irrBullet 0.1.8 - Bullet physics wrapper

[cobra]

Hi everyone. I want to apologize for the lack of author support and updates to irrBullet. I haven't had time to help with problems or work on irrBullet and I'm not sure when I will have time.

I did have some time to check up on things, however, and I decided to let everyone know that irrBullet has not been abandoned. To show my appreciation to all of the irrBullet users, I made this small flag chart with 45 of the most popular user countries of 2011. Flag size represents the user mass of a country.




- Josiah

[Ravi08]

Hi, I was wondering if anyone could help me. I think I have problem with rigidbody/animated node.

I have an animated node which when hit falls down, now what happens is when hit the node animates and goes down but I dont think the rigidbody updates beacuse if I fire where the node started ie standing up, the bullet still collides with something.

Code for the animated node and rigidbody:

Code: Select all

IAnimatedMeshSceneNode* targetNode = (IAnimatedMeshSceneNode*)(device->getSceneManager()->getSceneNodeFromName("target"));
targetNode ->setCurrentFrame(0);
targetNode ->setAnimationSpeed(0);
 
ICollisionShape *targetShape = new IGImpactMeshShape(targetNode , device->getSceneManager()->getMesh("../../media/target.b3d"), 0);
IRigidBody *targetBody = world->addRigidBody(targetShape,COL_WORLD_OBJECT,worldObjectCollidesWith);
targetBody ->getAttributes()->addBool("target", true);

Code for when the target is hit:

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obj1->getAttributes()->setAttribute("target", false);
targetNode ->setFrameLoop(1,31);
targetNode ->setAnimationSpeed(10);
targetNode ->setLoopMode(false);

Sorry if this has been asked before, I couldn't find anything and thanks.

[Granyte]

right now i have an odd issue with irrbullet a strange windows apear in the middle of my screen and i can't interact with my program i'll post screen shot and code implying irrbullet

[cobra]

Granyte:
Is it Irrlicht's color-select dialog? What version of Irrlicht are you using? I've had this happen to me before but updating Irrlicht stopped the problem. I think 1.7 caused it.

Ravi08:
The rigidbody does not automatically scale with the bounding box of a scene node. You'll have to figure out a way to do that yourself because it's too specific to your game.

[Granyte]

i was using irrlicht 1.8.0 svn


i switched to usong bullet directly because i need colision with the terrain mesh but i'm now facing newer issues

[polylux]

Hey everyone.

I played with irrBullet quite a while ago and now it's time to fully integrate it into my project.
Similar to quite some users I'm facing a problem with adding my terrain scene node to the physics simulation. The scene node is correctly added to the sim world but other objects still pass through it.

Here's my approach:
From the terrain scene node's nature, it's not possible to get its standard IMesh but a mesh buffer from an arbitrary LOD. Hence I extended ITriangleMeshShape's functionality to also accept IMeshBuffers as a parameter as ITMS basically works on the mesh buffers of IMesh.

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void IBvhTriangleMeshShape::createShape(IMeshBuffer *meshBuffer)
{
    btBvhTriangleMeshShape* bvhShape =  new btBvhTriangleMeshShape(getTriangleMeshFromBuffer(meshBuffer), false, true);
    shape = bvhShape;
 
    calculateLocalInertia(getMass(), vector3df(0.0f,0.0f,0.0f));
}

On my side of the action, I use the following code to add terrain to the physics simulation:

Code: Select all

void OFLPhysics::addTerrain(scene::ITerrainSceneNode* terrain)
{
    OFLPhysics* inst = getInstance();
    scene::CDynamicMeshBuffer buf(irr::video::EVT_STANDARD,irr::video::EIT_16BIT);
    terrain->getMeshBufferForLOD(buf, 0);
    ICollisionShape* terrShape = new IBvhTriangleMeshShape(terrain, &buf, 0.f);
    terrShape->setMargin(.5f);
    IRigidBody* terrBody = inst->bWorld->addRigidBody(terrShape);
    terrBody->setCollisionFlags(ECF_STATIC_OBJECT);
}

Obviously, it fills a MeshBuffer object with data for a given LOD step which is then used to create bullet's representation of it.
Note that debugging shows the correct (similar) values as for verts- and triangle count.
Hence the questions are:
- Am I doing smth wrong?
- Am I missing smth?

All the other stuff collides as it should so I'm quite sure the sim is correctly set up.

Help greatly appreciated,
p.

[serengeor]

@polylux: are you trying to collide multiple IBvhTriangleMesh shapes? If so, that's the problem.

[polylux]

@polylux: are you trying to collide multiple IBvhTriangleMesh shapes? If so, that's the problem.

Thanks serengeor,
no, currently I only collide a cube with my terrain - so just one IBTM for the moment. Also, the terrain seems to be correctly handled as it starts to drift downwards as i assign mass to it.
Just to avoid problems in the future, what do you mean by 'collide multiple IBTMs'? Mean if there is more than one IBTM present or IBTMs that collide with each other?

p.

[serengeor]

Well it seams they are only intended to be for static usage (static level geometry) and nothing else. For example if you would drop one IBvhTriangleMeshShape onto another one it would simply just go trough it. So I think that applying mass to it would't be a good idea.

[polylux]

Well it seams they are only intended to be for static usage (static level geometry) and nothing else. For example if you would drop one IBvhTriangleMeshShape onto another one it would simply just go trough it. So I think that applying mass to it would't be a good idea.

thanks! never intended to anyways.
but still the problem remains. is there probably some mesh size constraint from bullet?

[serengeor]

is there probably some mesh size constraint from bullet?

I don't know if I understand you correctly, but here's a link where I think you could read up on that: http://www.bulletphysics.org/mediawiki- ... _The_World

[polylux]

Thanks again serengeor,

I am pretty sure it's no tunneling problem as the cube is sufficiently big (edge len: 3 units), falls down slowly and collides nicely with all other objects. Might need to debug further with the debug draw funcs. Will report back then.

p.

[polylux]

Well, seemingly it's the wrong way to create a triangle collision mesh from your terrain as with a sufficiently sized terrain the simulation pretty fast slows down to a slide show. Bullet offers the btHeightfieldTerrainShape (Link) for such things. I am currently very tempted to extend irrBullet's functionality by this - as long as no one else has done it already.
If so, just tell me please.

p.

[serengeor]

Well, seemingly it's the wrong way to create a triangle collision mesh from your terrain as with a sufficiently sized terrain the simulation pretty fast slows down to a slide show. Bullet offers the btHeightfieldTerrainShape (Link) for such things. I am currently very tempted to extend irrBullet's functionality by this - as long as no one else has done it already.
If so, just tell me please.

p.

How big was your terrain (how much vertices)?

[polylux]

Well, seemingly it's the wrong way to create a triangle collision mesh from your terrain as with a sufficiently sized terrain the simulation pretty fast slows down to a slide show. Bullet offers the btHeightfieldTerrainShape (Link) for such things. I am currently very tempted to extend irrBullet's functionality by this - as long as no one else has done it already.
If so, just tell me please.

p.

How big was your terrain (how much vertices)?

roughly 350k of verteces at LOD 0