title: Several newbie questions for Physx 3
body: <p>Today, I tried to play around Physx and Physx visual debugger and as always, newbies have problems and questions. I'll try to describe my problems as best as I can with my poor english skills.</p>
  
  <p>1) I managed to create a physx scene. added a dynamic actor and manipulated it. I see in Visual Debugger it's motion. It's a standard PxSphereGeometry ball. However, when I add a second ball in the scene, the second one is not visible, but I can see that collision happens. Here's the code and if anyone can point me what's wrong with it I'd be very grateful:</p>
  
  <pre><code>PxMaterial* mMaterial;
  
  mMaterial = mPhysics-&gt;createMaterial(0.5f, 0.5f, 0.5f); //static friction, dynamic friction, restitution
  
  if(!mMaterial)
  error("createMaterial failed!");
  
  PxVec3 position(0, 50, 0);
  PxRigidDynamic* aSphereActor =  PxCreateDynamic(*mPhysics, PxTransform(position), PxSphereGeometry(3), *mMaterial, 1.f);
  PxRigidDynamic* aTrActor =  PxCreateDynamic(*mPhysics, PxTransform(PxVec3(3, 1, 1)), PxSphereGeometry(3), *mMaterial, 1.1f);
  
  if(!aSphereActor)
  error("Unable to create sphere actor");
  
  aSphereActor-&gt;setMass(1);
  
  aTrActor-&gt;setMass(10);
  
  PxRigidStatic* plane = PxCreatePlane(*mPhysics, PxPlane(PxVec3(0,1,0), 0), *mMaterial);
  if (!plane)
  error("create shape failed!");
  
  mScene-&gt;addActor(*plane);
  mScene-&gt;addActor(*aSphereActor);
  mScene-&gt;addActor(*aTrActor);
  
  
  while(true)
  {
  mScene-&gt;simulate(1.0f / 30.0f);
  if(!mScene-&gt;fetchResults(true))
  error("cant fetch result");
  Sleep(10);
  }
  </code></pre>
  
  <p>In this scene, aSphereActor collides with aTrActor, but I can't see aTrActor in Visual Debugger, however collision is perfectly visible.</p>
  
  <p>2) Nvidia's documentation is very very poor. It's a torture for newbies like me to find it's way through it. So I wanted to know how can I import a 3d model and add it in the scene. I know there is a Physx plugins for 3ds max, maya etc. Say I have a model exported with this plugin, how can I import it in my app and add it to the scene?</p>
  
  <p>3) During the creation of the scene</p>
  
  <pre><code>sceneDesc.gravity = PxVec3(0.0f, -9.81f, 0.0f);
  </code></pre>
  
  <p>, what value should I provide to get a real gravity, the one we have on earth </p>
  
  <p>4) I can assign a mass to an actor, however I don't know in which measurement unit the mass is. For example, if I set aSphereActor->setMass(1); will aSphereActor will be 1kg, gram or what?</p>
  
  <p>Thank you very much everyone. I appreciate your help. </p>