Geometry nodes "Decimate"?

Support Animation and Rigging
1

Has anyone made a geometry node set-up that reproduces the effect of the Decimate modifier ?
And if so is there a major performance difference ?

2

Probably not the answer you were looking for, but you can apply a decimate modifier on the original object you are instancing and the changes will reflect back onto them.

1 Like
3

Not quite the same:

image
image2398×1597 383 KB

(One would have to look into the code of the decimate operation for an accurate replication)
poor_mans_decimate.blend (123.3 KB)

4 Likes
4

@LordoftheFleas Thanks! We’re getting somewhere. I think the main differences that make the Decimate modifier better so far are that :

  • it doesn’t just delete geometry but rather places new but fewer points on the surface. If you decimate a mesh, you may notice vertices appear where there were none in the original mesh, seemingly at edge midpoints.
  • it seems to prioritize decimation of low curvature areas, leaving the more curvy parts less affected
  • it doesn’t merge islands

All these factors help drastically to preserve the shape of the object better.

I’m sure we can improve this node setup, perhaps using the edge angle node for the low curvature part?

5

@RPaladin My situation is a little more complex so I’d like to have it as a node group.

6

So this is the code…
a bit more involved than what I posted :sweat_smile:

7

Thanks. I don’t know C though so right now I’ll either try to improve the node setup by comparing visually and fiddling with nodes or just keep using the modifier.

8

did you find a solution to this problem? I’m also trying to use a decimate node group in geo nodes

9

Nope, sorry. Still using the modifier.

10

I need decimate modifier too. I hope it will appear in future in GN.