Small Objects reacting weird?

Hello everyone.

I was trying to create a game that uses small objects, i mean really small, like Spheres with Radius 1.75cm (yep, centimeters). and i notice that they didn't react very well.

I have a Triangle Mesh (lets say a Box (100cm x 60cm x 15cm) with the upper face Open) and i "drop" a ball inside it, and i notice that the ball never stops "bouncing". And this didn't happens when i use larger Boxes and Balls.

Any idea why this is happening? Are the Objects to small? If this is the case, should i "scale" everything?

Like, change gravity to -98.0f Instead of -9.8f, multiply the Value of the Mass, etc?

Thanks in advance

Well, I guess scaling could be one solution, but I am also pretty sure, that there are some parameters that affect the bouncing behaviour.

I can only make vague guesses (perhaps having a look at the PhysX documentation can help, to find out what the correct terms are for these values as they will be the same in NxOgre):
- damping coefficients in NxOgre::Actor
- sleep threshold also in NxOgre::Actor
- skind width in NxOgre::Shape

Did you also have a look at the RemoteDebugger, to make sure that the scene is fine (so that this ball e.g. isn't entering the box due to Non-CCD issues or similar)?

Hello, thanks for your reply.

Seems that the problem is the Non-CCD.

Since its not yet implemented in NxOgre, i'm trying to add it manually. But i'm getting a few questions.

For instance, in the example of CCD of PhysX they have this code:


...
// The actor has one shape, a box
NxBoxShapeDesc boxDesc;
boxDesc.dimensions.set(boxDim.x,boxDim.y,boxDim.z);
boxDesc.localPose.t = NxVec3(0,boxDim.y,0);

// Set box up with CCD skeleton
boxDesc.ccdSkeleton = CreateCCDSkeleton(boxDim.x*0.8f);
...


how can i get the parameter "ccdSkeleton" in NxOgre? If this the same? :


NxOgre::BoxDescription bd;

bd.mSkeleton = CreateCCDSkeleton(boxDim.x*0.8f);


One more thing, is there any way i can "createCCDSkeleton" from a mesh, and in "offline mode", like we do with TriangleMeshes and ConvexMeshes with Flour?

Regards

Can you check first with spacegaier's guesses before confirming that CCD would the the problem?

Increasing skin width and iterator count seem plausible fixes.

I'm trying that fixes. Thanks

One thing, how can i use the iterator (NxOgre::CollisionModelIterator) that i get from
mBall->getShapes();

?

EDIT: On this line:

NxOgre::CollisionModelIterator it = mBall->getShapes();

i got this error:


Error 16 error LNK2019: unresolved external symbol "__declspec(dllimport) public: class NxOgre::const_ptr_vector_iterator<class NxOgre::Shape> __thiscall NxOgre::RigidBody::getShapes(void)const " (__imp_?getShapes@RigidBody@NxOgre@@QBE?AV?$const_ptr_vector_iterator@VShape@NxOgre@@@2@XZ) referenced in function "protected: virtual void __thiscall TestApp::createScene(void)" (?createScene@TestApp@@MAEXXZ) main.obj


Regards

I just wanted to try to help you, but I can't in my NxOgre version (latest BloodyMess), there is no CollisionModelIterator. Which version are you using?

EDIT: betajaen just told me, that you are probably using Detritus, which I am not right now, so I can#t help here...

2th EDIT: The whole thing couldn't work as some functions weren't coded yet, but - as always - betajaen is offering the best support available and coding them right now. In some minutes a new commit will be made to github and you are ready to go .

In some minutes a new commit will be made to github and you are ready to go .

Done.

Thanks a lot Will give it a try.

Really appreciated.