tgWorldBulletPhysicsImpl.cpp

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/*
 * Copyright © 2012, United States Government, as represented by the
 * Administrator of the National Aeronautics and Space Administration.
 * All rights reserved.
 * 
 * The NASA Tensegrity Robotics Toolkit (NTRT) v1 platform is licensed
 * under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0.
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */


// This module
#include "tgWorldBulletPhysicsImpl.h"
// This application
#include "tgWorld.h"
#include "tgCast.h"
#include "terrain/tgBulletGround.h"
#include "terrain/tgEmptyGround.h"
// The Bullet Physics library
#include "BulletCollision/BroadphaseCollision/btBroadphaseInterface.h"
#include "BulletCollision/BroadphaseCollision/btDbvtBroadphase.h"
#include "BulletCollision/BroadphaseCollision/btAxisSweep3.h" // New broadphase
#include "BulletCollision/CollisionDispatch/btCollisionDispatcher.h"
#include "BulletCollision/CollisionDispatch/btDefaultCollisionConfiguration.h"
#include "BulletCollision/CollisionShapes/btBoxShape.h"
#include "BulletCollision/CollisionShapes/btBvhTriangleMeshShape.h"
#include "BulletCollision/CollisionShapes/btCompoundShape.h"
#include "BulletDynamics/Dynamics/btRigidBody.h"
#include "BulletDynamics/Dynamics/btDynamicsWorld.h"
#include "BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.h"
#include "BulletSoftBody/btSoftBodyRigidBodyCollisionConfiguration.h"
#include "BulletSoftBody/btSoftRigidDynamicsWorld.h"
#include "LinearMath/btDefaultMotionState.h"
#include "LinearMath/btScalar.h"
#include "LinearMath/btTransform.h"
#include "LinearMath/btVector3.h"
#include "LinearMath/btQuickprof.h"

// Ghost objects
#include "BulletCollision/CollisionDispatch/btGhostObject.h"
#include "BulletCollision/BroadphaseCollision/btOverlappingPairCache.h"

#define MCLP_SOLVER

#ifdef MLCP_SOLVER

#include "BulletDynamics/MLCPSolvers/btDantzigSolver.h"
#include "BulletDynamics/MLCPSolvers/btSolveProjectedGaussSeidel.h"
#include "BulletDynamics/MLCPSolvers/btMLCPSolver.h"

#endif //MLCP_SOLVER

class IntermediateBuildProducts
{
    public:
        IntermediateBuildProducts(double worldSize) : 
            corner1 (-worldSize,-worldSize, -worldSize),
            corner2 (worldSize, worldSize, worldSize),
            dispatcher(&collisionConfiguration),
            ghostCallback(),
#ifndef   MLCP_SOLVER       
                #if (1) // More acc broadphase - remeber the comma (consider doing ifndef)
                                                                broadphase(corner1, corner2, 16384)
                #endif // Broadphase
#else
                                                broadphase(corner1, corner2, 16384),
                                                solver(&mlcp)
#endif //MLCP_SOLVER  
                                                
  {
                  broadphase.getOverlappingPairCache()->setInternalGhostPairCallback(&ghostCallback);
  }
  const btVector3 corner1;
  const btVector3 corner2;
  btSoftBodyRigidBodyCollisionConfiguration collisionConfiguration;
  btCollisionDispatcher dispatcher;
  btGhostPairCallback ghostCallback;
#if (0) // Default broadphase
        btDbvtBroadphase broadphase;
#else
        // More accurate broadphase:
        btAxisSweep3 broadphase;
#endif

#ifdef MLCP_SOLVER
                                //btDantzigSolver mlcp;
                                btSolveProjectedGaussSeidel mlcp;
                                btMLCPSolver solver;
#else
                                btSequentialImpulseConstraintSolver solver;
#endif
                
};

tgWorldBulletPhysicsImpl::tgWorldBulletPhysicsImpl(const tgWorld::Config& config,
        tgBulletGround* ground) :
    tgWorldImpl(config, ground),
    m_pIntermediateBuildProducts(new IntermediateBuildProducts(config.worldSize)),
    m_pDynamicsWorld(createDynamicsWorld())
{

    // Gravitational acceleration is down on the Y axis
    const btVector3 gravityVector(0, -config.gravity, 0);
    m_pDynamicsWorld->setGravity(gravityVector);
                
                if (!tgCast::cast<tgBulletGround, tgEmptyGround>(ground) && ground != NULL)
                {
                                m_pDynamicsWorld->addRigidBody(ground->getGroundRigidBody());
                }
                
                /*
                 * These are lines from the old BasicLearningApp.cpp that we aren't using.
                 * http://bulletphysics.org/mediawiki-1.5.8/index.php/BtContactSolverInfo
                 */
    #if (0) 
                                // Split impulse does not appear to apply to MLCP solver
        m_pDynamicsWorld->getSolverInfo().m_splitImpulse = true;
        m_pDynamicsWorld->getSolverInfo().m_splitImpulsePenetrationThreshold = -0.02;
        
        // Default is 10 - increases runtime but decreases odds of penetration
        // Makes tetraspine sine waves more accurate and static test less accurate
        m_pDynamicsWorld->getSolverInfo().m_numIterations = 20;
    #endif      
    
    // Postcondition
    assert(invariant());
}

tgWorldBulletPhysicsImpl::~tgWorldBulletPhysicsImpl()
{
    // Delete all the collision objects. The dynamics world must exist.
    // Delete in reverse order of creation.
    const size_t nco = m_pDynamicsWorld->getNumCollisionObjects();
    btCollisionObjectArray& oa = m_pDynamicsWorld->getCollisionObjectArray();
    for (int i = nco - 1; i >= 0; --i)
    {
        btCollisionObject * const pCollisionObject = oa[i];

        // If the collision object is a rigid body, delete its motion state
        const btRigidBody* const pRigidBody =
            btRigidBody::upcast(pCollisionObject);
        if (pRigidBody)
        {
            delete pRigidBody->getMotionState();
        }

        // Remove the collision object from the dynamics world
        m_pDynamicsWorld->removeCollisionObject(pCollisionObject);
        // Delete the collision object
        delete pCollisionObject;
    }
    // All collision objects have been removed and deleted
    assert(m_pDynamicsWorld->getNumCollisionObjects() == 0);

    // Delete all the collision shapes. This can be done at any time.
    const size_t ncs = m_collisionShapes.size();
    
    for (size_t i = 0; i < ncs; ++i) { delete m_collisionShapes[i]; }

    delete m_pDynamicsWorld;

    // Delete the intermediate build products, which are now orphaned
    delete m_pIntermediateBuildProducts;
}

btDynamicsWorld* tgWorldBulletPhysicsImpl::createDynamicsWorld() const
{    
  btSoftRigidDynamicsWorld* const result =
    new btSoftRigidDynamicsWorld(&m_pIntermediateBuildProducts->dispatcher,
                 &m_pIntermediateBuildProducts->broadphase,
                 &m_pIntermediateBuildProducts->solver, 
                 &m_pIntermediateBuildProducts->collisionConfiguration);
#ifdef MLCPSOLVER               
                                result ->getSolverInfo().m_minimumSolverBatchSize = 1;//for direct solver it is better to have a small A matrix
#endif          
  return result;
}

void tgWorldBulletPhysicsImpl::step(double dt)
{
    // Precondition
    assert(dt > 0.0);

    const btScalar timeStep = dt;
    const int maxSubSteps = 1;
    const btScalar fixedTimeStep = dt;
    m_pDynamicsWorld->stepSimulation(timeStep, maxSubSteps, fixedTimeStep);

    // Postcondition
    assert(invariant());
}

void tgWorldBulletPhysicsImpl::addCollisionShape(btCollisionShape* pShape)
{
#ifndef BT_NO_PROFILE 
    BT_PROFILE("addCollisionShape");
#endif //BT_NO_PROFILE          
                
    if (pShape)
    {
        m_collisionShapes.push_back(pShape);
    }

      // Postcondition
      assert(invariant());
}

void tgWorldBulletPhysicsImpl::deleteCollisionShape(btCollisionShape* pShape)
{
#ifndef BT_NO_PROFILE 
    BT_PROFILE("deleteCollisionShape");
#endif //BT_NO_PROFILE
                
    if (pShape)
    {
                                btCompoundShape* cShape = tgCast::cast<btCollisionShape, btCompoundShape>(pShape);
                                if (cShape)
                                {
                                                std::size_t n = cShape->getNumChildShapes();
                                                for( std::size_t i = 0; i < n; i++)
                                                {
                                                                deleteCollisionShape(cShape->getChildShape(i));
                                                }
                                }
                                m_collisionShapes.remove(pShape);
        delete pShape;
    }

      // Postcondition
      assert(invariant());
}

bool tgWorldBulletPhysicsImpl::invariant() const
{
    return (m_pDynamicsWorld != 0);
}