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wrapped up first version of the FractureDemo

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move 'split impulse' / position solver before velocity solver, so that applied impulse is available for fracture
add btSliderConstraint::getAngularPos see http://code.google.com/p/bullet/issues/detail?id=489
This commit is contained in:
erwin.coumans
2011-03-18 00:20:52 +00:00
parent 74a65a6207
commit f17fa297d5
6 changed files with 172 additions and 149 deletions
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126
Demos/FractureDemo/btFractureDynamicsWorld.cpp
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@@ -7,17 +7,19 @@
btFractureDynamicsWorld::btFractureDynamicsWorld ( btDispatcher* dispatcher,btBroadphaseInterface* pairCache,btConstraintSolver* constraintSolver,btCollisionConfiguration* collisionConfiguration)
:btDiscreteDynamicsWorld(dispatcher,pairCache,constraintSolver,collisionConfiguration),
m_fracturingMode(false)
m_fracturingMode(true)
{
}
void btFractureDynamicsWorld::glueCallback(btScalar timeStep)
void btFractureDynamicsWorld::glueCallback()
{
int numManifolds = getDispatcher()->getNumManifolds();
///first build the islands based on axis aligned bounding box overlap
btUnionFind unionFind;
int index = 0;
@@ -61,7 +63,7 @@ void btFractureDynamicsWorld::glueCallback(btScalar timeStep)
btRigidBody* body0 = btRigidBody::upcast(colObj0);
btRigidBody* body1 = btRigidBody::upcast(colObj1);
if (!colObj0->isStaticOrKinematicObject() && !colObj1->isStaticOrKinematicObject())
{
unionFind.unite(tag0, tag1);
@@ -70,7 +72,7 @@ void btFractureDynamicsWorld::glueCallback(btScalar timeStep)
numElem = unionFind.getNumElements();
@@ -82,9 +84,9 @@ void btFractureDynamicsWorld::glueCallback(btScalar timeStep)
if (!collisionObject->isStaticOrKinematicObject())
{
int tag = unionFind.find(index);
collisionObject->setIslandTag( tag);
//Set the correct object offset in Collision Object Array
#if STATIC_SIMULATION_ISLAND_OPTIMIZATION
unionFind.getElement(index).m_sz = ai;
@@ -102,7 +104,7 @@ void btFractureDynamicsWorld::glueCallback(btScalar timeStep)
btAlignedObjectArray<btCollisionObject*> removedObjects;
//update the sleeping state for bodies, if all are sleeping
///iterate over all islands
for ( startIslandIndex=0;startIslandIndex<numElem;startIslandIndex = endIslandIndex)
{
int islandId = unionFind.getElement(startIslandIndex).m_id;
@@ -129,19 +131,25 @@ void btFractureDynamicsWorld::glueCallback(btScalar timeStep)
numObjects++;
}
///Then for each island that contains at least two objects and one fracture object
if (fractureObjectIndex>=0 && numObjects>1)
{
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
btFractureBody* fracObj = (btFractureBody*)getCollisionObjectArray()[fractureObjectIndex];
///glueing objects means creating a new compound and removing the old objects
///delay the removal of old objects to avoid array indexing problems
removedObjects.push_back(fracObj);
m_fractureBodies.remove(fracObj);
btAlignedObjectArray<btScalar> massArray;
btAlignedObjectArray<btVector3> oldImpulses;
btAlignedObjectArray<btVector3> oldCenterOfMassesWS;
oldImpulses.push_back(fracObj->getLinearVelocity()/1./fracObj->getInvMass());
oldCenterOfMassesWS.push_back(fracObj->getCenterOfMassPosition());
btScalar totalMass = 0.f;
@@ -169,7 +177,7 @@ void btFractureDynamicsWorld::glueCallback(btScalar timeStep)
for (idx=startIslandIndex;idx<endIslandIndex;idx++)
{
int i = unionFind.getElement(idx).m_sz;
if (i==fractureObjectIndex)
@@ -178,9 +186,15 @@ void btFractureDynamicsWorld::glueCallback(btScalar timeStep)
btCollisionObject* otherCollider = getCollisionObjectArray()[i];
btRigidBody* otherObject = btRigidBody::upcast(otherCollider);
//don't glue/merge with static objects right now, otherwise everything gets stuck to the ground
///todo: expose this as a callback
if (!otherObject || !otherObject->getInvMass())
continue;
oldImpulses.push_back(otherObject->getLinearVelocity()*(1.f/otherObject->getInvMass()));
oldCenterOfMassesWS.push_back(otherObject->getCenterOfMassPosition());
removedObjects.push_back(otherObject);
m_fractureBodies.remove((btFractureBody*)otherObject);
@@ -208,7 +222,7 @@ void btFractureDynamicsWorld::glueCallback(btScalar timeStep)
totalMass+=curMass;
}
btTransform shift;
shift.setIdentity();
@@ -221,12 +235,22 @@ void btFractureDynamicsWorld::glueCallback(btScalar timeStep)
btFractureBody* newBody = new btFractureBody(totalMass,0,newCompound,localInertia, &massArray[0], numChildren,this);
newBody->recomputeConnectivity(this);
newBody->setWorldTransform(fracObj->getWorldTransform()*shift);
//now the linear/angular velocity is still zero, apply the impulses
for (int i=0;i<oldImpulses.size();i++)
{
btVector3 rel_pos = oldCenterOfMassesWS[i]-newBody->getCenterOfMassPosition();
const btVector3& imp = oldImpulses[i];
newBody->applyImpulse(imp, rel_pos);
}
addRigidBody(newBody);
}
}
//remove the objects from the world at the very end,
@@ -255,24 +279,22 @@ struct btFracturePair
void btFractureDynamicsWorld::solveConstraints(btContactSolverInfo& solverInfo)
{
//todo: add some logic
// save all velocities
// 1) that if a fracture object break
// 2) revert all velocties
// 3) apply impulses for the fracture bodies at the contact locations
// 4)and run the constaint solver again
// todo: after fracture we should run the solver again for better realism
// for example
// save all velocities and if one or more objects fracture:
// 1) revert all velocties
// 2) apply impulses for the fracture bodies at the contact locations
// 3)and run the constaint solver again
btDiscreteDynamicsWorld::solveConstraints(solverInfo);
fractureCallback(solverInfo.m_timeStep);
fractureCallback();
}
void btFractureDynamicsWorld::addNewBody(const btTransform& oldTransform,btScalar* masses, btCompoundShape* oldCompound)
btFractureBody* btFractureDynamicsWorld::addNewBody(const btTransform& oldTransform,btScalar* masses, btCompoundShape* oldCompound)
{
int i;
btTransform shift;
shift.setIdentity();
btVector3 localInertia;
@@ -284,10 +306,11 @@ void btFractureDynamicsWorld::addNewBody(const btTransform& oldTransform,btScala
btFractureBody* newBody = new btFractureBody(totalMass,0,newCompound,localInertia, masses,newCompound->getNumChildShapes(), this);
newBody->recomputeConnectivity(this);
newBody->setCollisionFlags(newBody->getCollisionFlags()|btCollisionObject::CF_CUSTOM_MATERIAL_CALLBACK);
newBody->setWorldTransform(oldTransform*shift);
addRigidBody(newBody);
return newBody;
}
void btFractureDynamicsWorld::addRigidBody(btRigidBody* body)
@@ -351,7 +374,7 @@ void btFractureDynamicsWorld::breakDisconnectedParts( btFractureBody* fracObj)
}
}
numElem = unionFind.getNumElements();
index=0;
for (int ai=0;ai<numChildren;ai++)
{
@@ -398,30 +421,34 @@ void btFractureDynamicsWorld::breakDisconnectedParts( btFractureBody* fracObj)
}
if (numShapes)
{
addNewBody(fracObj->getWorldTransform(),&masses[0],newCompound);
btFractureBody* newBody = addNewBody(fracObj->getWorldTransform(),&masses[0],newCompound);
newBody->setLinearVelocity(fracObj->getLinearVelocity());
newBody->setAngularVelocity(fracObj->getAngularVelocity());
numIslands++;
}
}
removeRigidBody(fracObj);//should it also be removed from the array?
}
#include <stdio.h>
void btFractureDynamicsWorld::fractureCallback( btScalar timeStep)
void btFractureDynamicsWorld::fractureCallback( )
{
btAlignedObjectArray<btFracturePair> sFracturePairs;
if (!m_fracturingMode)
{
glueCallback(timeStep);
glueCallback();
return;
}
@@ -429,28 +456,31 @@ void btFractureDynamicsWorld::fractureCallback( btScalar timeStep)
sFracturePairs.clear();
for (int i=0;i<numManifolds;i++)
{
btPersistentManifold* manifold = getDispatcher()->getManifoldByIndexInternal(i);
if (!manifold->getNumContacts())
continue;
btScalar totalImpact = 0.f;
for (int p=0;p<manifold->getNumContacts();p++)
{
totalImpact += manifold->getContactPoint(p).m_appliedImpulse;
}
// printf("totalImpact=%f\n",totalImpact);
static float maxImpact = 0;
if (totalImpact>maxImpact)
maxImpact = totalImpact;
//some threshold otherwise resting contact would break objects after a while
if (totalImpact < 10)
if (totalImpact < 40.f)
continue;
// printf("strong impact\n");
// printf("strong impact\n");
//@todo: add better logic to decide what parts to fracture
@@ -479,8 +509,8 @@ void btFractureDynamicsWorld::fractureCallback( btScalar timeStep)
btCollisionObject* colOb = (btCollisionObject*)manifold->getBody1();
btRigidBody* otherOb = btRigidBody::upcast(colOb);
// if (!otherOb->getInvMass())
// continue;
// if (!otherOb->getInvMass())
// continue;
int pi=-1;
@@ -504,16 +534,16 @@ void btFractureDynamicsWorld::fractureCallback( btScalar timeStep)
sFracturePairs[pi].m_contactManifolds.push_back(manifold);
}
}
if (f1 < m_fractureBodies.size())
{
int j=f1;
{
btCollisionObject* colOb = (btCollisionObject*)manifold->getBody0();
btRigidBody* otherOb = btRigidBody::upcast(colOb);
// if (!otherOb->getInvMass())
// continue;
// if (!otherOb->getInvMass())
// continue;
int pi=-1;
@@ -549,7 +579,7 @@ void btFractureDynamicsWorld::fractureCallback( btScalar timeStep)
{
// printf("fracturing\n");
// printf("fracturing\n");
for (int i=0;i<sFracturePairs.size();i++)
{
@@ -559,7 +589,7 @@ void btFractureDynamicsWorld::fractureCallback( btScalar timeStep)
//compute connectivity of connected child shapes
if (sFracturePairs[i].m_fracObj->getCollisionShape()->isCompound())
{
btTransform tr;
@@ -585,7 +615,7 @@ void btFractureDynamicsWorld::fractureCallback( btScalar timeStep)
{
btConnection& connection = sFracturePairs[i].m_fracObj->m_connections[f];
if ( (connection.m_childIndex0 == pt.m_index0) ||
(connection.m_childIndex1 == pt.m_index0)
(connection.m_childIndex1 == pt.m_index0)
)
{
connection.m_strength -= pt.m_appliedImpulse;
@@ -603,7 +633,7 @@ void btFractureDynamicsWorld::fractureCallback( btScalar timeStep)
{
btConnection& connection = sFracturePairs[i].m_fracObj->m_connections[f];
if ( (connection.m_childIndex0 == pt.m_index1) ||
(connection.m_childIndex1 == pt.m_index1)
(connection.m_childIndex1 == pt.m_index1)
)
{
connection.m_strength -= pt.m_appliedImpulse;