In the houdini doc about foreach sop it is said that.

“Houdini 12 introduced the Solver SOP. The Solver SOP is a much more straightforward solution for iteratively applying a SOP network to geometry.”

Cant realy figure out how to use the solver to iterate through groups, attribute values or primitives in a “procedural” way….

Any thoughts about what they meant by that ?

Thanks

Here is a quick exemple of what solver do.

Hope it will help you

the For Each SOP has 2 major behaviours
1. merge results of all iterations into single geometry (Merge Results ON)
2. feed back result from previous iteration to the next (Merge Results OFF)

and it is this 2nd behaviour that works similarly to Solver SOP

the main difference is the usage
if you want to iteratively modify the geometry over time by processing it with SOP network, it's more efficient to use Solver SOP since it will modify it only once each timestep
doing the same with For Each SOP would mean increasing the number of iterations every timestep by one, but that would need to recompute all iterations from scratch every timestep as well since it cannot access geometry from previous timestep, so the further it goes the slower it gets even if your geometry doesn't get heavier

if you however want to apply certain amount of iterations to your geometry at the current frame, like 10 smooth iterations or so, and possibly time independently if the input is not changing, then For Each SOP is the way to go, since it is doing just that

so no blind replacing For Each SOP by Solver SOP, it really depends case by case
and of course don't try to replicate For Each SOP's 1st behaviour with Solver SOP

Ihanks for your (very fast!) answer…

I actualy never thought I could use the foreach sop with the “Merge Results” OFF before reading your posts…

Cordialy