from the batch at rendering and don't get to write to the buffer at all, as if they didn't exist. So, no fighting, no glitching!

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