What is the importance of Apex's use of point containers for nodes? Or, why is it useful that moving, adding or deleting the point geometry also moves, adds or deletes the corresponding node?

It is a pretty slick feature but I'm not really sure what to do with it. Is it that graph parity with the node network makes it easier to understand? Or is it a bigger idea down the road, that parameters will be adjusted in Python states so most work is done in the viewport, node parameters being updated in sync?

It's worth reading this a few times, I keep reading it, and will continue to read it until it sinks in.

https://www.sidefx.com/docs/houdini/character/kinefx/apexgraphs.html [www.sidefx.com]

I'm not an expert in APEX by any stretch. But I've started trying to duplicate my rigs from other programs starting with 20.5. My short answer is that there's no immediate point to it from a user standpoint (or at least I haven't seen one). You're not really going to be moving around the rig graph, unless you want to make fun animated graphs to show off to your friends.

However, what's interesting is that SideFX found a way to treat the process of rigging in a way that is very similar to the way it treats everything else in SOPs: as the manipulation of points, prims, and vertices which all carry various attributes around.

The biggest ah-ha moment for me was beginning to realize that I can store all kinds of important information about the way a rig should behave on the skeleton for that character instead of within the rig itself. Then I can create a series of modular rigging components that read those attributes and can update their behavior based on them.

To me that's kind of mind-blowing. It means that a much larger percentage of a base rig can be set and re-used again and again and again across multiple characters, with a much smaller percentage of the rig needing to be customized for each character. And that within that base rig I can generate a much wider range of behaviors from the same rig, only by changing the attributes I pipe into the rig.

There’s no reason to move the nodes or points really, it’s all about sticking with the Houdini ecosystem. Since we’re working with points, it basically means we can do whatever we want, add any attribute we want, create any Component we can think of and keep it modular. We can even save out the entire rig (skeleton, geometry, control rig, constraints) as a single piece of geometry.

APEX being fully homogenous with Houdini’s methods of point manipulation basically makes this system endlessly extendable, and that includes updating your rig directly in the viewport within viewer states.

Michael Goldfarb says the same, (paraphrasing) "there's no point to storing rig attributes as points except that Houdini is especially good at manipulating points, etc.

I haven't used APEX a lot but I see your point. He feeds the same rig set up into several characters and the tags handle the different topos. Pretty nifty stuff.

yes, I did say that didn't I?

we could have invented some sort of custom format to store the rig, but the skeletal geometry is right there so why not
it's just a quirk that you can then load this geometry and view it - makes for some fun tricks!