Is it possible to have a subnet of geometry that you can then copy or instance over some larger geometry container? For example, say your modeling a spaceship, and you have a subnet that represents a gun turret. The subnet has various geo containers, parented up for more convenient animation later on. Now you want to take this master turret and scale it down and copy it around the main ship. The Instance object seems to only want to work with geo containers, NOT subnets.

The other way is to just have a single geo container and have all the pieces inside it. However I was under the impression that this was not the preferred way to model, especially if you might want to animate later on.

jimc
The Instance object seems to only want to work with geo containers, NOT subnets.

Yes, you can't instance Object subnets, or procedurally copy Objects for that matter.

The other way is to just have a single geo container and have all the pieces inside it. However I was under the impression that this was not the preferred way to model, especially if you might want to animate later on.

I think you have to think about the trade offs between instancing, copying, and animating. Generally, when you instance, then it's much harder to individually animate the copies. So I think that you're probably down to making copies of the geometry. At least, all those copies that you wish to have animated. Since you cannot procedurally copy Objects, I think you're down to generating copies at the SOP (aka geometry) level. If you have lots of gun turrets, then I'd imagine that you don't want to be hand animating them all anyhow. So in practice, you'd want a mix of the three.

It would be cool if you came up with a system that while generating the gun turret copies at the SOP (aka geometry) level, it still lets you arbitrarily choose a gun turret to hand animate. I'm imagining something along the lines of copy/stamping the gun turrets to your ship. Then to drive the animation of the turrets, you have some Object-level HDA that you put down and specify the turret to animate. This HDA uses an internal CHOP network to drive the actual turret animation done via the copy/stamping. This might make a good effects challenge over at odforce.

edward

jimc
The Instance object seems to only want to work with geo containers, NOT subnets.

Yes, you can't instance Object subnets, or procedurally copy Objects for that matter.

Err…. sure you can? Well not with the Copy SOP, but with Mantra you can.

All the cannons are positioned with an Instance Object.

Wolfwood
Err…. sure you can? Well not with the Copy SOP, but with Mantra you can.

I stand corrected. Love your pic btw

edward
I stand corrected. Love your pic btw

Yea its pretty neat now, since you can instance subnets, you can instance things like light collections with geometry and what not.

Wolfwood
Err…. sure you can? Well not with the Copy SOP, but with Mantra you can.

Wow! That's really cool. Thanks alot for doing that! My only question, and maybe I just need to study the file a bit more, but where is the actual connection made between the points that you generate and the instanced geometry? Anyhow, really good, I'll look at this some more.

jimc

Wolfwood
Err…. sure you can? Well not with the Copy SOP, but with Mantra you can.

Wow! That's really cool. Thanks alot for doing that! My only question, and maybe I just need to study the file a bit more, but where is the actual connection made between the points that you generate and the instanced geometry? Anyhow, really good, I'll look at this some more.

The connection is made with the Cannon_instances node. Its an Instance Object which makes setting up point instancing a bit simpler.

This looks super useful. Could we get an updated hip file? The current one doesn't work in Houdini 18.
Thanks!