Xgroup question

[Srek]

I think you understand best if you simply select a node within a setup (with connections on both sides), right click on it and choose "Convert to Xgroup" You will immediately see how it works.
Cheers
Björn

[ThePriest]

So, the full size - non-collapsible xgroup that is default, would have very little usage?
I mean I've never seen it used.

[Srek]

Ah, you are talking about the left and right border of the Xpresso node editor that looks like a Xgroup.
Inputs on the left are available like user data fields on the Xpresso tag, the ports on the right are currently not used.
Cheers
Björn

[ThePriest]

I figured there was no place they could go. Thanks for clearing that up Srek.

[mazab]

It would be cool if the output ports of "big" XGroups (of a whole XPresso tag) could be available as global variables. So if you output "custom value (Integer)" at one XPresso tag you'll get "custom value (Integer)" as an input you can add at all other Xpresso Tags.

[rui_mac]

Excellent idea. That would be great. But I do believe that it would have an issue with the evaluation order. The Xpresso expression that would create a specific Global variable would need to be evaluated before that Global variable was used in other Xpresso expression. That would require some re-ordering in the Object Manager or too much priority fiddling and that, sometimes, is not possible/wanted.

Rui Batista

[mazab]

With all more complex rig priorities are an issue. There's the priority setting in each tag where you can set your own execution order so a fix for priority issues is already implemented.

Whenenver you use more than on XPresso tag you need to take care of priorities. For example if you decide to build your own camera rig and use more than one Tag for it (for whatever reasons - convenience for example) you need to make sure to set the position of the camera before you have it looking at the target.

[rui_mac]

I know all that about priorities, Mazab. But with Global variables I believe things can be a bit harder. Because when we are programming in COFFEE or C++ (or any computer language that allows globs variables), the global variables are defined and they ALWAYS exist, even if they are not initialized with a value. That is because compiled languages (or even interpreted ones) have a prepass process that reads all variables beforehand. There is no prepass in a Cinema4D file. If an expression would try to use a Global variable before it is created, unpredictable results could occur. This can be fixed with the setting of priorities but errors can occur before people try to deal with priorities.

Rui Batista

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