Rope Belt Lag
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Hi Dr. Sassi,
I'm having an issue with the rope belt which I'm struggling to solve and I believe is down to a priorities issue.
I have this tent model which I am inflating with dynamics. I have four clips which are attached to the tent via Xpresso (it was easier and more stable to attach them that way rather than making them rigid bodies) and then the guy ropes are attached to the clips with the rope belt.
When I run the sim there is always a small gap (see screenshot).
If I cache the rope simulation and offset the resulting animation by 1 frame, the end of the rope lines up perfectly, hence why I think it's a priorities thing.
I've tried changing the priority numbers in the dynamics & rope tags, I tried the shift priorities tag and I've tried reording in the object manager evey which way but nothing seems to correct it.
I've seen that other people online have run into this issue. Is there a way to fix this?
TentSim_v20_Help.c4d Error
Many thanks,
Sam -
I'm not sure if that file .c4d I uploaded worked. Everytime I try to upload a file the website gives me an error. It's not very big only 1.4 MB.
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Hi Sam,
The max size is 1MB.
Please use Dropbox, Google, Adobe, Apple, or WeTransfer as cloud services. For security reasons, I will not touch others. Please upload the file not as zip nor as rar, no tiny URL, and paste the URL as is in the text, no HTML wrapper, etc. Sorry for the long text, but security comes first.
Have you cached it?
All the best
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Here is a Dropbox link: https://www.dropbox.com/t/HlPWgtATIwYLssMU
I've not cached it in this file, but I have tried caching it many times before. The problem still persists after caching.
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Hi Sam,
Thanks for the file and for using Dropbox.
What I did was set the Iterations to 2. No particular reason other than a gut feeling.
The next step was just to cache the tent itself. Nothing else. As the ropes react to the tent, that sets them, AFAIK, into a frame after mode. But caching the tent provides the needed information directly. (Yes, The Object Manager was organized correctly. You placed the priority to -400 instead of the 400 it has by default. ThisThis means that anything after -400 is calculated based on it, providing the Simulation with data from the frame before. Objects need to be generated before they can provide data. Here is a catch. The chain is a Simulation>object generating>reacting to that object>generating the robe.
From my point of view, that needs the initial sim object to be cached, preferably the last Simulation as well.
If that hadn't worked, I would have used the cached first object and converted it into an Alembic to utilize the time offset option here. But it worked without that.Then I went to the Ropes and cached those.
Let me know if that works for you. Otherwise, I provide you with the link to the solution I have here; it is a bit large due to the cache.
Enjoy your weekend.
