Thanks guys, I already tried applying thickness, which does indeed help to eliminate the
offsets for both Bullet and standard Rigid Body Collision nodes, but the strange
"ghost" collisions in some places stay when using the Bullet one. Btw, this
also happens in 2012, I'm a bit surprised seemingly nobody ever noticed and reported
this. Nobody using ICE to do RBD these days?
Cheers,
Stefan
Here is one guess - try making a solid bowl rather than single width polygon
sides - i.e. take a cube, select the top poly CTRL -D it scale it in - CTRL D
that and move it down - I am guessing like the normal RBDs which hate colliding
with a grid but find a cube floor much better.
Do I make sense?
S.
_____________________________
Sandy Sutherland
Technical Supervisor
[email protected]
_____________________________
________________________________________
From: [email protected]
[[email protected]] on behalf of Stefan Kubicek
[[email protected]]
Sent: 02 August 2012 18:25
To: [email protected]
Subject: Simulate RBD and Simulate Bullet RBD issues
Hi all,
I'm having problems getting accurate collisions using Simulate Rigid Bodies and
Simulate Bullet Rigid Bodies nodes when trying to fill a box mesh with
spherical particles, namely:
With simulate Bullet Rigid Bodies I get collisions in areas that are not
occupied by any collision geometry.
That is: collisions occur even though there is no collision geometry to collide
with. See attached SI2013_Simulate_Bullet_Rigid_Bodies_Ghost_Collisions.jpg
please.
This happens independent of the collision precision. The geo is sane and there is nothing
hidden either, I simply created a cube with some subdivs and removed the top polys so
particles can fall in. Of course, I had to set "Exact Shape" for the collision,
otherwise the particles would not even fall in but collide with the convex hull.
The only remedy I found so far was to cut the box up into pieces for each of the walls and floor,
and having particles collide with that. While this results at least in no "ghost"
collisions, I still get a collision offset between particles and the collision geo, whic is also
true when using the non-Bullet "Simulate Rigid Bodies" node, see
SI2013_Simulate_Rigid_Bodies_Collision_Offset.jpg please.
Ultimately, I guess I have two questions:
1.) How do I get accurate collisions with Concave meshes using Simulate Bullet
Rigid Bodies without having to cut the geometry up?
2.) How do I avoid gaps between particles and collision geometry? I could not
find any parameter controlling it. I must be overlooking something, otherwise
it would be pretty useless.
I know, there is Momentum, but one would assume the ootb tools, since they are
there, are good enough for such basic stuff.
Thanks a lot,
Stefan
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Stefan Kubicek Co-founder
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keyvis digital imagery
Wehrgasse 9 - Grüner Hof
1050 Vienna Austria
Phone: +43/699/12614231
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Stefan Kubicek Co-founder
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keyvis digital imagery
Wehrgasse 9 - Grüner Hof
1050 Vienna Austria
Phone: +43/699/12614231
--- www.keyvis.at [email protected] ---
-- This email and its attachments are
--confidential and for the recipient only--
