ConvexHull not colliding

[nathanf534]

I have 2 convex hulls, and I can't get them to collide. I am assuming I created the hull with incorrect values, but Im not sure. I am using Irrlicht. Here is where I create the hull collision

Code: Select all

void PhysicsManager::addHullCollisionBody(IMeshSceneNode* node){//creates the HullCollisionBody
   NewtonCollision* collision =NewtonCreateConvexHull(nWorld,4,(const float*)(node->getMesh()->getMeshBuffer(0)->getVertices()),12,0,0,NULL);
   NewtonBody* body=NewtonCreateBody(nWorld,collision);
   cout<<"body:"<<body<<endl;
   UserData* userData = new UserData;
   cout<<"userData:"<<userData<<endl;
   userData->node=node;
   userData->physicsManager=this;
   userData->body=body;
   NewtonBodySetUserData(body,userData);
   NewtonBodySetForceAndTorqueCallback(body,ApplyForceAndTorqueEvent);
   NewtonBodySetTransformCallback(body,callbackTransform);
   matrix4 mat=node->getAbsoluteTransformation();
   NewtonBodySetMatrix(body, &mat.M[0]);
   NewtonBodySetMassMatrix(body,1,1,1,1);
   node->setID((int)((void*)userData));
}


and these are my 2 callbacks

Code: Select all

void _cdecl ApplyForceAndTorqueEvent (const NewtonBody* body,float matrix,int x){
   float torque[3];
   float force[3];
   PhysicsManager::UserData* data=(PhysicsManager::UserData*)NewtonBodyGetUserData(body);
   data->addForce.getAs4Values(force);
   data->addTorque.getAs4Values(torque);
   NewtonBodyAddTorque (body,torque);
   NewtonBodyAddForce (body,force);
   NewtonBodySetAutoSleep(body,0);
}
void _cdecl callbackTransform( const NewtonBody* body, const float* matrix,int x){
   matrix4 mat;
   mat.setM(matrix);
   PhysicsManager::UserData* data = (PhysicsManager::UserData*)NewtonBodyGetUserData(body);
   if (data->node){
      data->node->setPosition(mat.getTranslation());
      data->node->setRotation(mat.getRotationDegrees());
   }
}

[JernejL]

You gave insufficient information on the problem, I suggest you implement a debug renderer to visualise the world and shapes you created and post a few screenshots.

[nathanf534]

ok, here is a screenshot of the hull collision... it is just a triangle.

[nathanf534]

by changing the second parameter of NewtonCreateConvexHull from 4 to 2000, it works perfectly. What exactly does that second parameter do? I just figured out 2000 by guess and check, and anything above that made my program crash.

here is the picture with the 2nd parameter at 2000

[Julio Jerez]

It is not a random value it is the number of veritices in the vertex list.
from where you get 4 and 2000 figure? you should pass the exact number of vertices in the mesh

hopefully when the new editor comes on line, thes confusion will go away, because those model will be put together visually.

[nathanf534]

it is the number of veritices in the vertex list.

well that would have been helpful to know, all the wiki says is

dFloat count - number of consecutive points to follow (must be at least 4).

which just made me confused... it could have just said number of vertices.

Anyway, thanks for the help.

[JernejL]

It is number of vertices / points, it says it.. and it builds a convex hull to wrap around the vertex cloud that you send it.

[Stucuk]

If your supplying it vertex's and a parameter is called "Count" then no matter what the description is you should know it means the amount of whatever your giving the procedure. I have updated the WIKI page.

dFloat count - number of points/vertices sent in vertexCloud (must be at least 4).

[Aldeminor]

How to visualize result of NewtonCreateConvexHull?

[Julio Jerez]

use debug display

[Aldeminor]

How can I see that window if I'm using wrapper betwen Newton double-precision dll and C#?

[Julio Jerez]

the debug display are funstion of the engine, you wrapre need to support then,

[Stucuk]

Debug display has to be implemented on the application that renders the scene. Newton doesn't render anything to your application. The SDK Demos have a debug display implemented.