I am looking for a way to drive the transform components of multiple objects with a single CHOP network if possible. I am currently using a fetch node to gather input channels and an export node to direct the resultant output. The problem I'm running into is that the fetch and export nodes order the channel data differently. For example, setting up the fetch to bring in t r & z delivers the expected channels, ordered as expected: channels grouped by object first, then component. But the export node does not respect or maintain that order. Instead, export jumbles the channels, ordering by component instead of object. This is what the mapping looks like:

object01.tx –> object01.tx
object01.ty –> object02.tx
object01.tz –> object03.tx
object02.tx –> object01.ty
object02.ty –> object02.ty
object02.tz –> object03.ty
object03.tx –> object01.tz
object03.ty –> object02.tz
object03.tz –> object03.tz

To get around this I have created a single CHOP network to handle each component individually: There is a CHOP network for tx, one for ty, one for tz, etc. This is rather bulky and seems less efficient than using a single network. Is there a better way to do this?

Thanks,
-Judah

Not sure what you mean.

I routinely use one Chop network with many export nodes to different parameters in different objects; with a number of them that initially use Fetch and File for import purposes.

Maybe upload a hip file with a sticky to a specific issue.

Edit: I just remembered. Sometimes, because of the way I use chops - with a Fetch node I need to change the Fetch parameter drop down to “CHOP Data Channels” from the default “OP Control Channels”

Hi Judah,

Yes, this is a bit of a mismatch between the fetch and export CHOP nodes.

There are two methods that I can think of off the top of my head to get around this - one is to reorder the channels to match the order expected by the export chop using a Reorder CHOP, the other is to rename the channels and export directly from that rename CHOP (with the export flag).

When turning on the export flag of a given CHOP node, houdini uses the nodes ‘Export Prefix’ (under the Common tab) and the channel name to lookup the channel to override. By default the export prefix is set to “../..”, so a chop node with a channel named object1:tx will export to “../../object1:tx”.

Take a gander at the examples and see if it helps! Of course, in both our examples we are working with object names that are easily globbable (if that IS a real word ), if we want to generalise this to work with completely disparate object/channel names then we would probably be looking at a dive into VEX land.

Cheers,
Henry

Hi friedasparagus (is that is indeed your name - Henry),
This is just what I was looking for. It works exactly as expected.

By the way, on another topic, your instructional videos have been quite helpful. We are in the process of evaluating Houdini as a rigging alternative. I see some great potential, but I'm still not familiar enough with it to see the complete pipeline.

Today, just about anything can be considered a real word. I don't think “globbable” is much of a stretch, though it does offer some humor

Thanks again for the example file. Super helpful.

-Judah

Thanks friedasparagus….another possible way to apply chops I never considered.

Hi Judah

I seem to get away in a similar problem with just using the fetch chop as only node and use it's export itself, pointed to the receiving object or network.
Former methods are certainly worth noting for me but this is for the purpose the most elegant way, it seems.

Cheers
M