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Where do these Ops go?

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Sorry for the ambiguous title, but I'm not sure what an appropriate one would be. Hopefully reading my issue will clear it up.

I've created a stony building under the effect of gravity and a ground plane, but am having issues with how to constrain the pieces of the building so they don't immediately collapse when the sim begins. There's a cannonball that's supposed to do its thing first... then gravity, etc.. 

In some tutorials, the dops is created inside the sops network (where my building is constructed). In others, it's at the obj level. I've tried using both methods but can't get the constraints and the all the other dops stuff to work together. I'm typically left with only one or none of them working.

I've heard that dops and sops can be put together at will, but this isn't what I'm experiencing. Can someone provide a clearer rule of how/where these operators are supposed to be constructed? For instance, if I create all the geo for the building, should the cannonball be constructed in that same node, or should it reside on the obj level next to the building node... or maybe inside the dop itself? Just wondering since the dop calls geo via an rbdpackedobject node, so can't the dopnetwork node be inside the building or even the obj level...?? If so, where is the constraint node made?

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There is no clear rule how to construct your scene. It's up to you how you want to structureit. In the end all you pass to the dopnetwork (and other nodes) is references (=> paths) to a node somewhere in the scene.

You might want to structure your scene in kinda logical steps. For a destruction scene that might be one object level node called prep_geo where you load in your alembic of the house or whatever and prepare it for fracturing.
Next might be a object level node fracture_geo where you do all the fracturing.

Now here it really starts to come down to personal preference. You could create a new node constraints where you build the constraint network and then a dopnet at object level.
Or you do all that inside the fracture_geo (which you then might wanna name differently). 
That's what I like to do because constraints depend on your fracturing so if that changes I don't want to dive in and out of nodes all the time to switch from fracture to constraints, etc. 
Also, although I tend to not use them, I like the inputs on the dopnet as quick way to feed it data. On object level they are useless.

Everything that comes after the main sim (debris/dust/instancing hiRes pieces/etc) is also totally up to you how to structure it.
Sometimes I can't be bothered and I do everything in 1 node :ph34r:

TLDR - for your constraints to work it doesnt matter where you put stuff, you just need to check that all references/paths are correct. Also if working with object level nodes make sure transforms are zeroed out (or take extra care when object merging things)

Edited by 3dome

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Danke 3Dome. Much of what you're saying is what I thought in the beginning, but my results vary so much that I'm not getting good sense of how this should work.

So, just in case you (or anyone else) cares to take a peek, my latest attempt is attached as a hip file.

Goal: It's an elementary attempt to destroy a castle tower with a cannonball.

Result: It's a mess though. The ball simply passes through the tower without affect and its anim only plays at the obj level. I've tried including it in different ways, but all my attempts have proven fruitless.


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