ndickson

foam
Is it a representation of 0 to Last vertex? Instead of prim:vert index (if that's what it is) in the details view?

Correct… for pretty much any use case inside Houdini.

To clarify, you probably don't need to worry about this distinction, but the order of vertex indices may not correspond with the order of the primitives then the order of the vertices within the primitives. For example, if you do a Reverse SOP, the order of the vertices within the primitives change, but the vertex indices don't usually get changed. It's still 0 to the last vertex; the order may just not be consistent with the other order.

You can check this by putting down a grid, then adding an AttribWrangle on vertices, with “i@vertex_index = @vtxnum;” as the VEXpression. Open up the spreadsheet on vertex attributes, and vertex_index will show 0 to 323. If you put down a reverse in between the two SOPs, all of the same numbers will still be there; they'll just be in a different order, since the spreadsheet for vertices sorts by primitive, then by vertex order within a primitive.

Random trivia. :wink: