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add correct impulse matrix to multibody-deformable contact

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This commit is contained in:
Xuchen Han
2019-07-24 16:01:47 -07:00
parent 243b9fc8c7
commit 233a381e7c
14 changed files with 618 additions and 594 deletions
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46
examples/DeformableContact/DeformableContact.cpp
View File

@@ -69,10 +69,10 @@ public:
void resetCamera()
{
float dist = 15;
float dist = 30;
float pitch = -30;
float yaw = 100;
float targetPos[3] = {0, -3, 0};
float targetPos[3] = {0, -10, 0};
m_guiHelper->resetCamera(dist, yaw, pitch, targetPos[0], targetPos[1], targetPos[2]);
}
@@ -140,7 +140,7 @@ void DeformableContact::initPhysics()
btTransform groundTransform;
groundTransform.setIdentity();
groundTransform.setOrigin(btVector3(0, -40, 0));
groundTransform.setRotation(btQuaternion(btVector3(1, 0, 0), SIMD_PI * 0.1));
groundTransform.setRotation(btQuaternion(btVector3(1, 0, 0), SIMD_PI * 0.));
//We can also use DemoApplication::localCreateRigidBody, but for clarity it is provided here:
btScalar mass(0.);
@@ -163,16 +163,16 @@ void DeformableContact::initPhysics()
{
bool damping = false;
bool damping = true;
bool gyro = false;
int numLinks = 0;
bool spherical = true; //set it ot false -to use 1DoF hinges instead of 3DoF sphericals
int numLinks = 4;
bool spherical = false; //set it ot false -to use 1DoF hinges instead of 3DoF sphericals
bool canSleep = false;
bool selfCollide = true;
btVector3 linkHalfExtents(1, 1, 1);
btVector3 baseHalfExtents(1, 1, 1);
btMultiBody* mbC = createFeatherstoneMultiBody_testMultiDof(m_dynamicsWorld, numLinks, btVector3(0.f, 2.f,0.f), linkHalfExtents, baseHalfExtents, spherical, g_floatingBase);
btMultiBody* mbC = createFeatherstoneMultiBody_testMultiDof(m_dynamicsWorld, numLinks, btVector3(0.f, 10.f,0.f), linkHalfExtents, baseHalfExtents, spherical, g_floatingBase);
mbC->setCanSleep(canSleep);
mbC->setHasSelfCollision(selfCollide);
@@ -180,13 +180,13 @@ void DeformableContact::initPhysics()
//
if (!damping)
{
mbC->setLinearDamping(0.f);
mbC->setAngularDamping(0.f);
mbC->setLinearDamping(0.0f);
mbC->setAngularDamping(0.0f);
}
else
{
mbC->setLinearDamping(0.1f);
mbC->setAngularDamping(0.9f);
mbC->setLinearDamping(0.04f);
mbC->setAngularDamping(0.04f);
}
if (numLinks > 0)
@@ -209,22 +209,24 @@ void DeformableContact::initPhysics()
// create a patch of cloth
{
btScalar h = 0;
const btScalar s = 4;
btSoftBody* psb = btSoftBodyHelpers::CreatePatch(getDeformableDynamicsWorld()->getWorldInfo(), btVector3(-s, 0, -s),
btVector3(+s, 0, -s),
btVector3(-s, 0, +s),
btVector3(+s, 0, +s),
// 20,20,
3,3,
btSoftBody* psb = btSoftBodyHelpers::CreatePatch(getDeformableDynamicsWorld()->getWorldInfo(), btVector3(-s, h, -s),
btVector3(+s, h, -s),
btVector3(-s, h, +s),
btVector3(+s, h, +s),
20,20,
// 3,3,
1 + 2 + 4 + 8, true);
psb->getCollisionShape()->setMargin(0.25);
psb->generateBendingConstraints(2);
psb->setTotalMass(.5);
psb->setTotalMass(5);
psb->setSpringStiffness(2);
psb->setDampingCoefficient(0.01);
psb->m_cfg.kKHR = 1; // collision hardness with kinematic objects
psb->m_cfg.kCHR = 1; // collision hardness with rigid body
psb->m_cfg.kDF = 0;
psb->m_cfg.kDF = .1;
getDeformableDynamicsWorld()->addSoftBody(psb);
}
@@ -271,7 +273,7 @@ void DeformableContact::exitPhysics()
void DeformableContact::stepSimulation(float deltaTime)
{
// getDeformableDynamicsWorld()->getMultiBodyDynamicsWorld()->stepSimulation(deltaTime);
m_dynamicsWorld->stepSimulation(deltaTime, 4, 1./240.);
m_dynamicsWorld->stepSimulation(deltaTime, 5, 1./250.);
}
@@ -279,7 +281,7 @@ btMultiBody* DeformableContact::createFeatherstoneMultiBody_testMultiDof(btMulti
{
//init the base
btVector3 baseInertiaDiag(0.f, 0.f, 0.f);
float baseMass = .05f;
float baseMass = .1f;
if (baseMass)
{
@@ -300,7 +302,7 @@ btMultiBody* DeformableContact::createFeatherstoneMultiBody_testMultiDof(btMulti
//init the links
btVector3 hingeJointAxis(1, 0, 0);
float linkMass = .05f;
float linkMass = .1f;
btVector3 linkInertiaDiag(0.f, 0.f, 0.f);
btCollisionShape* pTempBox = new btBoxShape(btVector3(linkHalfExtents[0], linkHalfExtents[1], linkHalfExtents[2]));

2
examples/ExampleBrowser/ExampleEntries.cpp
View File

@@ -50,6 +50,7 @@
#include "../DeformableDemo/DeformableDemo.h"
#include "../Pinch/Pinch.h"
#include "../DeformableContact/DeformableContact.h"
#include "../MultiBodyBaseline/MultiBodyBaseline.h"
#include "../VolumetricDeformable/VolumetricDeformable.h"
#include "../SharedMemory/PhysicsServerExampleBullet2.h"
#include "../SharedMemory/PhysicsServerExample.h"
@@ -126,6 +127,7 @@ static ExampleEntry gDefaultExamples[] =
ExampleEntry(0, "Grasp Deformable Cube", "Grasping test", PinchCreateFunc),
ExampleEntry(0, "Volumetric Deformable Objects", "Volumetric Deformable test", VolumetricDeformableCreateFunc),
ExampleEntry(0, "Deformable-MultiBody Contact", "MultiBody and Deformable contact", DeformableContactCreateFunc),
ExampleEntry(0, "MultiBody Baseline", "MultiBody Baseline", MultiBodyBaselineCreateFunc),
ExampleEntry(1, "Constraints", "Show the use of the various constraints in Bullet. Press the L key to visualize the constraint limits. Press the C key to visualize the constraint frames.",
AllConstraintCreateFunc),

358
examples/MultiBodyBaseline/MultiBodyBaseline.cpp Normal file
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@@ -0,0 +1,358 @@
/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
This software is provided 'as-is', without any express or implied warranty.
In no event will the authors be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it freely,
subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
///create 125 (5x5x5) dynamic object
#define ARRAY_SIZE_X 5
#define ARRAY_SIZE_Y 5
#define ARRAY_SIZE_Z 5
//maximum number of objects (and allow user to shoot additional boxes)
#define MAX_PROXIES (ARRAY_SIZE_X * ARRAY_SIZE_Y * ARRAY_SIZE_Z + 1024)
///scaling of the objects (0.1 = 20 centimeter boxes )
#define SCALING 1.
#define START_POS_X -5
#define START_POS_Y -5
#define START_POS_Z -3
#include "MultiBodyBaseline.h"
///btBulletDynamicsCommon.h is the main Bullet include file, contains most common include files.
#include "btBulletDynamicsCommon.h"
#include "BulletSoftBody/btDeformableRigidDynamicsWorld.h"
#include "BulletSoftBody/btSoftBody.h"
#include "BulletSoftBody/btSoftBodyHelpers.h"
#include "BulletSoftBody/btDeformableBodySolver.h"
#include "BulletSoftBody/btSoftBodyRigidBodyCollisionConfiguration.h"
#include "BulletDynamics/Featherstone/btMultiBodyConstraintSolver.h"
#include <stdio.h> //printf debugging
#include "../CommonInterfaces/CommonRigidBodyBase.h"
#include "../Utils/b3ResourcePath.h"
#include "../SoftDemo/BunnyMesh.h"
#include "BulletDynamics/Featherstone/btMultiBodyLinkCollider.h"
#include "BulletDynamics/Featherstone/btMultiBodyJointFeedback.h"
#include "../CommonInterfaces/CommonMultiBodyBase.h"
#include "../Utils/b3ResourcePath.h"
///The MultiBodyBaseline demo deformable bodies self-collision
static bool g_floatingBase = true;
static float friction = 1.;
class MultiBodyBaseline : public CommonMultiBodyBase
{
btMultiBody* m_multiBody;
btAlignedObjectArray<btMultiBodyJointFeedback*> m_jointFeedbacks;
public:
MultiBodyBaseline(struct GUIHelperInterface* helper)
: CommonMultiBodyBase(helper)
{
}
virtual ~MultiBodyBaseline()
{
}
void initPhysics();
void exitPhysics();
void resetCamera()
{
float dist = 30;
float pitch = -30;
float yaw = 100;
float targetPos[3] = {0, -10, 0};
m_guiHelper->resetCamera(dist, yaw, pitch, targetPos[0], targetPos[1], targetPos[2]);
}
virtual void stepSimulation(float deltaTime);
btMultiBody* createFeatherstoneMultiBody_testMultiDof(class btMultiBodyDynamicsWorld* world, int numLinks, const btVector3& basePosition, const btVector3& baseHalfExtents, const btVector3& linkHalfExtents, bool spherical = false, bool floating = false);
void addColliders_testMultiDof(btMultiBody* pMultiBody, btMultiBodyDynamicsWorld* pWorld, const btVector3& baseHalfExtents, const btVector3& linkHalfExtents);
};
void MultiBodyBaseline::initPhysics()
{
m_guiHelper->setUpAxis(1);
///collision configuration contains default setup for memory, collision setup
m_collisionConfiguration = new btSoftBodyRigidBodyCollisionConfiguration();
///use the default collision dispatcher. For parallel processing you can use a diffent dispatcher (see Extras/BulletMultiThreaded)
m_dispatcher = new btCollisionDispatcher(m_collisionConfiguration);
m_broadphase = new btDbvtBroadphase();
btMultiBodyConstraintSolver* sol;
sol = new btMultiBodyConstraintSolver;
m_solver = sol;
btMultiBodyDynamicsWorld* world = new btMultiBodyDynamicsWorld(m_dispatcher, m_broadphase, sol, m_collisionConfiguration);
m_dynamicsWorld = world;
// m_dynamicsWorld->setDebugDrawer(&gDebugDraw);
m_guiHelper->createPhysicsDebugDrawer(m_dynamicsWorld);
m_dynamicsWorld->setGravity(btVector3(0, -10, 0));
{
///create a ground
btCollisionShape* groundShape = new btBoxShape(btVector3(btScalar(150.), btScalar(25.), btScalar(150.)));
m_collisionShapes.push_back(groundShape);
btTransform groundTransform;
groundTransform.setIdentity();
groundTransform.setOrigin(btVector3(0, -40, 0));
groundTransform.setRotation(btQuaternion(btVector3(1, 0, 0), SIMD_PI * 0.));
//We can also use DemoApplication::localCreateRigidBody, but for clarity it is provided here:
btScalar mass(0.);
//rigidbody is dynamic if and only if mass is non zero, otherwise static
bool isDynamic = (mass != 0.f);
btVector3 localInertia(0, 0, 0);
if (isDynamic)
groundShape->calculateLocalInertia(mass, localInertia);
//using motionstate is recommended, it provides interpolation capabilities, and only synchronizes 'active' objects
btDefaultMotionState* myMotionState = new btDefaultMotionState(groundTransform);
btRigidBody::btRigidBodyConstructionInfo rbInfo(mass, myMotionState, groundShape, localInertia);
btRigidBody* body = new btRigidBody(rbInfo);
body->setFriction(0.5);
//add the ground to the dynamics world
m_dynamicsWorld->addRigidBody(body,1,1+2);
}
{
bool damping = true;
bool gyro = false;
int numLinks = 4;
bool spherical = false; //set it ot false -to use 1DoF hinges instead of 3DoF sphericals
bool canSleep = false;
bool selfCollide = true;
btVector3 linkHalfExtents(1, 1, 1);
btVector3 baseHalfExtents(1, 1, 1);
btMultiBody* mbC = createFeatherstoneMultiBody_testMultiDof(m_dynamicsWorld, numLinks, btVector3(0.f, 10.f,0.f), linkHalfExtents, baseHalfExtents, spherical, g_floatingBase);
mbC->setCanSleep(canSleep);
mbC->setHasSelfCollision(selfCollide);
mbC->setUseGyroTerm(gyro);
//
if (!damping)
{
mbC->setLinearDamping(0.0f);
mbC->setAngularDamping(0.0f);
}
else
{
mbC->setLinearDamping(0.04f);
mbC->setAngularDamping(0.04f);
}
if (numLinks > 0)
{
btScalar q0 = 0.f * SIMD_PI / 180.f;
if (!spherical)
{
mbC->setJointPosMultiDof(0, &q0);
}
else
{
btQuaternion quat0(btVector3(1, 1, 0).normalized(), q0);
quat0.normalize();
mbC->setJointPosMultiDof(0, quat0);
}
}
///
addColliders_testMultiDof(mbC, m_dynamicsWorld, baseHalfExtents, linkHalfExtents);
}
m_guiHelper->autogenerateGraphicsObjects(m_dynamicsWorld);
}
void MultiBodyBaseline::exitPhysics()
{
//cleanup in the reverse order of creation/initialization
//remove the rigidbodies from the dynamics world and delete them
int i;
for (i = m_dynamicsWorld->getNumCollisionObjects() - 1; i >= 0; i--)
{
btCollisionObject* obj = m_dynamicsWorld->getCollisionObjectArray()[i];
btRigidBody* body = btRigidBody::upcast(obj);
if (body && body->getMotionState())
{
delete body->getMotionState();
}
m_dynamicsWorld->removeCollisionObject(obj);
delete obj;
}
//delete collision shapes
for (int j = 0; j < m_collisionShapes.size(); j++)
{
btCollisionShape* shape = m_collisionShapes[j];
delete shape;
}
m_collisionShapes.clear();
delete m_dynamicsWorld;
delete m_solver;
delete m_broadphase;
delete m_dispatcher;
delete m_collisionConfiguration;
}
void MultiBodyBaseline::stepSimulation(float deltaTime)
{
// getDeformableDynamicsWorld()->getMultiBodyDynamicsWorld()->stepSimulation(deltaTime);
m_dynamicsWorld->stepSimulation(deltaTime, 5, 1./250.);
}
btMultiBody* MultiBodyBaseline::createFeatherstoneMultiBody_testMultiDof(btMultiBodyDynamicsWorld* pWorld, int numLinks, const btVector3& basePosition, const btVector3& baseHalfExtents, const btVector3& linkHalfExtents, bool spherical, bool floating)
{
//init the base
btVector3 baseInertiaDiag(0.f, 0.f, 0.f);
float baseMass = .1f;
if (baseMass)
{
btCollisionShape* pTempBox = new btBoxShape(btVector3(baseHalfExtents[0], baseHalfExtents[1], baseHalfExtents[2]));
pTempBox->calculateLocalInertia(baseMass, baseInertiaDiag);
delete pTempBox;
}
bool canSleep = false;
btMultiBody* pMultiBody = new btMultiBody(numLinks, baseMass, baseInertiaDiag, !floating, canSleep);
btQuaternion baseOriQuat(0.f, 0.f, 0.f, 1.f);
pMultiBody->setBasePos(basePosition);
pMultiBody->setWorldToBaseRot(baseOriQuat);
btVector3 vel(0, 0, 0);
// pMultiBody->setBaseVel(vel);
//init the links
btVector3 hingeJointAxis(1, 0, 0);
float linkMass = .1f;
btVector3 linkInertiaDiag(0.f, 0.f, 0.f);
btCollisionShape* pTempBox = new btBoxShape(btVector3(linkHalfExtents[0], linkHalfExtents[1], linkHalfExtents[2]));
pTempBox->calculateLocalInertia(linkMass, linkInertiaDiag);
delete pTempBox;
//y-axis assumed up
btVector3 parentComToCurrentCom(0, -linkHalfExtents[1] * 2.f, 0); //par body's COM to cur body's COM offset
btVector3 currentPivotToCurrentCom(0, -linkHalfExtents[1], 0); //cur body's COM to cur body's PIV offset
btVector3 parentComToCurrentPivot = parentComToCurrentCom - currentPivotToCurrentCom; //par body's COM to cur body's PIV offset
//////
btScalar q0 = 0.f * SIMD_PI / 180.f;
btQuaternion quat0(btVector3(0, 1, 0).normalized(), q0);
quat0.normalize();
/////
for (int i = 0; i < numLinks; ++i)
{
if (!spherical)
pMultiBody->setupRevolute(i, linkMass, linkInertiaDiag, i - 1, btQuaternion(0.f, 0.f, 0.f, 1.f), hingeJointAxis, parentComToCurrentPivot, currentPivotToCurrentCom, true);
else
//pMultiBody->setupPlanar(i, linkMass, linkInertiaDiag, i - 1, btQuaternion(0.f, 0.f, 0.f, 1.f)/*quat0*/, btVector3(1, 0, 0), parentComToCurrentPivot*2, false);
pMultiBody->setupSpherical(i, linkMass, linkInertiaDiag, i - 1, btQuaternion(0.f, 0.f, 0.f, 1.f), parentComToCurrentPivot, currentPivotToCurrentCom, true);
}
pMultiBody->finalizeMultiDof();
///
pWorld->addMultiBody(pMultiBody);
///
return pMultiBody;
}
void MultiBodyBaseline::addColliders_testMultiDof(btMultiBody* pMultiBody, btMultiBodyDynamicsWorld* pWorld, const btVector3& baseHalfExtents, const btVector3& linkHalfExtents)
{
btAlignedObjectArray<btQuaternion> world_to_local;
world_to_local.resize(pMultiBody->getNumLinks() + 1);
btAlignedObjectArray<btVector3> local_origin;
local_origin.resize(pMultiBody->getNumLinks() + 1);
world_to_local[0] = pMultiBody->getWorldToBaseRot();
local_origin[0] = pMultiBody->getBasePos();
{
// float pos[4]={local_origin[0].x(),local_origin[0].y(),local_origin[0].z(),1};
btScalar quat[4] = {-world_to_local[0].x(), -world_to_local[0].y(), -world_to_local[0].z(), world_to_local[0].w()};
if (1)
{
btCollisionShape* box = new btBoxShape(baseHalfExtents);
btMultiBodyLinkCollider* col = new btMultiBodyLinkCollider(pMultiBody, -1);
col->setCollisionShape(box);
btTransform tr;
tr.setIdentity();
tr.setOrigin(local_origin[0]);
tr.setRotation(btQuaternion(quat[0], quat[1], quat[2], quat[3]));
col->setWorldTransform(tr);
pWorld->addCollisionObject(col, 2, 1 + 2);
col->setFriction(friction);
pMultiBody->setBaseCollider(col);
}
}
for (int i = 0; i < pMultiBody->getNumLinks(); ++i)
{
const int parent = pMultiBody->getParent(i);
world_to_local[i + 1] = pMultiBody->getParentToLocalRot(i) * world_to_local[parent + 1];
local_origin[i + 1] = local_origin[parent + 1] + (quatRotate(world_to_local[i + 1].inverse(), pMultiBody->getRVector(i)));
}
for (int i = 0; i < pMultiBody->getNumLinks(); ++i)
{
btVector3 posr = local_origin[i + 1];
// float pos[4]={posr.x(),posr.y(),posr.z(),1};
btScalar quat[4] = {-world_to_local[i + 1].x(), -world_to_local[i + 1].y(), -world_to_local[i + 1].z(), world_to_local[i + 1].w()};
btCollisionShape* box = new btBoxShape(linkHalfExtents);
btMultiBodyLinkCollider* col = new btMultiBodyLinkCollider(pMultiBody, i);
col->setCollisionShape(box);
btTransform tr;
tr.setIdentity();
tr.setOrigin(posr);
tr.setRotation(btQuaternion(quat[0], quat[1], quat[2], quat[3]));
col->setWorldTransform(tr);
col->setFriction(friction);
pWorld->addCollisionObject(col, 2, 1 + 2);
pMultiBody->getLink(i).m_collider = col;
}
}
class CommonExampleInterface* MultiBodyBaselineCreateFunc(struct CommonExampleOptions& options)
{
return new MultiBodyBaseline(options.m_guiHelper);
}

20
examples/MultiBodyBaseline/MultiBodyBaseline.h Normal file
View File

@@ -0,0 +1,20 @@
/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
This software is provided 'as-is', without any express or implied warranty.
In no event will the authors be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it freely,
subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
#ifndef _MULTIBODY_BASELINE_H
#define _MULTIBODY_BASELINE_H
class CommonExampleInterface* MultiBodyBaselineCreateFunc(struct CommonExampleOptions& options);
#endif //_MULTIBODY_BASELINE_H

4
examples/VolumetricDeformable/VolumetricDeformable.cpp
View File

@@ -77,8 +77,8 @@ public:
void stepSimulation(float deltaTime)
{
//use a smaller internal timestep, there are stability issues
float internalTimeStep = 1. / 480.f;
m_dynamicsWorld->stepSimulation(deltaTime, 8, internalTimeStep);
float internalTimeStep = 1. / 240.f;
m_dynamicsWorld->stepSimulation(deltaTime, 4, internalTimeStep);
}
void createStaticBox(const btVector3& halfEdge, const btVector3& translation)

4
src/BulletDynamics/Featherstone/btMultiBodyDynamicsWorld.cpp
View File

@@ -422,7 +422,11 @@ void btMultiBodyDynamicsWorld::forwardKinematics()
void btMultiBodyDynamicsWorld::solveConstraints(btContactSolverInfo& solverInfo)
{
solveExternalForces(solverInfo);
solveInternalConstraints(solverInfo);
}
void btMultiBodyDynamicsWorld::solveInternalConstraints(btContactSolverInfo& solverInfo)
{
/// solve all the constraints for this island
m_islandManager->buildAndProcessIslands(getCollisionWorld()->getDispatcher(), getCollisionWorld(), m_solverMultiBodyIslandCallback);

1
src/BulletDynamics/Featherstone/btMultiBodyDynamicsWorld.h
View File

@@ -113,6 +113,7 @@ public:
virtual void getAnalyticsData(btAlignedObjectArray<struct btSolverAnalyticsData>& m_islandAnalyticsData) const;
virtual void solveExternalForces(btContactSolverInfo& solverInfo);
virtual void solveInternalConstraints(btContactSolverInfo& solverInfo);
};
#endif //BT_MULTIBODY_DYNAMICS_WORLD_H

27
src/BulletSoftBody/btCGProjection.h
View File

@@ -21,11 +21,10 @@ struct DeformableContactConstraint
btAlignedObjectArray<btScalar> m_value;
// the magnitude of the total impulse the node applied to the rb in the normal direction in the cg solve
btAlignedObjectArray<btScalar> m_accumulated_normal_impulse;
btAlignedObjectArray<btMultiBodyJacobianData> m_normal_jacobian;
DeformableContactConstraint(const btSoftBody::RContact& rcontact, const btMultiBodyJacobianData& jacobian)
DeformableContactConstraint(const btSoftBody::RContact& rcontact)
{
append(rcontact, jacobian);
append(rcontact);
}
DeformableContactConstraint(const btVector3 dir)
@@ -34,8 +33,6 @@ struct DeformableContactConstraint
m_direction.push_back(dir);
m_value.push_back(0);
m_accumulated_normal_impulse.push_back(0);
btMultiBodyJacobianData j;
m_normal_jacobian.push_back(j);
}
DeformableContactConstraint()
@@ -44,17 +41,14 @@ struct DeformableContactConstraint
m_direction.push_back(btVector3(0,0,0));
m_value.push_back(0);
m_accumulated_normal_impulse.push_back(0);
btMultiBodyJacobianData j;
m_normal_jacobian.push_back(j);
}
void append(const btSoftBody::RContact& rcontact, const btMultiBodyJacobianData& jacobian)
void append(const btSoftBody::RContact& rcontact)
{
m_contact.push_back(&rcontact);
m_direction.push_back(rcontact.m_cti.m_normal);
m_value.push_back(0);
m_accumulated_normal_impulse.push_back(0);
m_normal_jacobian.push_back(jacobian);
}
~DeformableContactConstraint()
@@ -77,8 +71,6 @@ struct DeformableFrictionConstraint
btAlignedObjectArray<btVector3> m_direction_prev;
btAlignedObjectArray<bool> m_released; // whether the contact is released
btAlignedObjectArray<btMultiBodyJacobianData> m_complementary_jacobian;
btAlignedObjectArray<btVector3> m_complementaryDirection;
// the total impulse the node applied to the rb in the tangential direction in the cg solve
@@ -89,12 +81,6 @@ struct DeformableFrictionConstraint
append();
}
DeformableFrictionConstraint(const btVector3& complementaryDir, const btMultiBodyJacobianData& jacobian)
{
append();
addJacobian(complementaryDir, jacobian);
}
void append()
{
m_static.push_back(false);
@@ -112,13 +98,6 @@ struct DeformableFrictionConstraint
m_accumulated_tangent_impulse.push_back(btVector3(0,0,0));
m_released.push_back(false);
}
void addJacobian(const btVector3& complementaryDir, const btMultiBodyJacobianData& jacobian)
{
m_complementary_jacobian.push_back(jacobian);
m_complementaryDirection.push_back(complementaryDir);
}
};
class btCGProjection

488
src/BulletSoftBody/btContactProjection.cpp
View File

@@ -1,488 +0,0 @@
//
// btDeformableContactProjection.cpp
// BulletSoftBody
//
// Created by Xuchen Han on 7/4/19.
//
#include "btDeformableContactProjection.h"
#include "btDeformableRigidDynamicsWorld.h"
#include <algorithm>
static void findJacobian(const btMultiBodyLinkCollider* multibodyLinkCol,
btMultiBodyJacobianData& jacobianData,
const btVector3& contact_point,
const btVector3& dir)
{
const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
jacobianData.m_jacobians.resize(ndof);
jacobianData.m_deltaVelocitiesUnitImpulse.resize(ndof);
btScalar* jac = &jacobianData.m_jacobians[0];
multibodyLinkCol->m_multiBody->fillContactJacobianMultiDof(multibodyLinkCol->m_link, contact_point, dir, jac, jacobianData.scratch_r, jacobianData.scratch_v, jacobianData.scratch_m);
multibodyLinkCol->m_multiBody->calcAccelerationDeltasMultiDof(&jacobianData.m_jacobians[0], &jacobianData.m_deltaVelocitiesUnitImpulse[0], jacobianData.scratch_r, jacobianData.scratch_v);
}
static btVector3 generateUnitOrthogonalVector(const btVector3& u)
{
btScalar ux = u.getX();
btScalar uy = u.getY();
btScalar uz = u.getZ();
btScalar ax = std::abs(ux);
btScalar ay = std::abs(uy);
btScalar az = std::abs(uz);
btVector3 v;
if (ax <= ay && ax <= az)
v = btVector3(0, -uz, uy);
else if (ay <= ax && ay <= az)
v = btVector3(-uz, 0, ux);
else
v = btVector3(-uy, ux, 0);
v.normalize();
return v;
}
void btDeformableContactProjection::update()
{
///solve rigid body constraints
m_world->getSolverInfo().m_numIterations = 10;
m_world->btMultiBodyDynamicsWorld::solveConstraints(m_world->getSolverInfo());
// loop through constraints to set constrained values
for (auto& it : m_constraints)
{
btAlignedObjectArray<DeformableFrictionConstraint>& frictions = m_frictions[it.first];
btAlignedObjectArray<DeformableContactConstraint>& constraints = it.second;
for (int i = 0; i < constraints.size(); ++i)
{
DeformableContactConstraint& constraint = constraints[i];
DeformableFrictionConstraint& friction = frictions[i];
for (int j = 0; j < constraint.m_contact.size(); ++j)
{
if (constraint.m_contact[j] == nullptr)
{
// nothing needs to be done for dirichelet constraints
continue;
}
const btSoftBody::RContact* c = constraint.m_contact[j];
const btSoftBody::sCti& cti = c->m_cti;
// normal jacobian is precompute but tangent jacobian is not
const btMultiBodyJacobianData& jacobianData_normal = constraint.m_normal_jacobian[j];
const btMultiBodyJacobianData& jacobianData_complementary = friction.m_complementary_jacobian[j];
if (cti.m_colObj->hasContactResponse())
{
btVector3 va(0, 0, 0);
btRigidBody* rigidCol = 0;
btMultiBodyLinkCollider* multibodyLinkCol = 0;
const btScalar* deltaV_normal;
// grab the velocity of the rigid body
if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
{
rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
va = rigidCol ? (rigidCol->getVelocityInLocalPoint(c->m_c1)) * m_dt : btVector3(0, 0, 0);
}
else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
{
multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
if (multibodyLinkCol)
{
const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
const btScalar* jac_normal = &jacobianData_normal.m_jacobians[0];
deltaV_normal = &jacobianData_normal.m_deltaVelocitiesUnitImpulse[0];
// add in the normal component of the va
btScalar vel = 0.0;
for (int k = 0; k < ndof; ++k)
{
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[k] * jac_normal[k];
}
va = cti.m_normal * vel * m_dt;
// add in complementary direction of va
const btScalar* jac_complementary = &jacobianData_complementary.m_jacobians[0];
vel = 0.0;
for (int k = 0; k < ndof; ++k)
{
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[k] * jac_complementary[k];
}
va += friction.m_complementaryDirection[j] * vel * m_dt;
}
}
const btVector3 vb = c->m_node->m_v * m_dt;
const btVector3 vr = vb - va;
const btScalar dn = btDot(vr, cti.m_normal);
btVector3 impulse = c->m_c0 * vr;
const btVector3 impulse_normal = c->m_c0 * (cti.m_normal * dn);
const btVector3 impulse_tangent = impulse - impulse_normal;
// start friction handling
// copy old data
friction.m_impulse_prev[j] = friction.m_impulse[j];
friction.m_dv_prev[j] = friction.m_dv[j];
friction.m_static_prev[j] = friction.m_static[j];
// get the current tangent direction
btScalar local_tangent_norm = impulse_tangent.norm();
btVector3 local_tangent_dir = btVector3(0,0,0);
if (local_tangent_norm > SIMD_EPSILON)
local_tangent_dir = impulse_tangent.normalized();
// accumulated impulse on the rb in this and all prev cg iterations
constraint.m_accumulated_normal_impulse[j] += impulse_normal.dot(cti.m_normal);
const btScalar& accumulated_normal = constraint.m_accumulated_normal_impulse[j];
// the total tangential impulse required to stop sliding
btVector3 tangent = friction.m_accumulated_tangent_impulse[j] + impulse_tangent;
btScalar tangent_norm = tangent.norm();
if (accumulated_normal < 0)
{
friction.m_direction[j] = -local_tangent_dir;
// do not allow switching from static friction to dynamic friction
// it causes cg to explode
if (-accumulated_normal*c->m_c3 < tangent_norm && friction.m_static_prev[j] == false && friction.m_released[j] == false)
{
friction.m_static[j] = false;
friction.m_impulse[j] = -accumulated_normal*c->m_c3;
}
else
{
friction.m_static[j] = true;
friction.m_impulse[j] = tangent_norm;
}
}
else
{
friction.m_released[j] = true;
friction.m_static[j] = false;
friction.m_impulse[j] = 0;
friction.m_direction[j] = btVector3(0,0,0);
}
friction.m_dv[j] = friction.m_impulse[j] * c->m_c2/m_dt;
friction.m_accumulated_tangent_impulse[j] = -friction.m_impulse[j] * friction.m_direction[j];
// the incremental impulse applied to rb in the tangential direction
btVector3 incremental_tangent = (friction.m_impulse_prev[j] * friction.m_direction_prev[j])-(friction.m_impulse[j] * friction.m_direction[j]);
// TODO cleanup
if (1) // in the same CG solve, the set of constraits doesn't change
{
// c0 is the impulse matrix, c3 is 1 - the friction coefficient or 0, c4 is the contact hardness coefficient
// dv = new_impulse + accumulated velocity change in previous CG iterations
// so we have the invariant node->m_v = backupVelocity + dv;
btScalar dvn = -accumulated_normal * c->m_c2/m_dt;
// the following is equivalent
/*
btVector3 dv = -impulse_normal * c->m_c2/m_dt + c->m_node->m_v - backupVelocity[m_indices[c->m_node]];
btScalar dvn = dv.dot(cti.m_normal);
*/
constraint.m_value[j] = dvn;
// the incremental impulse:
// in the normal direction it's the normal component of "impulse"
// in the tangent direction it's the difference between the frictional impulse in the iteration and the previous iteration
impulse = impulse_normal + incremental_tangent;
if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
{
if (rigidCol)
rigidCol->applyImpulse(impulse, c->m_c1);
}
else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
{
if (multibodyLinkCol)
{
double multiplier = 1;
multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof(deltaV_normal, -impulse_normal.length() * multiplier);
if (incremental_tangent.norm() > SIMD_EPSILON)
{
btMultiBodyJacobianData jacobian_tangent;
btVector3 tangent = incremental_tangent.normalized();
findJacobian(multibodyLinkCol, jacobian_tangent, c->m_node->m_x, tangent);
const btScalar* deltaV_tangent = &jacobian_tangent.m_deltaVelocitiesUnitImpulse[0];
multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof(deltaV_tangent, incremental_tangent.length() * multiplier);
}
}
}
}
}
}
}
}
}
void btDeformableContactProjection::setConstraints()
{
// set Dirichlet constraint
for (int i = 0; i < m_softBodies.size(); ++i)
{
btSoftBody* psb = m_softBodies[i];
for (int j = 0; j < psb->m_nodes.size(); ++j)
{
if (psb->m_nodes[j].m_im == 0)
{
btAlignedObjectArray<DeformableContactConstraint> c;
c.push_back(DeformableContactConstraint(btVector3(1,0,0)));
c.push_back(DeformableContactConstraint(btVector3(0,1,0)));
c.push_back(DeformableContactConstraint(btVector3(0,0,1)));
m_constraints[&(psb->m_nodes[j])] = c;
btAlignedObjectArray<DeformableFrictionConstraint> f;
f.push_back(DeformableFrictionConstraint());
f.push_back(DeformableFrictionConstraint());
f.push_back(DeformableFrictionConstraint());
m_frictions[&(psb->m_nodes[j])] = f;
}
}
}
for (int i = 0; i < m_softBodies.size(); ++i)
{
btSoftBody* psb = m_softBodies[i];
btMultiBodyJacobianData jacobianData_normal;
btMultiBodyJacobianData jacobianData_complementary;
for (int j = 0; j < psb->m_rcontacts.size(); ++j)
{
const btSoftBody::RContact& c = psb->m_rcontacts[j];
// skip anchor points
if (c.m_node->m_im == 0)
{
continue;
}
const btSoftBody::sCti& cti = c.m_cti;
if (cti.m_colObj->hasContactResponse())
{
btVector3 va(0, 0, 0);
btRigidBody* rigidCol = 0;
btMultiBodyLinkCollider* multibodyLinkCol = 0;
// grab the velocity of the rigid body
if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
{
rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
va = rigidCol ? (rigidCol->getVelocityInLocalPoint(c.m_c1)) * m_dt : btVector3(0, 0, 0);
}
else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
{
multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
if (multibodyLinkCol)
{
findJacobian(multibodyLinkCol, jacobianData_normal, c.m_node->m_x, cti.m_normal);
btScalar vel = 0.0;
const btScalar* jac = &jacobianData_normal.m_jacobians[0];
const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
for (int j = 0; j < ndof; ++j)
{
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[j] * jac[j];
std::cout << multibodyLinkCol->m_multiBody->getVelocityVector()[j] << std::endl;
std::cout << jac[j] << std::endl;
}
va = cti.m_normal * vel * m_dt;
}
}
const btVector3 vb = c.m_node->m_v * m_dt;
const btVector3 vr = vb - va;
const btScalar dn = btDot(vr, cti.m_normal);
if (dn < SIMD_EPSILON)
{
// find complementary jacobian
btVector3 complementaryDirection;
if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
{
multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
if (multibodyLinkCol)
{
complementaryDirection = generateUnitOrthogonalVector(cti.m_normal);
findJacobian(multibodyLinkCol, jacobianData_complementary, c.m_node->m_x, complementaryDirection);
}
}
if (m_constraints.find(c.m_node) == m_constraints.end())
{
btAlignedObjectArray<DeformableContactConstraint> constraints;
constraints.push_back(DeformableContactConstraint(c, jacobianData_normal));
m_constraints[c.m_node] = constraints;
btAlignedObjectArray<DeformableFrictionConstraint> frictions;
frictions.push_back(DeformableFrictionConstraint(complementaryDirection, jacobianData_complementary));
m_frictions[c.m_node] = frictions;
}
else
{
// group colinear constraints into one
const btScalar angle_epsilon = 0.015192247; // less than 10 degree
bool merged = false;
btAlignedObjectArray<DeformableContactConstraint>& constraints = m_constraints[c.m_node];
btAlignedObjectArray<DeformableFrictionConstraint>& frictions = m_frictions[c.m_node];
for (int j = 0; j < constraints.size(); ++j)
{
const btAlignedObjectArray<btVector3>& dirs = constraints[j].m_direction;
btScalar dot_prod = dirs[0].dot(cti.m_normal);
if (std::abs(std::abs(dot_prod) - 1) < angle_epsilon)
{
// group the constraints
constraints[j].append(c, jacobianData_normal);
// push in an empty friction
frictions[j].append();
frictions[j].addJacobian(complementaryDirection, jacobianData_complementary);
merged = true;
break;
}
}
const int dim = 3;
// hard coded no more than 3 constraint directions
if (!merged && constraints.size() < dim)
{
constraints.push_back(DeformableContactConstraint(c, jacobianData_normal));
frictions.push_back(DeformableFrictionConstraint(complementaryDirection, jacobianData_complementary));
}
}
}
}
}
}
}
void btDeformableContactProjection::enforceConstraint(TVStack& x)
{
const int dim = 3;
for (auto& it : m_constraints)
{
const btAlignedObjectArray<DeformableContactConstraint>& constraints = it.second;
size_t i = m_indices[it.first];
const btAlignedObjectArray<DeformableFrictionConstraint>& frictions = m_frictions[it.first];
btAssert(constraints.size() <= dim);
btAssert(constraints.size() > 0);
if (constraints.size() == 1)
{
x[i] -= x[i].dot(constraints[0].m_direction[0]) * constraints[0].m_direction[0];
for (int j = 0; j < constraints[0].m_direction.size(); ++j)
x[i] += constraints[0].m_value[j] * constraints[0].m_direction[j];
}
else if (constraints.size() == 2)
{
btVector3 free_dir = btCross(constraints[0].m_direction[0], constraints[1].m_direction[0]);
btAssert(free_dir.norm() > SIMD_EPSILON)
free_dir.normalize();
x[i] = x[i].dot(free_dir) * free_dir;
for (int j = 0; j < constraints.size(); ++j)
{
for (int k = 0; k < constraints[j].m_direction.size(); ++k)
{
x[i] += constraints[j].m_value[k] * constraints[j].m_direction[k];
}
}
}
else
{
x[i].setZero();
for (int j = 0; j < constraints.size(); ++j)
{
for (int k = 0; k < constraints[j].m_direction.size(); ++k)
{
x[i] += constraints[j].m_value[k] * constraints[j].m_direction[k];
}
}
}
// apply friction if the node is not constrained in all directions
if (constraints.size() < 3)
{
for (int f = 0; f < frictions.size(); ++f)
{
const DeformableFrictionConstraint& friction= frictions[f];
for (int j = 0; j < friction.m_direction.size(); ++j)
{
// clear the old constraint
if (friction.m_static_prev[j] == true)
{
x[i] -= friction.m_direction_prev[j] * friction.m_dv_prev[j];
}
// add the new constraint
if (friction.m_static[j] == true)
{
x[i] += friction.m_direction[j] * friction.m_dv[j];
}
}
}
}
}
}
void btDeformableContactProjection::project(TVStack& x)
{
const int dim = 3;
for (auto& it : m_constraints)
{
const btAlignedObjectArray<DeformableContactConstraint>& constraints = it.second;
size_t i = m_indices[it.first];
btAlignedObjectArray<DeformableFrictionConstraint>& frictions = m_frictions[it.first];
btAssert(constraints.size() <= dim);
btAssert(constraints.size() > 0);
if (constraints.size() == 1)
{
x[i] -= x[i].dot(constraints[0].m_direction[0]) * constraints[0].m_direction[0];
}
else if (constraints.size() == 2)
{
btVector3 free_dir = btCross(constraints[0].m_direction[0], constraints[1].m_direction[0]);
btAssert(free_dir.norm() > SIMD_EPSILON)
free_dir.normalize();
x[i] = x[i].dot(free_dir) * free_dir;
}
else
x[i].setZero();
// apply friction if the node is not constrained in all directions
if (constraints.size() < 3)
{
bool has_static_constraint = false;
for (int f = 0; f < frictions.size(); ++f)
{
DeformableFrictionConstraint& friction= frictions[f];
for (int j = 0; j < friction.m_static.size(); ++j)
has_static_constraint = has_static_constraint || friction.m_static[j];
}
for (int f = 0; f < frictions.size(); ++f)
{
DeformableFrictionConstraint& friction= frictions[f];
for (int j = 0; j < friction.m_direction.size(); ++j)
{
// clear the old friction force
if (friction.m_static_prev[j] == false)
{
x[i] -= friction.m_direction_prev[j] * friction.m_impulse_prev[j];
}
// only add to the rhs if there is no static friction constraint on the node
if (friction.m_static[j] == false && !has_static_constraint)
{
x[i] += friction.m_direction[j] * friction.m_impulse[j];
}
}
}
}
}
}
void btDeformableContactProjection::reinitialize(bool nodeUpdated)
{
btCGProjection::reinitialize(nodeUpdated);
m_constraints.clear();
m_frictions.clear();
}

72
src/BulletSoftBody/btDeformableContactProjection.cpp
View File

@@ -45,7 +45,7 @@ void btDeformableContactProjection::update()
{
///solve rigid body constraints
m_world->getSolverInfo().m_numIterations = 10;
m_world->btMultiBodyDynamicsWorld::solveConstraints(m_world->getSolverInfo());
m_world->btMultiBodyDynamicsWorld::solveInternalConstraints(m_world->getSolverInfo());
// loop through constraints to set constrained values
for (auto& it : m_constraints)
@@ -66,10 +66,6 @@ void btDeformableContactProjection::update()
const btSoftBody::RContact* c = constraint.m_contact[j];
const btSoftBody::sCti& cti = c->m_cti;
// normal jacobian is precompute but tangent jacobian is not
const btMultiBodyJacobianData& jacobianData_normal = constraint.m_normal_jacobian[j];
const btMultiBodyJacobianData& jacobianData_complementary = friction.m_complementary_jacobian[j];
if (cti.m_colObj->hasContactResponse())
{
btVector3 va(0, 0, 0);
@@ -89,25 +85,31 @@ void btDeformableContactProjection::update()
if (multibodyLinkCol)
{
const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
const btScalar* jac_normal = &jacobianData_normal.m_jacobians[0];
deltaV_normal = &jacobianData_normal.m_deltaVelocitiesUnitImpulse[0];
const btScalar* J_n = &c->jacobianData_normal.m_jacobians[0];
const btScalar* J_t1 = &c->jacobianData_t1.m_jacobians[0];
const btScalar* J_t2 = &c->jacobianData_t2.m_jacobians[0];
deltaV_normal = &c->jacobianData_normal.m_deltaVelocitiesUnitImpulse[0];
// add in the normal component of the va
btScalar vel = 0.0;
for (int k = 0; k < ndof; ++k)
{
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[k] * jac_normal[k];
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[k] * J_n[k];
}
va = cti.m_normal * vel * m_dt;
// add in complementary direction of va
const btScalar* jac_complementary = &jacobianData_complementary.m_jacobians[0];
vel = 0.0;
for (int k = 0; k < ndof; ++k)
{
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[k] * jac_complementary[k];
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[k] * J_t1[k];
}
va += friction.m_complementaryDirection[j] * vel * m_dt;
va += c->t1 * vel * m_dt;
vel = 0.0;
for (int k = 0; k < ndof; ++k)
{
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[k] * J_t2[k];
}
va += c->t2 * vel * m_dt;
}
}
@@ -143,8 +145,6 @@ void btDeformableContactProjection::update()
friction.m_direction[j] = -local_tangent_dir;
// do not allow switching from static friction to dynamic friction
// it causes cg to explode
btScalar comp1 = -accumulated_normal*c->m_c3;
btScalar comp2 = tangent_norm;
if (-accumulated_normal*c->m_c3 < tangent_norm && friction.m_static_prev[j] == false && friction.m_released[j] == false)
{
friction.m_static[j] = false;
@@ -194,19 +194,15 @@ void btDeformableContactProjection::update()
}
else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
{
if (multibodyLinkCol)
{
double multiplier = 1;
multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof(deltaV_normal, -impulse_normal.length() * multiplier);
multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof(deltaV_normal, impulse.dot(cti.m_normal));
if (incremental_tangent.norm() > SIMD_EPSILON)
{
btMultiBodyJacobianData jacobian_tangent;
btVector3 tangent = incremental_tangent.normalized();
findJacobian(multibodyLinkCol, jacobian_tangent, c->m_node->m_x, tangent);
const btScalar* deltaV_tangent = &jacobian_tangent.m_deltaVelocitiesUnitImpulse[0];
multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof(deltaV_tangent, incremental_tangent.length() * multiplier);
const btScalar* deltaV_t1 = &c->jacobianData_t1.m_deltaVelocitiesUnitImpulse[0];
multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof(deltaV_t1, impulse.dot(c->t1));
const btScalar* deltaV_t2 = &c->jacobianData_t2.m_deltaVelocitiesUnitImpulse[0];
multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof(deltaV_t2, impulse.dot(c->t2));
}
}
}
@@ -274,15 +270,12 @@ void btDeformableContactProjection::setConstraints()
multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
if (multibodyLinkCol)
{
findJacobian(multibodyLinkCol, jacobianData_normal, c.m_node->m_x, cti.m_normal);
btScalar vel = 0.0;
const btScalar* jac = &jacobianData_normal.m_jacobians[0];
const btScalar* jac = &c.jacobianData_normal.m_jacobians[0];
const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
for (int j = 0; j < ndof; ++j)
{
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[j] * jac[j];
std::cout << multibodyLinkCol->m_multiBody->getVelocityVector()[j] << std::endl;
std::cout << jac[j] << std::endl;
}
va = cti.m_normal * vel * m_dt;
}
@@ -293,25 +286,13 @@ void btDeformableContactProjection::setConstraints()
const btScalar dn = btDot(vr, cti.m_normal);
if (dn < SIMD_EPSILON)
{
// find complementary jacobian
btVector3 complementaryDirection;
if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
{
multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
if (multibodyLinkCol)
{
complementaryDirection = generateUnitOrthogonalVector(cti.m_normal);
findJacobian(multibodyLinkCol, jacobianData_complementary, c.m_node->m_x, complementaryDirection);
}
}
if (m_constraints.find(c.m_node) == m_constraints.end())
{
btAlignedObjectArray<DeformableContactConstraint> constraints;
constraints.push_back(DeformableContactConstraint(c, jacobianData_normal));
constraints.push_back(DeformableContactConstraint(c));
m_constraints[c.m_node] = constraints;
btAlignedObjectArray<DeformableFrictionConstraint> frictions;
frictions.push_back(DeformableFrictionConstraint(complementaryDirection, jacobianData_complementary));
frictions.push_back(DeformableFrictionConstraint());
m_frictions[c.m_node] = frictions;
}
else
@@ -328,10 +309,9 @@ void btDeformableContactProjection::setConstraints()
if (std::abs(std::abs(dot_prod) - 1) < angle_epsilon)
{
// group the constraints
constraints[j].append(c, jacobianData_normal);
constraints[j].append(c);
// push in an empty friction
frictions[j].append();
frictions[j].addJacobian(complementaryDirection, jacobianData_complementary);
merged = true;
break;
}
@@ -340,8 +320,8 @@ void btDeformableContactProjection::setConstraints()
// hard coded no more than 3 constraint directions
if (!merged && constraints.size() < dim)
{
constraints.push_back(DeformableContactConstraint(c, jacobianData_normal));
frictions.push_back(DeformableFrictionConstraint(complementaryDirection, jacobianData_complementary));
constraints.push_back(DeformableContactConstraint(c));
frictions.push_back(DeformableFrictionConstraint());
}
}
}

2
src/BulletSoftBody/btDeformableContactProjection.h
View File

@@ -40,4 +40,4 @@ public:
virtual void reinitialize(bool nodeUpdated);
};
#endif /* btContactProjection_h */
#endif /* btDeformableContactProjection_h */

37
src/BulletSoftBody/btDeformableRigidDynamicsWorld.cpp
View File

@@ -69,6 +69,43 @@ void btDeformableRigidDynamicsWorld::positionCorrection(btScalar dt)
rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
va = rigidCol ? (rigidCol->getVelocityInLocalPoint(c->m_c1)): btVector3(0, 0, 0);
}
else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
{
btMultiBodyLinkCollider* multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
if (multibodyLinkCol)
{
const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
const btScalar* J_n = &c->jacobianData_normal.m_jacobians[0];
const btScalar* J_t1 = &c->jacobianData_t1.m_jacobians[0];
const btScalar* J_t2 = &c->jacobianData_t2.m_jacobians[0];
// add in the normal component of the va
btScalar vel = 0.0;
for (int k = 0; k < ndof; ++k)
{
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[k] * J_n[k];
}
va = cti.m_normal * vel;
vel = 0.0;
for (int k = 0; k < ndof; ++k)
{
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[k] * J_t1[k];
}
va += c->t1 * vel;
vel = 0.0;
for (int k = 0; k < ndof; ++k)
{
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[k] * J_t2[k];
}
va += c->t2 * vel;
}
}
else
{
// The object interacting with deformable node is not supported for position correction
btAssert(false);
}
if (cti.m_colObj->hasContactResponse())
{

10
src/BulletSoftBody/btSoftBody.h
View File

@@ -26,7 +26,8 @@ subject to the following restrictions:
#include "BulletCollision/CollisionDispatch/btCollisionCreateFunc.h"
#include "btSparseSDF.h"
#include "BulletCollision/BroadphaseCollision/btDbvt.h"
#include "BulletDynamics/Featherstone/btMultiBodyLinkCollider.h"
#include "BulletDynamics/Featherstone/btMultiBodyConstraint.h"
//#ifdef BT_USE_DOUBLE_PRECISION
//#define btRigidBodyData btRigidBodyDoubleData
//#define btRigidBodyDataName "btRigidBodyDoubleData"
@@ -300,6 +301,13 @@ public:
btScalar m_c2; // ima*dt
btScalar m_c3; // Friction
btScalar m_c4; // Hardness
// jacobians and unit impulse responses for multibody
btMultiBodyJacobianData jacobianData_normal;
btMultiBodyJacobianData jacobianData_t1;
btMultiBodyJacobianData jacobianData_t2;
btVector3 t1;
btVector3 t2;
};
/* SContact */
struct SContact

141
src/BulletSoftBody/btSoftBodyInternals.h
View File

@@ -25,7 +25,41 @@ subject to the following restrictions:
#include "BulletCollision/CollisionDispatch/btCollisionDispatcher.h"
#include "BulletCollision/CollisionShapes/btConvexInternalShape.h"
#include "BulletCollision/NarrowPhaseCollision/btGjkEpa2.h"
#include "BulletDynamics/Featherstone/btMultiBodyLinkCollider.h"
#include "BulletDynamics/Featherstone/btMultiBodyConstraint.h"
#include <string.h> //for memset
#include <iostream>
static void findJacobian(const btMultiBodyLinkCollider* multibodyLinkCol,
btMultiBodyJacobianData& jacobianData,
const btVector3& contact_point,
const btVector3& dir)
{
const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
jacobianData.m_jacobians.resize(ndof);
jacobianData.m_deltaVelocitiesUnitImpulse.resize(ndof);
btScalar* jac = &jacobianData.m_jacobians[0];
multibodyLinkCol->m_multiBody->fillContactJacobianMultiDof(multibodyLinkCol->m_link, contact_point, dir, jac, jacobianData.scratch_r, jacobianData.scratch_v, jacobianData.scratch_m);
multibodyLinkCol->m_multiBody->calcAccelerationDeltasMultiDof(&jacobianData.m_jacobians[0], &jacobianData.m_deltaVelocitiesUnitImpulse[0], jacobianData.scratch_r, jacobianData.scratch_v);
}
static btVector3 generateUnitOrthogonalVector(const btVector3& u)
{
btScalar ux = u.getX();
btScalar uy = u.getY();
btScalar uz = u.getZ();
btScalar ax = std::abs(ux);
btScalar ay = std::abs(uy);
btScalar az = std::abs(uz);
btVector3 v;
if (ax <= ay && ax <= az)
v = btVector3(0, -uz, uy);
else if (ay <= ax && ay <= az)
v = btVector3(-uz, 0, ux);
else
v = btVector3(-uy, ux, 0);
v.normalize();
return v;
}
//
// btSymMatrix
//
@@ -298,6 +332,46 @@ static inline btMatrix3x3 Diagonal(btScalar x)
m[2] = btVector3(0, 0, x);
return (m);
}
static inline btMatrix3x3 Diagonal(const btVector3& v)
{
btMatrix3x3 m;
m[0] = btVector3(v.getX(), 0, 0);
m[1] = btVector3(0, v.getY(), 0);
m[2] = btVector3(0, 0, v.getZ());
return (m);
}
static inline btScalar Dot(const btScalar* a,const btScalar* b, int ndof)
{
btScalar result = 0;
for (int i = 0; i < ndof; ++i)
result += a[i] * b[i];
return result;
}
static inline btMatrix3x3 OuterProduct(const btScalar* v1,const btScalar* v2,const btScalar* v3,
const btScalar* u1, const btScalar* u2, const btScalar* u3, int ndof)
{
btMatrix3x3 m;
btScalar a11 = Dot(v1,u1,ndof);
btScalar a12 = Dot(v1,u2,ndof);
btScalar a13 = Dot(v1,u3,ndof);
btScalar a21 = Dot(v2,u1,ndof);
btScalar a22 = Dot(v2,u2,ndof);
btScalar a23 = Dot(v2,u3,ndof);
btScalar a31 = Dot(v3,u1,ndof);
btScalar a32 = Dot(v3,u2,ndof);
btScalar a33 = Dot(v3,u3,ndof);
m[0] = btVector3(a11, a12, a13);
m[1] = btVector3(a21, a22, a23);
m[2] = btVector3(a31, a32, a33);
return (m);
}
//
static inline btMatrix3x3 Add(const btMatrix3x3& a,
const btMatrix3x3& b)
@@ -879,21 +953,68 @@ struct btSoftColliders
if (ms > 0)
{
psb->checkContact(m_colObj1Wrap, n.m_q, m, c.m_cti);
const btTransform& wtr = m_rigidBody ? m_rigidBody->getWorldTransform() : m_colObj1Wrap->getCollisionObject()->getWorldTransform();
static const btMatrix3x3 iwiStatic(0, 0, 0, 0, 0, 0, 0, 0, 0);
const btMatrix3x3& iwi = m_rigidBody ? m_rigidBody->getInvInertiaTensorWorld() : iwiStatic;
const btVector3 ra = n.m_q - wtr.getOrigin();
const btScalar fc = psb->m_cfg.kDF * m_colObj1Wrap->getCollisionObject()->getFriction();
auto& cti = c.m_cti;
c.m_node = &n;
c.m_c0 = ImpulseMatrix(psb->m_sst.sdt, ima, imb, iwi, ra);
c.m_c1 = ra;
const btScalar fc = psb->m_cfg.kDF * m_colObj1Wrap->getCollisionObject()->getFriction();
c.m_c2 = ima * psb->m_sst.sdt;
// c.m_c3 = fv.length2() < (dn * fc * dn * fc) ? 0 : 1 - fc;
c.m_c3 = fc;
c.m_c4 = m_colObj1Wrap->getCollisionObject()->isStaticOrKinematicObject() ? psb->m_cfg.kKHR : psb->m_cfg.kCHR;
if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
{
const btTransform& wtr = m_rigidBody ? m_rigidBody->getWorldTransform() : m_colObj1Wrap->getCollisionObject()->getWorldTransform();
static const btMatrix3x3 iwiStatic(0, 0, 0, 0, 0, 0, 0, 0, 0);
const btMatrix3x3& iwi = m_rigidBody ? m_rigidBody->getInvInertiaTensorWorld() : iwiStatic;
const btVector3 ra = n.m_q - wtr.getOrigin();
c.m_c0 = ImpulseMatrix(psb->m_sst.sdt, ima, imb, iwi, ra);
c.m_c1 = ra;
if (m_rigidBody)
m_rigidBody->activate();
}
else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
{
btMultiBodyLinkCollider* multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
if (multibodyLinkCol)
{
btVector3 normal = cti.m_normal;
btVector3 t1 = generateUnitOrthogonalVector(normal);
btVector3 t2 = btCross(normal, t1);
btMultiBodyJacobianData jacobianData_normal, jacobianData_t1, jacobianData_t2;
findJacobian(multibodyLinkCol, jacobianData_normal, c.m_node->m_q, normal);
findJacobian(multibodyLinkCol, jacobianData_t1, c.m_node->m_q, t1);
findJacobian(multibodyLinkCol, jacobianData_t2, c.m_node->m_q, t2);
btScalar* J_n = &jacobianData_normal.m_jacobians[0];
btScalar* J_t1 = &jacobianData_t1.m_jacobians[0];
btScalar* J_t2 = &jacobianData_t2.m_jacobians[0];
btScalar* u_n = &jacobianData_normal.m_deltaVelocitiesUnitImpulse[0];
btScalar* u_t1 = &jacobianData_t1.m_deltaVelocitiesUnitImpulse[0];
btScalar* u_t2 = &jacobianData_t2.m_deltaVelocitiesUnitImpulse[0];
btMatrix3x3 rot(normal, t1, t2); // world frame to local frame
const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
btVector3 u_dot_J(0,0,0);
for (int i = 0; i < ndof; ++i)
{
u_dot_J += btVector3(J_n[i] * u_n[i], J_t1[i] * u_t1[i], J_t2[i] * u_t2[i]);
}
btVector3 impulse_matrix_diag;
btScalar dt = psb->m_sst.sdt;
impulse_matrix_diag.setX(1/((u_dot_J.getX() + n.m_im) * dt));
impulse_matrix_diag.setY(1/((u_dot_J.getY() + n.m_im) * dt));
impulse_matrix_diag.setZ(1/((u_dot_J.getZ() + n.m_im) * dt));
btMatrix3x3 local_impulse_matrix = Diagonal(1/dt) * (Diagonal(n.m_im) + OuterProduct(J_n, J_t1, J_t2, u_n, u_t1, u_t2, ndof)).inverse();
c.m_c0 = rot.transpose() * local_impulse_matrix * rot;
c.jacobianData_normal = jacobianData_normal;
c.jacobianData_t1 = jacobianData_t1;
c.jacobianData_t2 = jacobianData_t2;
c.t1 = t1;
c.t2 = t2;
}
}
psb->m_rcontacts.push_back(c);
if (m_rigidBody)
m_rigidBody->activate();
}
}
}