In the Resource Tree pic below, can anyone tell me which lines refer to the object itself (mesh, texture etc.) and which ones refer to the actions you can take with the object?

Technically, if I wanted to make the interactions apply to a different object would it work to just replace all the object resource lines with the other object's?

TL;DR:
1) It's a bit more complicated than that....
2) More often than not, no.

Trying to separate function from form isn't a black-and-white issue. It may not be too unlike asking "Which part relates strictly to a bird: the beak, wings, singing, or the feathers?" Different resources in the package file structure are interwoven together....some components house critical information for both what constitutes the "visual" aspects of an object and its in-game "functional" aspects. Some objects change appearance dynamically or through interactions on the object.

You might check out An overview over the Package structure and Package Resource Graph for a look how different components are linked.

It also depends upon what you mean by "interactions" and what you are trying to do...

If you are trying to add an interaction in which you click on the object and then tell a Sim to do something, you would approach adding the interaction from a particular angle and make use of certain resources in the .package file structure.
If you are trying to add an interaction in the sense of a behavior (e.g. the pond lilies and kitchen counters alternate meshes when bought or placed), then you would likely approach adding that type of interaction from a different angle and make use of different resources.

If you are trying to make one object look like one object but function as another (e.g. make a lamp that looks like a chair), then you would go about that a totally different way. You'd clone the lamp and make a temporary clone of the chair. You'd extract the meshes and textures (not the GMDC and TXTR resources themselves) and import them into the lamp, making whatever adjustments to the MMAT(s) would be necessary....


Since this is the Object Workshop, perhaps you could post what you've done so far?

Thanks, but I ended up deciding to start from the beginning with the object instead.