Hi there,
I'm working on an OTL which will process multiple assets with lop, but currently, I got a problem to read attribute value in sop( a sop modify lop in for each loop)

Basically I calculated some attributes based on input asset(saved on detail level), and I can see the result as a primvar when the loop end, but I can't read it as parameter inside sop modify.

Thanks,
Yuqing

This is an issue with the transient nature of context options set in the LOP network. The For Each LOP sets a context option, ITERATIONVALUE, which is used to cook each iteration of the second input. But if you just evaluate the nodes inside the for each loop, ITERATIONVALUE isn't being set. It's only set when cooking the For Each loop. This situation has been improved for the next major release of Houdini, in that LOP nodes will at least remember the last context option values used to cook the node. If the option isn't being explicitly set anywhere, the last-used value will be reused, making for more predictable, stable results when looking at nodes inside a for each loop. Though it is still not perfect, since only LOP nodes are made to use the “last used” context option values… When diving into the SOP Network, Houdini can still lose track of the context options used on the last cook…

Thank you Mark, that make sense to me.
I noticed that it is hard to debug when I using for loop in lop, especially for cross context actions like lop-sop-lop, for example I can't check the in-progress result, and also it will report errors when I cook nodes inside the for loop. I think they are all relate to the losing track of context options issue maybe?

Thanks again,
Yuqing

Yep, all the same problem.