A while ago I was playing around a little in Houdini, encountered some problems and therefor abandoned the project. Now, that I recently found this project flying around here, I wanna go for a second attempt and discuss this problem now.

The idea was to build some sort of procedual tower, consisting of some boxes, and then having some rigid body hit that tower and make it collaps to its individual pieces.

The problem is, to seperate the boxes of the tower, I wanted to use a connectivitySOP, basically to group the boxes by their connected primitives. When I MMB over that connectivitySOP it says that indeed there is a primitive attribute called connected. But when I look in the geometry spreadsheet there is no attribute on primitive level or any other level. To make sure that it's not a bug of the connectivitySOP I, just for testing sake, created an attribute called box. Once again: MMB says the attribute is there, geometry spreadsheet says it isn't.

Where are my attributes and how do I use them to make this tower collaps properly?

a) The attributes show up for me just as expected. Remember that the spreadsheet is not a “global” view, it's always a view at one node's position in the graph. If you're looking at the Geometry Spreadsheet tab, then it always shows the state of the selected (yellow border) node. If you use the floating window via RMB on the node, then it always shows the state of that node.

b) You have created your physics object with the “RBD Object” shelf tool, which always creates just a single physics object. In this case you want to use the “RBD Fractured Object”, which can create a multitude of physics objects, partitioned by the primitive groups of your geometry.
To get groups from your “connected” primitive attribute, append a Partiotion SOP, with Rule set to $CONNECTED

eetu
…Remember that the spreadsheet is not a “global” view, it's always a view at one node's position in the graph. If you're looking at the Geometry Spreadsheet tab, then it always shows the state of the selected (yellow border) node…

I know I'm clicking on the nodes like crazy but no matter which node is active, it won't show the attributes.

Ah. The “pin” button means that the current view is “pinned” or “locked” to a single node, and does not follow the other panes. The node it seems to be pinned to is “subdivide1”.

Pinning can be quite useful, looking at the attributes of a different node that what you are editing, or e.g. looking at the 3d view of a different object (downstream in your process) than whose nodes you are editing at the moment.

Oh no! I didn't recognize it was pinned. Now it works
I guess the vexing thing about it is, when you see that there are attributes missing that should be there, one is likely to become some sort of nervous and then you you miss such obvious icons.
I had this problem for a long time. It seems that I saved my custom desktop with a pinned geometry spreadsheet.
Thanks a lot and sorry for the inconvenience.