BulletPhysicsBasic.cpp

///-----includes_start-----
#include "btBulletDynamicsCommon.h"
#include <stdio.h>

/// This is a Hello World program for running a basic Bullet physics simulation

int main(int argc, char** argv)
{
	///-----includes_end-----

	int i;
	///-----initialization_start-----

	///collision configuration contains default setup for memory, collision setup. Advanced users can create their own configuration.
	btDefaultCollisionConfiguration* collisionConfiguration = new btDefaultCollisionConfiguration();

	///use the default collision dispatcher. For parallel processing you can use a diffent dispatcher (see Extras/BulletMultiThreaded)
	btCollisionDispatcher* dispatcher = new	btCollisionDispatcher(collisionConfiguration);

	///btDbvtBroadphase is a good general purpose broadphase. You can also try out btAxis3Sweep.
	btBroadphaseInterface* overlappingPairCache = new btDbvtBroadphase();

	///the default constraint solver. For parallel processing you can use a different solver (see Extras/BulletMultiThreaded)
	btSequentialImpulseConstraintSolver* solver = new btSequentialImpulseConstraintSolver;

	btDiscreteDynamicsWorld* dynamicsWorld = new btDiscreteDynamicsWorld(dispatcher,overlappingPairCache,solver,collisionConfiguration);

	dynamicsWorld->setGravity(btVector3(0,-10,0));

	///-----initialization_end-----

	///create a few basic rigid bodies
	btCollisionShape* groundShape = new btBoxShape(btVector3(btScalar(50.),btScalar(50.),btScalar(50.)));

	//keep track of the shapes, we release memory at exit.
	//make sure to re-use collision shapes among rigid bodies whenever possible!
	btAlignedObjectArray<btCollisionShape*> collisionShapes;

	collisionShapes.push_back(groundShape);

	btTransform groundTransform;
	groundTransform.setIdentity();
	groundTransform.setOrigin(btVector3(0,-56,0));

	{
		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);

		//add the body to the dynamics world
		dynamicsWorld->addRigidBody(body);
	}


	{
		//create a dynamic rigidbody

		//btCollisionShape* colShape = new btBoxShape(btVector3(1,1,1));
		btCollisionShape* colShape = new btSphereShape(btScalar(1.));
		collisionShapes.push_back(colShape);

		/// Create Dynamic Objects
		btTransform startTransform;
		startTransform.setIdentity();

		btScalar	mass(1.f);

		//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)
			colShape->calculateLocalInertia(mass,localInertia);

			startTransform.setOrigin(btVector3(2,10,0));
		
			//using motionstate is recommended, it provides interpolation capabilities, and only synchronizes 'active' objects
			btDefaultMotionState* myMotionState = new btDefaultMotionState(startTransform);
			btRigidBody::btRigidBodyConstructionInfo rbInfo(mass,myMotionState,colShape,localInertia);
			btRigidBody* body = new btRigidBody(rbInfo);

			dynamicsWorld->addRigidBody(body);
	}



/// Do some simulation


	///-----stepsimulation_start-----
	for (i=0;i<100;i++)
	{
		dynamicsWorld->stepSimulation(1.f/60.f,10);
		
		//print positions of all objects
		for (int j=dynamicsWorld->getNumCollisionObjects()-1; j>=0 ;j--)
		{
			btCollisionObject* obj = dynamicsWorld->getCollisionObjectArray()[j];
			btRigidBody* body = btRigidBody::upcast(obj);
			if (body && body->getMotionState())
			{
				btTransform trans;
				body->getMotionState()->getWorldTransform(trans);
				printf("world pos = %f,%f,%f\n",float(trans.getOrigin().getX()),float(trans.getOrigin().getY()),float(trans.getOrigin().getZ()));
			}
		}
	}

	///-----stepsimulation_end-----

	//cleanup in the reverse order of creation/initialization
	
	///-----cleanup_start-----

	//remove the rigidbodies from the dynamics world and delete them
	for (i=dynamicsWorld->getNumCollisionObjects()-1; i>=0 ;i--)
	{
		btCollisionObject* obj = dynamicsWorld->getCollisionObjectArray()[i];
		btRigidBody* body = btRigidBody::upcast(obj);
		if (body && body->getMotionState())
		{
			delete body->getMotionState();
		}
		dynamicsWorld->removeCollisionObject( obj );
		delete obj;
	}

	//delete collision shapes
	for (int j=0;j<collisionShapes.size();j++)
	{
		btCollisionShape* shape = collisionShapes[j];
		collisionShapes[j] = 0;
		delete shape;
	}

	//delete dynamics world
	delete dynamicsWorld;

	//delete solver
	delete solver;

	//delete broadphase
	delete overlappingPairCache;

	//delete dispatcher
	delete dispatcher;

	delete collisionConfiguration;

	//next line is optional: it will be cleared by the destructor when the array goes out of scope
	collisionShapes.clear();

	///-----cleanup_end-----
}