I'm playing around with bullet a bit but i'm having some probs.
I have this small directx app that loads 2 .x files, one mesh is a simple flat terrain and the other just a sphere. Both exported from 3ds max using panda exporter.
I started by creating a collison box shape for the terrain and a sphere collision shape for the sphere object. All was working fine.
My goal is to use more complex models, like racing tracks, and after doing some reasearch in the forums, it seems that the btBvhTriangleMeshShape is the way the go if you want to handle collisions with such geometry.
I decided to create a btBvhTriangleMeshShape for my simple terrain but the collisions appear all messed up. As you can see in the image below, the sphere just stops in mid air!
Here's the code i use to set up objects:
Bullet initialization:
Code: Select all
void cPhysics::InitPhysics()
{
//Collision configuration contains default setup for memory, collision setup
physCollisionConfiguration = new btDefaultCollisionConfiguration();
//Use the default collision dispatcher. For parallel processing you can use a diffent dispatcher (see Extras/BulletMultiThreaded)
physDispatcher = new btCollisionDispatcher(physCollisionConfiguration);
physBroadphase = new btDbvtBroadphase();
//The default constraint solver. For parallel processing you can use a different solver (see Extras/BulletMultiThreaded)
physSolver = new btSequentialImpulseConstraintSolver;
//physSolver = solver;
//Create the main physics object
physDynamicsWorld = new btDiscreteDynamicsWorld(physDispatcher,physBroadphase,physSolver,physCollisionConfiguration);
physDynamicsWorld->setGravity(btVector3(0,-9.8f,0));
}The objects setup:
Code: Select all
struct TriMeshData
{
btScalar *vertices;
int *indices;
btTriangleIndexVertexArray *indexVertexArrays;
TriMeshData()
{
vertices = NULL;
indices = NULL;
indexVertexArrays = NULL;
}
~TriMeshData()
{
if( vertices ) delete [] vertices;
if( indices ) delete [] indices;
if( indexVertexArrays ) delete indexVertexArrays;
}
};
....
btCollisionShape* physSphereShape;
btRigidBody* physBoxBody;
btBvhTriangleMeshShape* physGroundShape;
btRigidBody* physGroundBody;
....
mPhysics = new cPhysics();
mPhysics->InitPhysics();
//Create the ground object
{
// Create the ground shape
//physGroundShape = new btBoxShape(btVector3(btScalar(50.0f),btScalar(0.0f),btScalar(50.0f)));
DWORD numVertices = mMesh->GetNumVertices();
DWORD numFaces = mMesh->GetNumFaces();
VertexPos *v = 0;
mMesh->LockVertexBuffer(0, (void**)&v);
// Extract vertices
pData = new TriMeshData();
pData->vertices = new btScalar[numVertices * 3];
for(UINT i = 0; i < numVertices; i++)
{
pData->vertices[i*3+0] = v[i].pos.x;
pData->vertices[i*3+1] = v[i].pos.y;
pData->vertices[i*3+2] = v[i].pos.z;
}
mMesh->UnlockVertexBuffer();
// Extract indices
pData->indices = new int[numFaces * 3];
WORD* ind = 0;
mMesh->LockIndexBuffer(0,(void**)&ind);
//memcpy( &indices, &ind, sizeof(ind));
for (int i=0;i < numFaces; i++)
{
pData->indices[i*3+0] = ind[i*3+0];
pData->indices[i*3+1] = ind[i*3+1];
pData->indices[i*3+2] = ind[i*3+2];
}
mMesh->UnlockIndexBuffer();
int indexStride = 3 * sizeof(int);
int vertStride = sizeof(btVector3);
pData->indexVertexArrays = new btTriangleIndexVertexArray(numFaces, pData->indices, indexStride,
numVertices, (btScalar*) &pData->vertices[0], sizeof(btScalar) * 3);
btTriangleMesh* trimesh = new btTriangleMesh();
for( DWORD i = 0; i < numFaces; i++ )
{
int index0 = pData->indices[i*3];
int index1 = pData->indices[i*3+1];
int index2 = pData->indices[i*3+2];
btVector3 vertex0(pData->vertices[index0*3], pData->vertices[index0*3+1],pData->vertices[index0*3+2]);
btVector3 vertex1(pData->vertices[index1*3], pData->vertices[index1*3+1],pData->vertices[index1*3+2]);
btVector3 vertex2(pData->vertices[index2*3], pData->vertices[index2*3+1],pData->vertices[index2*3+2]);
trimesh->addTriangle(vertex0,vertex1,vertex2);
}
bool useQuantizedAabbCompression = true;
//btVector3 aabbMin(-1000,-1000,-1000),aabbMax(1000,1000,1000);
physGroundShape = new btBvhTriangleMeshShape(trimesh, useQuantizedAabbCompression);
//physGroundShape = new btBvhTriangleMeshShape(pData->indexVertexArrays, useQuantizedAabbCompression);
// Set the position for the ground shape
//physGroundShape->calculateLocalInertia(0,btVector3(0, 0, 0));
btTransform groundTransform;
groundTransform.setIdentity();
groundTransform.setOrigin(btVector3(0, 0.0f, 0));
//physGroundShape->calculateLocalInertia(0,btVector3(0, 0, 0));
// Create MotionState and RigidBody object for the ground shape
btDefaultMotionState* myMotionState = new btDefaultMotionState(groundTransform);
btRigidBody::btRigidBodyConstructionInfo rbInfo(0, myMotionState, physGroundShape, btVector3(0, 0, 0));
physGroundBody = new btRigidBody(rbInfo);
// Add ground body to physics object
if (mPhysics && physGroundBody)
{
mPhysics->GetPhysicsWorld()->addRigidBody(physGroundBody);
}
physGroundBody->activate();
}
//Create the sphere object
{
//Create the box shape
float radius = 1.0f;
physSphereShape = new btSphereShape(radius);
//float const volume = (4.f / 3.f) * D3DX_PI * radius * radius * radius;
//btScalar const mass = volume * 5.0;
//Set mass, initial inertia and position for the box
float mass = 1.0f;
btVector3 inertia(0, 0, 0);
physSphereShape->calculateLocalInertia( mass, inertia );
btTransform startTransform;
startTransform.setIdentity();
startTransform.setOrigin(btVector3(0, 50, 0));
//Calculate the inertia
//physSphereShape->calculateLocalInertia(1.0, inertia);
// Create MotionState and RigidBody object for the box shape
btDefaultMotionState* myMotionState = new btDefaultMotionState(startTransform);
btRigidBody::btRigidBodyConstructionInfo rbInfo(mass, myMotionState, physSphereShape, inertia);
physBoxBody = new btRigidBody(rbInfo);
// Add box sphere to physics object & activate it
if (mPhysics)
{
mPhysics->GetPhysicsWorld()->addRigidBody(physBoxBody);
}
physBoxBody->activate();
//physBoxBody->setActivationState(2);
}
Any ideas what could be worng?
Thanks in advance
