Hi,

Quick one here
I have some geometry with many primitive groups. I'd like to create an attribulte “groupid” which will store an index of the group. Say I have 10 groups, so the attribute would be 0 on group1, 1 on group2 etc…

Which node should I use? Attribute Wrangle? But how?

Cheers,
B.

Here you go.

Thanks! That's so simple… but one tricky thing is i have over 100 of those primitive groups
Probably should just iterate in vex, should I?

Cheers,
B.

Hi B,

you can use the ‘Name SOP’ to create a primitive attribute from groups. You can do any iterations you wanted using that attribute in for-loops etc… so you may well be able to stop there.

Or if you really want an integer attribute you can look up the index of that new ‘name’ attribute in the “primitivegroups” detail intrinsic attribute (see the attached file). Bear in mind that the ordering of groups is not very easy to keep track of or control if you need to change any groupings upstream, so your integer attribute may not behave as you might expect, depending what you want to do with it.

Hope that helps,
Henry

Ok..so I changed it to accomodate large number of groups.

Mind you, this only works if the prims only ever belong to one group,

otherwise they get the last group checked as the indice of the group the prim belongs too.

Of course it's only a minor change to the code if you intend to have a prim/s belong to more than one group.

Thanks guys!
I just thought hashing the name attribute will give me a consistent id based on the group name, and that's actually enough of what i need, coz I don't need to go back from the indices to the groups. I need it to help cluster some geometry.

Thanks again!
B.

BabaJ
Ok..so I changed it to accomodate large number of groups.

Mind you, this only works if the prims only ever belong to one group,

otherwise they get the last group checked as the indice of the group the prim belongs too.

Of course it's only a minor change to the code if you intend to have a prim/s belong to more than one group.

This just helped me out! Thanks for posting the file. Really appreciated