bullet3/examples/DeformableDemo/MultibodyClothAnchor.cpp

/*
 Bullet Continuous Collision Detection and Physics Library
 Copyright (c) 2019 Google Inc. http://bulletphysics.org
 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.
 */
#include "MultibodyClothAnchor.h"
///btBulletDynamicsCommon.h is the main Bullet include file, contains most common include files.
#include "btBulletDynamicsCommon.h"
#include "BulletSoftBody/btDeformableMultiBodyDynamicsWorld.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/CommonDeformableBodyBase.h"
#include "../Utils/b3ResourcePath.h"

///The MultibodyClothAnchor shows contact between deformable objects and rigid objects.
class MultibodyClothAnchor : public CommonDeformableBodyBase
{
public:
    MultibodyClothAnchor(struct GUIHelperInterface* helper)
    : CommonDeformableBodyBase(helper)
    {
    }
    virtual ~MultibodyClothAnchor()
    {
    }
    void initPhysics();
    
    void exitPhysics();
    
    void resetCamera()
    {
        float dist = 20;
        float pitch = -45;
        float yaw = 100;
        float targetPos[3] = {0, -3, 0};
        m_guiHelper->resetCamera(dist, yaw, pitch, targetPos[0], targetPos[1], targetPos[2]);
    }
    
    void stepSimulation(float deltaTime)
    {
        //use a smaller internal timestep, there are stability issues
        float internalTimeStep = 1. / 240.f;
        m_dynamicsWorld->stepSimulation(deltaTime, 4, internalTimeStep);
    }
    
    virtual void renderScene()
    {
        CommonDeformableBodyBase::renderScene();
        btDeformableMultiBodyDynamicsWorld* deformableWorld = getDeformableDynamicsWorld();
        
        for (int i = 0; i < deformableWorld->getSoftBodyArray().size(); i++)
        {
            btSoftBody* psb = (btSoftBody*)deformableWorld->getSoftBodyArray()[i];
            //if (softWorld->getDebugDrawer() && !(softWorld->getDebugDrawer()->getDebugMode() & (btIDebugDraw::DBG_DrawWireframe)))
            {
                btSoftBodyHelpers::DrawFrame(psb, deformableWorld->getDebugDrawer());
				btSoftBodyHelpers::Draw(psb, deformableWorld->getDebugDrawer(), fDrawFlags::Faces);// deformableWorld->getDrawFlags());
            }
        }
    }
    
    btMultiBody* createMultiBody(class btMultiBodyDynamicsWorld* world, int numLinks, const btVector3& basePosition, const btVector3& baseHalfExtents, const btVector3& linkHalfExtents, bool spherical = false, bool floating = false);
    
    void addColliders(btMultiBody* pMultiBody, btMultiBodyDynamicsWorld* pWorld, const btVector3& baseHalfExtents, const btVector3& linkHalfExtents);
};

void MultibodyClothAnchor::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();
    btDeformableBodySolver* deformableBodySolver = new btDeformableBodySolver();
    
    ///the default constraint solver. For parallel processing you can use a different solver (see Extras/BulletMultiThreaded)
    btDeformableMultiBodyConstraintSolver* sol = new btDeformableMultiBodyConstraintSolver();
    sol->setDeformableSolver(deformableBodySolver);
    m_solver = sol;
    
    m_dynamicsWorld = new btDeformableMultiBodyDynamicsWorld(m_dispatcher, m_broadphase, sol, m_collisionConfiguration, deformableBodySolver);
    //    deformableBodySolver->setWorld(getDeformableDynamicsWorld());
    //    m_dynamicsWorld->getSolverInfo().m_singleAxisDeformableThreshold = 0.f;//faster but lower quality
    btVector3 gravity = btVector3(0, -20, 0);
    m_dynamicsWorld->setGravity(gravity);
    getDeformableDynamicsWorld()->getWorldInfo().m_gravity = gravity;
    
    //    getDeformableDynamicsWorld()->before_solver_callbacks.push_back(dynamics);
    m_guiHelper->createPhysicsDebugDrawer(m_dynamicsWorld);
    
    {
        ///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, -35, 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(1);
        
        //add the ground to the dynamics world
        m_dynamicsWorld->addRigidBody(body,1,1+2);
    }
    
    // create a piece of cloth
    {
        const btScalar s = 4;
        const btScalar h = 6;
        const int r = 9;
        btSoftBody* psb = btSoftBodyHelpers::CreatePatch(getDeformableDynamicsWorld()->getWorldInfo(), btVector3(-s, h, -s),
                                                         btVector3(+s, h, -s),
                                                         btVector3(-s, h, +s),
                                                         btVector3(+s, h, +s), r, r, 4 + 8, true);
        psb->getCollisionShape()->setMargin(0.1);
        psb->generateBendingConstraints(2);
        psb->setTotalMass(1);
        psb->m_cfg.kKHR = 1; // collision hardness with kinematic objects
        psb->m_cfg.kCHR = 1; // collision hardness with rigid body
        psb->m_cfg.kDF = 2;
        psb->m_cfg.collisions = btSoftBody::fCollision::SDF_RD;
        getDeformableDynamicsWorld()->addSoftBody(psb);
        
        btDeformableMassSpringForce* mass_spring = new btDeformableMassSpringForce(30,1, true);
        getDeformableDynamicsWorld()->addForce(psb, mass_spring);
        m_forces.push_back(mass_spring);
        
        btDeformableGravityForce* gravity_force =  new btDeformableGravityForce(gravity);
        getDeformableDynamicsWorld()->addForce(psb, gravity_force);
        m_forces.push_back(gravity_force);
        
        bool damping = true;
        bool gyro = false;
        int numLinks = 5;
        bool spherical = false;  //set it ot false -to use 1DoF hinges instead of 3DoF sphericals
        bool canSleep = false;
        bool selfCollide = true;
        btVector3 linkHalfExtents(1.5, .5, .5);
        btVector3 baseHalfExtents(1.5, .5, .5);
        
        btMultiBody* mbC = createMultiBody(getDeformableDynamicsWorld(), numLinks, btVector3(s+3.5f, h, -s-0.6f), linkHalfExtents, baseHalfExtents, spherical, true);
        
        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(mbC, getDeformableDynamicsWorld(), baseHalfExtents, linkHalfExtents);

        // quick hack: advance time to populate the variables in multibody
        m_dynamicsWorld->stepSimulation(SIMD_EPSILON, 0);
        btAlignedObjectArray<btQuaternion> scratch_q;
        btAlignedObjectArray<btVector3> scratch_m;
        mbC->forwardKinematics(scratch_q, scratch_m);
        psb->appendDeformableAnchor(0, mbC->getLink(3).m_collider);
        psb->appendDeformableAnchor(r - 1, mbC->getLink(0).m_collider);
    }
    getDeformableDynamicsWorld()->setImplicit(false);
    getDeformableDynamicsWorld()->setLineSearch(false);
    m_guiHelper->autogenerateGraphicsObjects(m_dynamicsWorld);
}

void MultibodyClothAnchor::exitPhysics()
{
    //cleanup in the reverse order of creation/initialization
    removePickingConstraint();
    //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 forces
    for (int j = 0; j < m_forces.size(); j++)
    {
        btDeformableLagrangianForce* force = m_forces[j];
        delete force;
    }
    m_forces.clear();
    //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;
}

btMultiBody* MultibodyClothAnchor::createMultiBody(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 = 1.f;

    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);

    //init the links
    btVector3 hingeJointAxis(0, 1, 0);
    float linkMass = 1.f;
    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(-linkHalfExtents[0] * 2.f, 0, 0);                      //par body's COM to cur body's COM offset
    btVector3 currentPivotToCurrentCom(-linkHalfExtents[0], 0, 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->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 MultibodyClothAnchor::addColliders(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();
    
    {
        btScalar quat[4] = {-world_to_local[0].x(), -world_to_local[0].y(), -world_to_local[0].z(), world_to_local[0].w()};

        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(1);
        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];
        
        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(1);
        pWorld->addCollisionObject(col, 2, 1+2);
        pMultiBody->getLink(i).m_collider = col;
    }
}

class CommonExampleInterface* MultibodyClothAnchorCreateFunc(struct CommonExampleOptions& options)
{
    return new MultibodyClothAnchor(options.m_guiHelper);
}