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xsitar
03-26-2008, 12:38 AM
Hi

I have an emdl model file that contains two meshes parented to the model null. These two meshes represent one object but are two parts.

Now i need to run a rigid body simulation and that model needs to behave as one when it hits the passive rigid object. But unfortunately when i branch-select the model and apply rigids it only applies it to the null and therefore doesn't work. The null simply passes through the passive object.

When i select both meshes only they unfortunately go apart when they hit the passive object but should remain still as one.

I tried the merge or blend mode to just have one single mesh but unfortunately it gives me a lot of errors and the meshes get screwed up.

Is there no way to apply rigid body dynamics on null models with containing meshes that act as one if branch-selected-and-applied?

Chinny
03-26-2008, 01:21 AM
Parent one mesh (MeshA) under the other (MeshB) - ignore the model null

Make MeshA Passive and MeshB Active

They will now act as one object.

or

You can make them both active and use a rigid constraint, then animative its activeness

Chin

xsitar
03-26-2008, 01:28 AM
thanks.

are you saying that mesh-a and mesh-b will act as one when they hit mesh-c?

just to avoid confusion. because mesh-a & mesh-b are one to hit mesh-c (not mesh-a hitting mesh-b).

Chinny
03-26-2008, 01:32 AM
thanks.

are you saying that mesh-a and mesh-b will act as one when they hit mesh-c?

just to avoid confusion. because mesh-a & mesh-b are one to hit mesh-c (not mesh-a hitting mesh-b).


Correct they act as one object when hitting MeshC

xsitar
03-26-2008, 02:23 AM
i have some problems making it work.

i did what you said but the mesh under the parent just blows up. are you sure you didn't mean mesh-c when you said "make it passive"?

i put mesh-b under mesh-a. i made mesh-a the parent and the active rigid while mesh-b is the passive.

then i made mesh-c to be the passive one so they collide and applied a gravity force to mesh-a.

unfortunately mesh-b just fly's off the screen, respectively blows up to a big size.


the closest i could make it work is this way:

i put mesh-b under mesh-a and then i branch-selected mesh-a and made it active rigid while mesh-c is passive. mesh-c didn't respond however when "actual shape" selected but only with bounding box set. the collision was also pretty damp and there was no bouncing at all.

hmm. i hope you could give me some more suggestions if possible.

many thanks

Chinny
03-26-2008, 02:51 AM
What XSI version are you running? Compound shapes do not work in 5.11, so you would have to use an RBD rigid constraint (which you might want to try anyway)

Also check your collision shapes and that the meshes to not overlap a lot

Chin

xsitar
03-26-2008, 03:47 AM
6.5

did you suggest to use compound shapes? sorry i'm not a super expert with rigid body dynamics.

is there a way you could outline the process specifically in case it differs from what you already explained? thanks so much.

Chinny
03-26-2008, 12:26 PM
Sorry my bad, compound shapes means parenting passive objects to active ones (as we discussed already)

I would suggest you try using Create>Rigid Body>Rigid Constraint>Fixed and animate its activeness

Usage, Select MeshA then add select MeshB - then do Create>Rigid Body>Rigid Constraint>Fixed

Chin

xsitar
03-26-2008, 04:03 PM
I'm not sure if it's because of how the model properties are or what but none of this works. I tried many different ways. Even when i merged the meshes as one i don't get desired results.

I never had this issue. But now even as one object it doesn't behave the way it should. I made a simple setup which always works usually but now the object just passes through the other one.

I guess i have to just keep on trying. Thanks anyway for your time.

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