Objects sink through the floor

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Jun 28, 2009, 1:38:33 PM6/28/09
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Hello! I have a static floor which consists in a horizontal plane tied
to no dynamic body (or, to 0). Unfortunately, it looks like the
objects that should be standing on the floor tend to sink through it.
Or in other words, the force applied by the contact joint is not
strong enough to keep them in place. Here are a few tests that I made:
* VERY heavy objects sink very fast; very light objects still sink
reasonably fast.
* An INCREDIBLY small CFM makes the objects sink slowly, but they
still sink.
Tried with ERP 0.6 and 0.8 .
The stepping function is dWorldQuickStep with 50 iterations.
This issue affects small objects that are normally not moving (so only
gravity is affecting them), but which must be dynamic so the players
can go and push them around.
Any suggestions? This must be a fairly common newbie issue, but a
search didn't really return any solution for this problem...

Daniel K. O.

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Jun 28, 2009, 2:23:53 PM6/28/09
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Protected escreveu:

> This issue affects small objects that are normally not moving (so only
> gravity is affecting them), but which must be dynamic so the players
> can go and push them around.
> Any suggestions? This must be a fairly common newbie issue, but a
> search didn't really return any solution for this problem...

First try reproducing the problem in one of the demos, like boxstack.

Then search the group for "sink", you'll find comments regarding the max
correcting vel, variable timesteps, huge timesteps, wrong collision
data, etc.

If you still can't figure out where the problem is, post your code
somewhere like pastebin.com so we can have a look at it.

--
Daniel K. O.
"The only way to succeed is to build success yourself"

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Jun 28, 2009, 2:33:40 PM6/28/09
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I had already searched. I had none of those problems you mentioned!

I seem to have solved the problem by enabling dContactApprox1 in the
contact joints. I don't know why this works though!
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