Objects with moving vertex - possible?

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Objects with moving vertex - possible?

Postby DiegoFloor » Mon Jan 05, 2009 10:09 pm

Hi there :D (tell me if I'm asking this in the wrong place!)

I would like to know how Newton deals with an objects that doesn't have static vertex. For example, a sphere rolling on the ground and every vertex starts to oscilates. Is this possible?

On a second idea, instead of moving vertex, I could make a model with bones moving. Would we still be able to apply physics dynamics to the mesh?

Thanks!
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Re: Objects with moving vertex - possible?

Postby DiegoFloor » Wed Jan 07, 2009 3:15 am

Now that I've read my question again, it's not very clear what I meant!

"a sphere rolling on the ground and every vertex starts to oscilates. Is this possible?"
I can make the sphere's vertex move! What I'm not sure is if Newton sees that.
Another example: I have a cube just sitting there... then I make a horn rapidly grow on the botton face of the cube! intuitively, the cube should gain some vertical speed. Is this simulated? Or the horn is just gonna penetrate the ground?

Thanks again!
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Re: Objects with moving vertex - possible?

Postby JoeWright » Wed Jan 07, 2009 7:05 am

Well no and yes. You couldn't do it by changing verticies. What you could do is have multiple bodies joined with hard constraints, then change the relative positioning in the joint (kinematic joint).

So, in your box horn example, you would have two objects, a box and a pyramid which were joined and fixed together in the contraint code. Initially the pyramid would be inside the box (with collision between the two objects switched off). Then in the joint code you would alter the reference points so the relative position changes smoothly and the pyramid starts to come out of the box.

I think a generalised system would need a non-rigid body simulation (Newton 3 I guess :D )

Joe
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Re: Objects with moving vertex - possible?

Postby JernejL » Wed Jan 07, 2009 8:08 am

I think what Joe is describing is a cloth / soft mesh functionality.
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Re: Objects with moving vertex - possible?

Postby DiegoFloor » Wed Jan 07, 2009 11:31 am

Ok! Thanks for the replies :D

This doesn't seem like a trivial task at all!
I was thinking a different solution. make the verticies move, but use a static collision model. So the movement of the verticies are for visual feedback... well, not only.. I was thinking about checking for collision with the verticies and the ground and apply a force on the object, depending on the intersection.
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