Editing, or at least accessing, footprint primitives.

[alexA3RDM]

Say I've got a footprint with a bunch of primitives in it. In other CAD packages, I can edit that footprint live on my layout. Obviously that'd messy and non-ideal, but for certain small changes, it's less-messy than making a bunch of variant footprints. For instance: I've got a Raspberry Pi footprint, but I only need a few of the pins on its header, and want to delete all the others to free up some valuable SMD board area.

I'd like to be able to delete through-holes on the board, rather than making a bunch of project-specific variants of the footprint with pins removed.

Even if you think this is silly and I should just do that, I'd at least like to be able to ACCESS footprint primitives. Since Eagle has no concept of snap-to-object-hotspot or anything like that, positioning things is completely left to manual math on (x, y) coordinates. I hate that, but it's besides the point here. My real point is, if I want to line an object up on, say, pin 1 of a footprint, I can't simply look at pin 1's coordinates in my layout. I have to get the component coordinates, open the footprint separately in the library editor, and do a second layer of coordinate transform math.

This is really, really godawful. Let me at least "info" footprint primitives. 

Is there some other way that the rest of you solve these problems?

[didrik.madheden]

One hack for figuring out the exact position of a pad is to route a straight track from the pad, then look at its X or Y position (whichever is appropriate for the orientation of the part) and use that to position the other part. Then,  knowing the pin pitch which is presumably a standard value like 0.1" (100 mil) or 1 mm, you could place the other parts. I do believe that parts which are automatically placed when creating a component in the schematic will always be placed on the set grid at the time of creation, which should simplify the layout somewhat. You could for example first place the part roughly in order, at the grid pitch, and then select and move them while holding alt to activate the alt (fine) grid setting to finalize the position of the group. 

What would be useful though (feature request!) is the ability to use the pattern tool in the schematic, either for new or existing components, while keeping schematic back annotation.

As for editing primitives, this is not currently possible, but I don't think it would be impossible to add, as the document already contains a full copy of each part in the design, which can even be exported with a ULP. It would not be much of a stretch to have the ability to edit this copy locally in only the current document.

[alexA3RDM]

That's exactly the kind of hack I wish we didn't need, but that I was hoping someone would have! Unfortunately, yeah, not that useful for getting coords of non-pad objects (like, the top/left/right/bottom extent of a component from keepout or silk).

Interesting point about editing - I hadn't even thought of that, but it does seem like it shouldn't be a huge stretch to allow for local modifications to any given component, since they're library-linked, but not stored there. Seems like it shouldn't be too big a deal to enable a quick check during library updates for "this part has local modifications, update anyway?"