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If I use generated noise texture to select some vertex, it's oK enter image description here But if image texture are used, all vertices will be select. Why?

Can I use the image texture to select vertices?

enter image description here

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  • $\begingroup$ Is your mesh UV unwrapped ? $\endgroup$
    – Gorgious
    Jul 21, 2022 at 11:24
  • $\begingroup$ You probably lost (or never had) UV coordinates. If you need reuse existing UV check here. If you don't have any you would have to position the texture like here ... by default a texture is placed with left-down corner at objects origin. $\endgroup$
    – vklidu
    Jul 21, 2022 at 11:41
  • $\begingroup$ Does this answer your question? Is it possible to Get UVMap Attribute from object info node? (Geometry Nodes) $\endgroup$
    – quellenform
    Jul 21, 2022 at 11:51
  • $\begingroup$ @vklidu, grid, that I use is generated by geonodes. It can't have uv $\endgroup$ Jul 21, 2022 at 12:08

3 Answers 3

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For you Mesh Primitive > Grid, Hulifier's answer seems to be the best.


UV Unwrap node

Since 3.3.0 Alpha, Geometry Nodes include an unwrap node that generates a new UV map, mainly used for newly created complex geometry by GN.

enter image description here

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do you mean like this?

enter image description here

enter image description here

Note: depending on your image (size) you may want to change the scale and add node values so that you can see "something".

Also it might be necessary to stretch the position values a bit so that the image won't get distorted (you can do this with a vector math multiply node)

..and of course you could use "more intelligent" ways to determine whether the instance should be shown or not than just compare alpha with greater than. You could e.g. take just the red value of the color value of the image texture...or whatever

unfortunately there is no "automated" way up to now to get the size of an image to adapt the size of the grid proportionally.

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The grid generated by Geometry Nodes comes with an UV attribute:

enter image description here

Knowing that, you can use it as input to the Image Texture node.

enter image description here

enter image description here

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  • $\begingroup$ +1 nice spot :) $\endgroup$
    – vklidu
    Jul 22, 2022 at 7:28

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