ICE dynamic parenting

[Daysgone]

I currently am messing with setting up a dynamic parenting compound however I am having issues with the offset value between the child and the parent once. Currently its updating constantly and of course the child isnt following the parent. How would one go about locking the offset so that its only the inital value and not updated unless parent is switched?

[grahamef]

One way to approach this is to get the pseudo-parent's transform at the previous frame, calculate your offset from that, get the pseudo-parent's current transform, and re-apply your offset.

[Daysgone]

seems that get from prev frame only works if you have things keyframed not if your just moving the parent around.

[PhilTaylor]

In the constraints video, I show a dynamic parenting setup that works in the way Greyham described. Its towards the end of the video

http://webrel2.softimage.com/open/video/xsi7/01_Rigging_Constraints.flv

I have uploaded the scene file for you to look at.

The operator must be a simulation because dynamic parenting is history dependent.

You might have noticed that the parenting screws up when objects are selected, and this is a bit of a bug in XSI. I could work around it and upload it again if you want.

[Daysgone]

Thanks for the upload, it helps with a few questions that I had. It would be nice if playback wasnt needed, doesnt seem like it would be a good way to work in production, real time feedback would work better.

[grahamef]

Try setting the simulation environment's Play Mode to Live or Interactive.

[Daysgone]

ah good call with the simulation live or interactive.

Useing that given scene however it seems to be some sort of bug or feature. If I change the parent to any of the nulls, the child will not update on the first 2 frames of the timeline. If I move the timeline to frame 3 the child will move correctly interactively. I have also changed the start frame of the simulation to say -2 and it will not work interactivly till frame 0+.

EDIT:Ops same thing happens on the last frame of the scene, but first and last frame I expected it to not work like in the past with particles.

[PhilTaylor]

I'm not really sure what problem you are trying to solve. Setting the playback to Live means that the simulation updates during interaction, but that means that the results you get will be different when you play back the animation.

Are you trying to build and animation sequence, or just and interactive tool?

Depending on the desired result the solution might change.

Phil

[Daysgone]

Just an interactive dynamic parenting tool is all I was trying to accomplish. I have done it through scripting with turning on and off constraints and adjusting the offsets on the switch to have no jumping.