I have a sim of a character on the edge of a cliff, at key moments parts of the cliff crumble. So my sim includes a static part of the cliff, larger chunks to fall off and small slivers of rock.

the static cliff is a non active bullet object. all the rest of the chunks are active and glue adjesent is used to hold it all together. All objects are packed rbd objects. I am dissolving the glue in the sops constraint network like one of the examples that come with the h13 bullet masterclass video.

On the first frame all the parts of the sim jump down, a small distance and then the sim behaves as you would expect from there.

I set up a super simple example to show it happening. in the example file it moves much less but shows the problem. in my scene it is moving about 5 cm relive to the character.

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Attachments coming out of our office are a non trivial event. He said siting at the only work station that you are able to attach files on.

By activating gravity a few frames in - it appears to be fixed.

thanks. my solution was to make the cliff dynamic and have a big slab of concrete attached to it and then sit that on top of another slab of static concrete.

interesting! it looks like a bug, doesn´t it? I mean, if you activate Gravity from frame 2 onwards as Marty suggested it doesn´t act that way…

PS: why is this at the SI users forum? Robert, were you simulating this on Softimage?

Guess i was wondering why the hell there is a softimage forum reading the posts then added the post, I didn't pay attention when I added the topic.

I tried the gravity on frame 2 trick and went back to the big concrete slab trick.i must have some inter penetration and this force to fix this on the first frame is moving the geometry without the need for gravity. So being attached to a 25 tone slab, and stiiting on another slab fixes that.

Just read a post where Bullet mass is calculated on the first frame step - ie. 1 to 2. That might be it?