output not shown with bullet physics library

[Laxmi]

I have tried to run the code with bullet physics library without using cmake and have been following this
http://dementedvice.wordpress.com/2013/ ... udio-2012/

everything went well with no errors but when I run it it shows no any output. how to see the output of the program???

#include "stdafx.h"
#include "btBulletDynamicsCommon.h"
int _tmain(int argc, _TCHAR* argv[]){
btBoxShape * box = new btBoxShape(btVector3(1,1,1));
delete box;
return 0;
}

[xexuxjy]

I'm not sure what you're expecting to see from that example? - you're creating and deleting a collision shape, thats all. Theres no code to setup a physics world, add objects or step the simulation. Looking at that example web page I think they're just testing for general compilation errors rather than anything more meaningful.
You'd be better off looking at one of the demo programs and looking at how it runs it's processing loop.

[bwelch]

Follow this tutorial. It'll get you up and running adding shapes and seeing things move about.

https://www.youtube.com/watch?v=wbu5MdsFYko

[Laxmi]

I'm not sure what you're expecting to see from that example? - you're creating and deleting a collision shape, thats all. Theres no code to setup a physics world, add objects or step the simulation. Looking at that example web page I think they're just testing for general compilation errors rather than anything more meaningful.
You'd be better off looking at one of the demo programs and looking at how it runs it's processing loop.

even I tried with the code of Helloworld from this site
http://bulletphysics.org/mediawiki-1.5. ... ello_World
but the output window blinks and disappears.

[xexuxjy]

how many simulation loops did you go through?

what you should be doing is:

Create physics world (DiscreteDynamicsWorld, Dispatcher, Broadphase)

create your collision shapes and rigid bodies.

add them to the world.

loop , stepping the simulation until you've reached the number of steps you want, or a key press stops the simulation, or whatever.

cleanup the world

they key point though is that by default you will not _see_ anything on the screen. if you want to see if somethings happening you could get the positions of your rigid bodies and print them out to the screen, or you could hook up a DebugDraw system so you can visualise things, but by default 'all' bullet will be doing is updating the states of the objects.

[bwelch]

even I tried with the code of Helloworld from this site
http://bulletphysics.org/mediawiki-1.5. ... ello_World
but the output window blinks and disappears.

Try putting

Code: Select all

int x;
std::cin >> x;

somewhere after the output is supposed to display. It'll prevent the output window from disappearing on you.

[Laxmi]

how many simulation loops did you go through?

what you should be doing is:

Create physics world (DiscreteDynamicsWorld, Dispatcher, Broadphase)

create your collision shapes and rigid bodies.

add them to the world.

loop , stepping the simulation until you've reached the number of steps you want, or a key press stops the simulation, or whatever.

cleanup the world

they key point though is that by default you will not _see_ anything on the screen. if you want to see if somethings happening you could get the positions of your rigid bodies and print them out to the screen, or you could hook up a DebugDraw system so you can visualise things, but by default 'all' bullet will be doing is updating the states of the objects.

Thanks for your answer. I am using visual studio 2010 for running the program. here is the actual code

Code: Select all

///-----includes_start-----
#include "stdafx.h"
#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-----
}

In the output console I see the coordinates. however how can I display the object in the new windows in visual studio. Do I need to create windows form application in visual studio????

[Basroil]

In the output console I see the coordinates. however how can I display the object in the new windows in visual studio. Do I need to create windows form application in visual studio????

Display what objects, bullet is a physics library, not a graphics one

What you need is to just build the demos first and see how they work, there's also a simple OGL based rendering system set up for demos you can use too.

[Laxmi]

In the output console I see the coordinates. however how can I display the object in the new windows in visual studio. Do I need to create windows form application in visual studio????

Display what objects, bullet is a physics library, not a graphics one

What you need is to just build the demos first and see how they work, there's also a simple OGL based rendering system set up for demos you can use too.

I have almost build all the demos in the folder and it displays some figurative display object like box ,sphere ,floor. How can I acheive such ?? Do I need to integrate opengl with bullet to render the phsical objects??

[c6burns]

You will indeed need some kind of graphics API in order to render graphics. I use Ogre, but there are many choices out there including creating your own renderer using OpenGL or DirectX

[Basroil]

I have almost build all the demos in the folder and it displays some figurative display object like box ,sphere ,floor. How can I acheive such ?? Do I need to integrate opengl with bullet to render the phsical objects??

If you have problems adapting the demos I think the issue is deeper than just using bullet. I would suggest putting your project on hold until you learn the basics of game engine design, even an overview would help vastly more than people handing you code to use. The demos have everything you need to use bullet in code form, now you just need to learn how to read code and analyze it.

Just remember, bullet itself is a computation library, it calculates things to give you numbers, it's up to your other code to do something with those numbers.