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The thing I want is to carve out pieces of a mesh based on an alpha texture. It's not a noise texture, it's a specific alpha texture I have that is UV mapped, and I want to delete the parts of the mesh that would otherwise be transparent (in this case, because I want to use this mesh somewhere that can't handle transparency well or at all). I've tried to look around for an answer to this and pretty much all of them seem to be from before Blender 3.0, which used to have the Attribute Sample Texture geometry node. How do I do this in current versions of blender?

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You're always going to have sampling and topology issues with doing something like this, but understanding that, I'd do it something like this:

enter image description here

Starting with a plane, I subdivide it heavily, look up object coords on each face, and delete any where the alpha of my image texture is less than some threshold (here, 0.5.)

For mapping to something by UV, send UV as an input vector instead of position:

enter image description here

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  • $\begingroup$ That does not seem to work: imgur.com/a/v6w5wwe, no matter the threshold I pick or whether I pick Face or Point or anything else in Separate Geometry or how much I subdivide $\endgroup$
    – Red
    Feb 22 at 18:18
  • $\begingroup$ You're using UV. You should probably use UV rather than position for the lookup. $\endgroup$
    – Nathan
    Feb 22 at 18:20
  • $\begingroup$ How do I do that? I can't seem to find any primitives that map the texture by UV here but I may be overlooking it $\endgroup$
    – Red
    Feb 22 at 18:24
  • $\begingroup$ @Red Added an edit. $\endgroup$
    – Nathan
    Feb 22 at 18:39
  • $\begingroup$ Perfect, exactly what I wanted, thank you so much! $\endgroup$
    – Red
    Feb 22 at 18:47

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