Irrlicht Engine • (C++) Simple Bullet Physics Class/Manager

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(C++) Simple Bullet Physics Class/Manager

Posted: Fri Jul 02, 2010 7:15 pm

by Buck1000

Well, I thought I might finally contribute to the Irrlicht community by sharing some of my code

Below is a class that I have created for my own project, and that I have been using for Bullet physics integration. Its by no means a wrapper, as it only gets the basic necessities for physics up and running. I myself use it in other functions to control my physics world.

In its original state, it required pointers to some other classes that are specific to my project, so I did a bit of editing to remove that requirement. I have however not tested the edited version, but I believe it should work fine. If there are any issues, I'll be happy to fix them

Now, to give credit where it is due -> I borrowed code from several sources to create this, although I have forgotten who most of them are

Some of it is from various Bullet-Irrlicht tutorials, other pieces are either taken from, or inspired by irrBullet.

Its meant for those that want to quickly implement Bullet into their projects, but don't want a full wrapper.

So, first off, some screenies ->

A standard box stack

The same stack after an explosion ->

And, the resulting rubble after an "attraction"

->

So, here is CPhysics.h --

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#ifndef _CPHYSICS_H
#define _CPHYSICS_H

#include <btBulletCollisionCommon.h>
#include <btBulletDynamicsCommon.h>
#include <BulletCollision\CollisionDispatch\btGhostObject.h>

class CPhysics
{
    public:
    CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, btVector3 Gravity, IAnimatedMeshSceneNode* Map);
    void Update();
    bool UpdateRender(btRigidBody* TObject);
    btTriangleMesh* ConvertIrrMeshToBulletTriangleMesh(IMesh* pMesh,const vector3df& scaling);
    void QuaternionToEuler(const btQuaternion &TQuat, btVector3 &TEuler);
    void getConvexHull(IMesh *collMesh, btConvexHullShape *hullShape, IAnimatedMeshSceneNode* node);
    list<btRigidBody *> getObjectList();

    btRigidBody* CreateBox(const btVector3 &TPosition, const vector3df &TScale, btScalar TMass);
    btRigidBody* loadConvex(std::string filename, const btVector3 &TPosition, const vector3df &TScale, btScalar TMass);

    btDiscreteDynamicsWorld* getWorld();

    private:
    ISceneManager* smgr;
    IVideoDriver* driver;
    ITimer* Timer;
    btDiscreteDynamicsWorld* World;
    list<btRigidBody *> Objects;
    btVector3 Gravity;
    u32 TimeStamp;
    u32 DeltaTime;
};

#endif

And CPhysics.cpp--

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#include "CPhysics.h"

CPhysics::CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, btVector3 Gravity, IAnimatedMeshSceneNode* Map)
{
   btDefaultCollisionConfiguration* CollisionConfiguration = new btDefaultCollisionConfiguration();
	btBroadphaseInterface* BroadPhase = new btAxisSweep3(btVector3(-100000, -100000, -100000), btVector3(100000, 100000, 100000));
	BroadPhase->getOverlappingPairCache()->setInternalGhostPairCallback(new btGhostPairCallback());
	btCollisionDispatcher* Dispatcher = new btCollisionDispatcher(CollisionConfiguration);
	btSequentialImpulseConstraintSolver* Solver = new btSequentialImpulseConstraintSolver();
	CPhysics::World = new btDiscreteDynamicsWorld(Dispatcher, BroadPhase, Solver, CollisionConfiguration);
	CPhysics::World->setGravity(Gravity);
	CPhysics::Gravity = Gravity;
	CPhysics::smgr = smgr;
	CPhysics::driver = driver;
	CPhysics::Timer = Timer;
	CPhysics::TimeStamp = Timer->getTime();
	CPhysics::DeltaTime = 0;

	btTriangleMesh* indexVertexArrays = CPhysics::ConvertIrrMeshToBulletTriangleMesh(Map->getMesh(),Map->getMesh()->getScale());
	btBvhTriangleMeshShape* trimeshShape = new btBvhTriangleMeshShape(indexVertexArrays, true);

	btQuaternion quat;
	quat.setEulerZYX(0,0,0);
	btTransform Transform2;
	Transform2.setIdentity();
	Transform2.setOrigin(btVector3(0,0,0));
	Transform2.setRotation(quat);

	btDefaultMotionState *MotionState2 = new btDefaultMotionState(Transform2);

	btRigidBody *RigidBody = new btRigidBody(0, MotionState2, trimeshShape);

	RigidBody->setUserPointer((void *)(Map->getNode()));

	CPhysics::World->addRigidBody(RigidBody);
	CPhysics::Objects.push_back(RigidBody);

	RigidBody->setCollisionFlags(btCollisionObject::CF_STATIC_OBJECT);
}

void CPhysics::Update()
{
    CPhysics::DeltaTime = CPhysics::Timer->getTime() - CPhysics::TimeStamp;
    CPhysics::TimeStamp = CPhysics::Timer->getTime();
    CPhysics::World->stepSimulation(CPhysics::DeltaTime * 0.001f, 2);
    for(list<btRigidBody *>::Iterator Iterator = CPhysics::Objects.begin(); Iterator != CPhysics::Objects.end();)
        if(!CPhysics::UpdateRender(*Iterator))
        {
            Iterator = CPhysics::Objects.erase(Iterator);
        }
        else
        {
            Iterator++;
        }
}

bool CPhysics::UpdateRender(btRigidBody* TObject)
{
    ISceneNode* Node = static_cast<ISceneNode *>(TObject->getUserPointer());

    if(Node == NULL)
    {
        return false;
    }
    const btVector3& Point = TObject->getCenterOfMassPosition();
    Node->setPosition(vector3df((f32)Point[0], (f32)Point[1], (f32)Point[2]));

    btVector3 EulerRotation;
    CPhysics::QuaternionToEuler(TObject->getOrientation(), EulerRotation);
    Node->setRotation(vector3df(EulerRotation[0], EulerRotation[1], EulerRotation[2]));
    return true;
}

btRigidBody* CPhysics::CreateBox(const btVector3 &TPosition, const vector3df &TScale, btScalar TMass)
{
    ISceneNode* Node = CPhysics::smgr->addCubeSceneNode(1.0f);
	Node->setScale(TScale);
	Node->setMaterialFlag(EMF_LIGHTING, true);
	Node->setMaterialFlag(EMF_NORMALIZE_NORMALS, true);
	//Node->setMaterialTexture(0, driver->getTexture("rust0.jpg"));

	btTransform Transform;
	Transform.setIdentity();
	Transform.setOrigin(TPosition);

	btDefaultMotionState *MotionState = new btDefaultMotionState(Transform);

	btVector3 HalfExtents(TScale.X * 0.5f, TScale.Y * 0.5f, TScale.Z * 0.5f);
	btCollisionShape *Shape = new btBoxShape(HalfExtents);

	btVector3 LocalInertia;
	Shape->calculateLocalInertia(TMass, LocalInertia);

	btRigidBody *RigidBody = new btRigidBody(TMass, MotionState, Shape, LocalInertia);

	RigidBody->setUserPointer((void *)(Node));
	RigidBody->setActivationState(DISABLE_DEACTIVATION);

	CPhysics::World->addRigidBody(RigidBody);
	CPhysics::Objects.push_back(RigidBody);
	return RigidBody;
}

btTriangleMesh* CPhysics::ConvertIrrMeshToBulletTriangleMesh(IMesh* pMesh,const vector3df& scaling)
{
  btVector3 vertices[3];
  u32 i,j,k,index,numVertices,numIndices;
  u16* mb_indices;
  btTriangleMesh *pTriMesh = new btTriangleMesh();
  for (i=0; i<pMesh->getMeshBufferCount(); i++)
  {
    IMeshBuffer* mb=pMesh->getMeshBuffer(i);
    if(mb->getVertexType()==EVT_STANDARD)
    {
      S3DVertex* mb_vertices=(S3DVertex*)mb->getVertices();
      mb_indices = mb->getIndices();
      numVertices = mb->getVertexCount();
      numIndices = mb->getIndexCount();
      for(j=0;j<numIndices;j+=3)
      {
        for (k=0;k<3;k++)
        {
          index = mb_indices[j+k];
          vertices[k] = btVector3(mb_vertices[index].Pos.X*scaling.X, mb_vertices[index].Pos.Y*scaling.Y, mb_vertices[index].Pos.Z*scaling.Z);
        }
        pTriMesh->addTriangle(vertices[0], vertices[1], vertices[2]);
      }
    }
    else if(mb->getVertexType()==EVT_2TCOORDS)
    {
      S3DVertex2TCoords* mb_vertices=(S3DVertex2TCoords*)mb->getVertices();
      mb_indices = mb->getIndices();
      numVertices = mb->getVertexCount();
      numIndices = mb->getIndexCount();
      for(j=0;j<numIndices;j+=3)
      {
        for (k=0;k<3;k++)
        {
          index = mb_indices[j+k];
          vertices[k] = btVector3(mb_vertices[index].Pos.X*scaling.X, mb_vertices[index].Pos.Y*scaling.Y, mb_vertices[index].Pos.Z*scaling.Z);
        }
        pTriMesh->addTriangle(vertices[0], vertices[1], vertices[2]);
      }
    }
  }
  return pTriMesh;
};

void CPhysics::QuaternionToEuler(const btQuaternion &TQuat, btVector3 &TEuler)
{
	btScalar W = TQuat.getW();
	btScalar X = TQuat.getX();
	btScalar Y = TQuat.getY();
	btScalar Z = TQuat.getZ();
	float WSquared = W * W;
	float XSquared = X * X;
	float YSquared = Y * Y;
	float ZSquared = Z * Z;
	TEuler.setX(atan2f(2.0f * (Y * Z + X * W), -XSquared - YSquared + ZSquared + WSquared));
	TEuler.setY(asinf(-2.0f * (X * Z - Y * W)));
	TEuler.setZ(atan2f(2.0f * (X * Y + Z * W), XSquared - YSquared - ZSquared + WSquared));
	TEuler *= RADTODEG;
};

btRigidBody* CPhysics::loadConvex(std::string filename, const btVector3 &TPosition, const vector3df &TScale, btScalar TMass)
{
    IAnimatedMeshSceneNode* Node = CPhysics::smgr->addAnimatedMeshSceneNode((IAnimatedMesh*)CPhysics::smgr->getMesh(filename.c_str()));
    btTriangleMesh* trimesh = CPhysics::ConvertIrrMeshToBulletTriangleMesh(Node->getMesh(), Node->getScale());

    btConvexShape* hull = new btConvexTriangleMeshShape(trimesh);
    hull->setUserPointer(hull);

    btVector3 localInertia(0,0,0);
    hull->calculateLocalInertia(TMass, localInertia);

	btQuaternion quat;
	quat.setEulerZYX(Node->getRotation().X,Node->getRotation().Y,Node->getRotation().Z);
	btTransform Transform2;
	Transform2.setIdentity();
	Transform2.setOrigin(TPosition);
	Transform2.setRotation(quat);

	btDefaultMotionState *MotionState2 = new btDefaultMotionState(Transform2);

	btRigidBody* RigidBody = new btRigidBody(TMass, MotionState2, hull, localInertia);

	RigidBody->setUserPointer((void *)(Node));
	RigidBody->setActivationState(DISABLE_DEACTIVATION);

	CPhysics::World->addRigidBody(RigidBody);
	CPhysics::Objects.push_back(RigidBody);

	return RigidBody;
}

list<btRigidBody *> CPhysics::getObjectList()
{
    return CPhysics::Objects;
}

btDiscreteDynamicsWorld* CPhysics::getWorld()
{
    return CPhysics::World;
}

So, to use this class, add

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CPhysics* Physics = new CPhysics(smgr, driver, Timer, btVector3(0, -500, 0), MapNode);

Somewhere before your main loop. Here, MapNode is a pointer to your Level geometry scene node (in this case, its an AnimatedMeshSceneNode, but you can change that to whatever type your Level is)

After that, simply call

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Physics->Update();

At the start of your Game Loop.

If you also want the debug drawer, then include DebugDraw.h -

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#ifndef _DEBUGDRAW_H
#define _DEBUGDRAW_H

enum DebugDrawModes
{
    DBG_NoDebug=0,
    DBG_DrawWireframe = 1,
    DBG_DrawAabb=2,
    DBG_DrawFeaturesText=4,
    DBG_DrawContactPoints=8,
    DBG_NoDeactivation=16,
    DBG_NoHelpText = 32,
    DBG_DrawText=64,
    DBG_ProfileTimings = 128,
    DBG_EnableSatComparison = 256,
    DBG_DisableBulletLCP = 512,
    DBG_EnableCCD = 1024,
    DBG_MAX_DEBUG_DRAW_MODE
};

//Courtesy of randomMESH
class DebugDraw : public btIDebugDraw
{

public:

   DebugDraw(IrrlichtDevice* const device) :
      mode(DBG_NoDebug), driver(device->getVideoDriver()), logger(device->getLogger())
   {

   }

   void drawLine(const btVector3& from, const btVector3& to, const btVector3& color)
   {
      SColor newColor(255, (u32)color[0], (u32)color[1], (u32)color[2]);
      if (color[0] <= 1.0 && color[0] > 0.0)
         newColor.setRed((u32)(color[0]*255.0));
      if (color[1] <= 1.0 && color[1] > 0.0)
         newColor.setGreen((u32)(color[1]*255.0));
      if (color[2] <= 1.0 && color[2] > 0.0)
         newColor.setBlue((u32)(color[2]*255.0));

      this->driver->draw3DLine(vector3df(from[0], from[1], from[2]), vector3df(to[0], to[1], to[2]), newColor);
   }

   void drawContactPoint(const btVector3& PointOnB, const btVector3& normalOnB, btScalar distance, int lifeTime, const btVector3& color)
   {
      static const SColor CONTACTPOINT_COLOR(255, 255, 255, 0); 
      const btVector3 to(PointOnB + normalOnB*distance);
      this->driver->draw3DLine(vector3df(PointOnB[0], PointOnB[1], PointOnB[2]),vector3df(to[0], to[1], to[2]),CONTACTPOINT_COLOR);
   }

   void reportErrorWarning(const char* text)
   {
      this->logger->log(text, irr::ELL_ERROR);
   }

   void draw3dText(const btVector3& location, const char* text) { }
   void setDebugMode(int mode) { this->mode = mode; }
   int getDebugMode() const { return this->mode; }

private:

   int mode;
   IVideoDriver* const driver;
   ILogger* logger;
};

#endif

Add the following after creating the physics world -

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	DebugDraw* Debug = new DebugDraw(device);
	Physics->getWorld()->setDebugDrawer(Debug);
	Debug->setDebugMode(DBG_DrawAabb | DBG_DrawWireframe);

Add this before your Game Loop -

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    SMaterial debugMat;
    debugMat.Lighting = false;

And, finally, add this before your call to driver->endScene() -

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        driver->setMaterial(debugMat);
        driver->setTransform(ETS_WORLD, IdentityMatrix);
        Physics->getWorld()->debugDrawWorld();

For a simple test, here is the code to create the stack of boxes as shown in the screenie -

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	int xshift = 0;
	int yshift = 0;
	for(yshift=0;yshift<=7;yshift++)
		for(xshift=0;xshift<=7;xshift++)
		{
			btRigidBody* DummyRigidBody = Physics->CreateBox(btVector3((100+(50*xshift)),10+(50*yshift),1500),vector3df(50,50,50),40);
		};

Any comments/critiques are welcome

Enjoy!

Posted: Wed Jul 14, 2010 4:38 pm

by serengeor

I am really thankful to you .
Will try to integrate into my game

Definately worth atention

Edit: And here comes the ugly errors

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error C2719: 'Gravity': formal parameter with __declspec(align('16')) won't be aligned
 error C2719: 'Gravity': formal parameter with __declspec(align('16')) won't be aligned
: error C2039: 'getNode' : is not a member of 'irr::scene::IAnimatedMeshSceneNode'

Anyone knows what could the first two mean?

Posted: Wed Jul 14, 2010 5:57 pm

by shadowslair

For the first two I`d try googling it without the keywords specific for your app. This is what I usually do for errors I don`t know.

For the second you may try removing the "getNode" call. Maybe (Map->getNode()) may become (Map) or sth alike.

Posted: Thu Jul 15, 2010 4:24 am

by Buck1000

Ah, yes, sorry about that, I forgot some code specific to my project in there

In the constructor -

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CPhysics::CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, btVector3 Gravity, IAnimatedMeshSceneNode* Map)

There is code to automatically generate the map physics mesh, from an Animated Scene Node. If you look closely, down where the btRigidBody's user pointer is assigned, is where that call is being made (getNode). Just remove the ->getNode() part.

So, where you see this -

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RigidBody->setUserPointer((void *)(Map->getNode()));

Change it too this -

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RigidBody->setUserPointer((void *)(Map));

And it should work

I'm glad that someone found a use for it! If you have any more trouble, I'll be glad to help.

As for the first problem, concerning "Gravity", I have no idea. A bit of googling shows that the error might be specific to an MS compiler. You can keep on trying to find a solution, but if you can't, you can always replace it with a float, instead of a btVector.

In CPhysics.h, change

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 btVector3 Gravity;

to

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float Gravity;

and

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CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, btVector3 Gravity, IAnimatedMeshSceneNode* Map);

to

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CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, float Gravity, IAnimatedMeshSceneNode* Map);

and, in CPhysics.cpp, change the constructor too

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CPhysics::CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, float Gravity, IAnimatedMeshSceneNode* Map) 
{ 
   btDefaultCollisionConfiguration* CollisionConfiguration = new btDefaultCollisionConfiguration(); 
   btBroadphaseInterface* BroadPhase = new btAxisSweep3(btVector3(-100000, -100000, -100000), btVector3(100000, 100000, 100000)); 
   BroadPhase->getOverlappingPairCache()->setInternalGhostPairCallback(new btGhostPairCallback()); 
   btCollisionDispatcher* Dispatcher = new btCollisionDispatcher(CollisionConfiguration); 
   btSequentialImpulseConstraintSolver* Solver = new btSequentialImpulseConstraintSolver(); 
   CPhysics::World = new btDiscreteDynamicsWorld(Dispatcher, BroadPhase, Solver, CollisionConfiguration); 
   CPhysics::World->setGravity(btVector3(0,Gravity,0); 
   CPhysics::Gravity = Gravity; 
   CPhysics::smgr = smgr; 
   CPhysics::driver = driver; 
   CPhysics::Timer = Timer; 
   CPhysics::TimeStamp = Timer->getTime(); 
   CPhysics::DeltaTime = 0; 

   btTriangleMesh* indexVertexArrays = CPhysics::ConvertIrrMeshToBulletTriangleMesh(Map->getMesh(),Map->getMesh()->getScale()); 
   btBvhTriangleMeshShape* trimeshShape = new btBvhTriangleMeshShape(indexVertexArrays, true); 

   btQuaternion quat; 
   quat.setEulerZYX(0,0,0); 
   btTransform Transform2; 
   Transform2.setIdentity(); 
   Transform2.setOrigin(btVector3(0,0,0)); 
   Transform2.setRotation(quat); 

   btDefaultMotionState *MotionState2 = new btDefaultMotionState(Transform2); 

   btRigidBody *RigidBody = new btRigidBody(0, MotionState2, trimeshShape); 

   RigidBody->setUserPointer((void *)(Map->getNode())); 

   CPhysics::World->addRigidBody(RigidBody); 
   CPhysics::Objects.push_back(RigidBody); 

   RigidBody->setCollisionFlags(btCollisionObject::CF_STATIC_OBJECT); 
}

Gravity in this case should be a negative value. I personally use -500

I haven't tested that out, but it should work.

Posted: Thu Jul 15, 2010 8:55 am

by serengeor

I think that this code

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CPhysics::CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, btVector3 Gravity, IAnimatedMeshSceneNode* Map)

Should be like this

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CPhysics::CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, btVector3 & Gravity, IAnimatedMeshSceneNode* Map)

Everything is okay now
Just need to make function that would destroy everything :]

Edit:
Any advice on how to remove whole physics stuff and irrlicht nodes that are used by physics?
Edit2: After I Destroy every single thing including the physics class it still leaks about 1,000K

Posted: Sun Jul 18, 2010 6:18 pm

by Buck1000

Sorry for not replying quickly, I haven't bee online for long periods of time in awhile. Anyways, heres the code I use:

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void CPhysics::remove()
{
    for(list<btRigidBody *>::Iterator Iterator = CPhysics::Objects.begin(); Iterator != CPhysics::Objects.end();)
    {
        CPhysics::World->removeRigidBody((*Iterator));
        if((*Iterator)->getUserPointer()!=NULL)
            static_cast<ISceneNode *>((*Iterator)->getUserPointer())->remove();
        Iterator = CPhysics::Objects.erase(Iterator);
    }
    CPhysics::World->~btDiscreteDynamicsWorld();

    if(DEBUG_CONSOLE)
        cout<<"Cleaned Physics World"<<endl;
}

It works fine, but it may still have memory leaks, as I don't know how to check for those. Tell me what you think.

Posted: Mon Jul 19, 2010 11:35 am

by serengeor

Thanks for your reply, tough I already found what I needed

And still I may need help in future

Posted: Sun Jul 25, 2010 9:30 am

by serengeor

the memory leak sits in the physics constructor

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 btTriangleMesh* indexVertexArrays = CPhysics::ConvertIrrMeshToBulletTriangleMesh(Map->getMesh(),Map->getMesh()->getScale());

indexVertexArrays is new'ed so it needs to be deleted but since pointer is declared in the constructor it gets lost

Posted: Mon Jul 26, 2010 2:09 pm

by Garfinkle

I've done a convert of this code (as i think it is really helpful

) for the iPhone as the irrBullet system doesn't work and there doesn't seem to be any information on getting physics working on the iPhone.

Note: You may need to make a slight change to the Bullet includes depending on how you have included them into your project

e.g. changing

#include "Bullet-C-Api.h"
to
#include "Bullet/Bullet-C-Api.h"

etc.

Here is the code.

CPhysics.h

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#ifndef __CPHYSICS_H__
#define __CPHYSICS_H__

#include <string.h>
#include "irrlicht.h"
#include "Bullet-C-Api.h"
#include "btBulletCollisionCommon.h"
#include "btBulletDynamicsCommon.h"
#include "BulletCollision/CollisionDispatch/btGhostObject.h"

using namespace irr;
using namespace core;
using namespace scene;
using namespace video;

class CPhysics
{
public:
    CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, float Gravity, IAnimatedMeshSceneNode* Map);
    void Update();
    bool UpdateRender(btRigidBody* TObject);
    btTriangleMesh* ConvertIrrMeshToBulletTriangleMesh(IAnimatedMesh* pMesh,const vector3df &scaling);
    void QuaternionToEuler(const btQuaternion &TQuat, btVector3 &TEuler);
    void getConvexHull(IMesh *collMesh, btConvexHullShape *hullShape, IAnimatedMeshSceneNode* node);
    list<btRigidBody *> getObjectList();
	void Remove();
	
    btRigidBody* CreateBox(const btVector3 &TPosition, const vector3df &TScale, btScalar TMass);
    btRigidBody* loadConvex(const char* filename, const btVector3 &TPosition, const vector3df &TScale, btScalar TMass);
	
    btDiscreteDynamicsWorld* getWorld();

    ISceneManager* smgr;
    IVideoDriver* driver;
    ITimer* Timer;
    btDiscreteDynamicsWorld* World;
    list<btRigidBody *> Objects;
    float Gravity;
    float TimeStamp;
    float DeltaTime;
};

#endif

And the implementation file

CPhysics.mm

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#include "CPhysics.h"

#include "Bullet-C-Api.h"
#include "btBulletCollisionCommon.h"
#include "btBulletDynamicsCommon.h"
#include "BulletCollision/CollisionDispatch/btGhostObject.h"

CPhysics::CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, float Gravity, IAnimatedMeshSceneNode* Map)
{
	btDefaultCollisionConfiguration* CollisionConfiguration = new btDefaultCollisionConfiguration();
	btBroadphaseInterface* BroadPhase = new btAxisSweep3(btVector3(-100000, -100000, -100000), btVector3(100000, 100000, 100000));
	BroadPhase->getOverlappingPairCache()->setInternalGhostPairCallback(new btGhostPairCallback());
	btCollisionDispatcher* Dispatcher = new btCollisionDispatcher(CollisionConfiguration);
	btSequentialImpulseConstraintSolver* Solver = new btSequentialImpulseConstraintSolver();
	CPhysics::World = new btDiscreteDynamicsWorld(Dispatcher, BroadPhase, Solver, CollisionConfiguration);
	CPhysics::World->setGravity(btVector3(0,Gravity,0));
	CPhysics::Gravity = Gravity;
	CPhysics::smgr = smgr;
	CPhysics::driver = driver;
	CPhysics::Timer = Timer;
	CPhysics::TimeStamp = Timer->getTime();
	CPhysics::DeltaTime = 0;
	printf("Mesh: %s", Map->getName());
	printf("Scale: X:%f Y:%f Z:%f", Map->getScale().X, Map->getScale().Y, Map->getScale().Z);
	btTriangleMesh* indexVertexArrays = CPhysics::ConvertIrrMeshToBulletTriangleMesh(Map->getMesh(),Map->getScale());
	btBvhTriangleMeshShape* trimeshShape = new btBvhTriangleMeshShape(indexVertexArrays, true);
	
	btQuaternion quat;
	quat.setEulerZYX(0,0,0);
	btTransform Transform2;
	Transform2.setIdentity();
	Transform2.setOrigin(btVector3(0,0,0));
	Transform2.setRotation(quat);
	
	btDefaultMotionState *MotionState2 = new btDefaultMotionState(Transform2);
	
	btRigidBody *RigidBody = new btRigidBody(0, MotionState2, trimeshShape);
	
	RigidBody->setUserPointer((void *)(Map));
	
	CPhysics::World->addRigidBody(RigidBody);
	CPhysics::Objects.push_back(RigidBody);
	
	RigidBody->setCollisionFlags(btCollisionObject::CF_STATIC_OBJECT);
	delete(indexVertexArrays);
}

void CPhysics::Update()
{
    CPhysics::DeltaTime = CPhysics::Timer->getTime() - CPhysics::TimeStamp;
    CPhysics::TimeStamp = CPhysics::Timer->getTime();
    CPhysics::World->stepSimulation(CPhysics::DeltaTime * 0.001f, 2);
    for(list<btRigidBody *>::Iterator Iterator = CPhysics::Objects.begin(); Iterator != CPhysics::Objects.end();)
        if(!CPhysics::UpdateRender(*Iterator))
        {
            Iterator = CPhysics::Objects.erase(Iterator);
        }
        else
        {
            Iterator++;
        }
}

bool CPhysics::UpdateRender(btRigidBody* TObject)
{
    ISceneNode* Node = static_cast<ISceneNode *>(TObject->getUserPointer());
	
    if(Node == NULL)
    {
        return false;
    }
    const btVector3& Point = TObject->getCenterOfMassPosition();
    Node->setPosition(vector3df((f32)Point[0], (f32)Point[1], (f32)Point[2]));
	
    btVector3 EulerRotation;
    CPhysics::QuaternionToEuler(TObject->getOrientation(), EulerRotation);
    Node->setRotation(vector3df(EulerRotation[0], EulerRotation[1], EulerRotation[2]));
    return true;
}

btRigidBody* CPhysics::CreateBox(const btVector3 &TPosition, const vector3df &TScale, btScalar TMass)
{
    ISceneNode* Node = CPhysics::smgr->addCubeSceneNode(1.0f);
	Node->setScale(TScale);
	Node->setMaterialFlag(EMF_LIGHTING, true);
	Node->setMaterialFlag(EMF_NORMALIZE_NORMALS, true);
	//Node->setMaterialTexture(0, driver->getTexture("rust0.jpg"));
	
	btTransform Transform;
	Transform.setIdentity();
	Transform.setOrigin(TPosition);
	
	btDefaultMotionState *MotionState = new btDefaultMotionState(Transform);
	
	btVector3 HalfExtents(TScale.X * 0.5f, TScale.Y * 0.5f, TScale.Z * 0.5f);
	btCollisionShape *Shape = new btBoxShape(HalfExtents);
	
	btVector3 LocalInertia;
	Shape->calculateLocalInertia(TMass, LocalInertia);
	
	btRigidBody *RigidBody = new btRigidBody(TMass, MotionState, Shape, LocalInertia);
	
	RigidBody->setUserPointer((void *)(Node));
	RigidBody->setActivationState(DISABLE_DEACTIVATION);
	
	CPhysics::World->addRigidBody(RigidBody);
	CPhysics::Objects.push_back(RigidBody);
	return RigidBody;
}

btTriangleMesh* CPhysics::ConvertIrrMeshToBulletTriangleMesh(IAnimatedMesh* pMesh,const vector3df &scaling)
{
	btVector3 vertices[3];
	u32 i,j,k,index,numVertices,numIndices;
	u16* mb_indices;
	btTriangleMesh *pTriMesh = new btTriangleMesh();
	for (i=0; i<pMesh->getMeshBufferCount(); i++)
	{
		IMeshBuffer* mb=pMesh->getMeshBuffer(i);
		if(mb->getVertexType()==EVT_STANDARD)
		{
			S3DVertex* mb_vertices=(S3DVertex*)mb->getVertices();
			mb_indices = mb->getIndices();
			numVertices = mb->getVertexCount();
			numIndices = mb->getIndexCount();
			for(j=0;j<numIndices;j+=3)
			{
				for (k=0;k<3;k++)
				{
					index = mb_indices[j+k];
					vertices[k] = btVector3(mb_vertices[index].Pos.X * scaling.X, 
											mb_vertices[index].Pos.Y * scaling.Y, 
											mb_vertices[index].Pos.Z * scaling.Z);
				}
				pTriMesh->addTriangle(vertices[0], vertices[1], vertices[2]);
			}
		}
		else if(mb->getVertexType()==EVT_2TCOORDS)
		{
			S3DVertex2TCoords* mb_vertices=(S3DVertex2TCoords*)mb->getVertices();
			mb_indices = mb->getIndices();
			numVertices = mb->getVertexCount();
			numIndices = mb->getIndexCount();
			for(j=0;j<numIndices;j+=3)
			{
				for (k=0;k<3;k++)
				{
					index = mb_indices[j+k];
					vertices[k] = btVector3(mb_vertices[index].Pos.X * scaling.X, 
											mb_vertices[index].Pos.Y * scaling.Y, 
											mb_vertices[index].Pos.Z * scaling.Z);
				}
				pTriMesh->addTriangle(vertices[0], vertices[1], vertices[2]);
			}
		}
	}
	return pTriMesh;
};

void CPhysics::QuaternionToEuler(const btQuaternion &TQuat, btVector3 &TEuler)
{
	btScalar W = TQuat.getW();
	btScalar X = TQuat.getX();
	btScalar Y = TQuat.getY();
	btScalar Z = TQuat.getZ();
	float WSquared = W * W;
	float XSquared = X * X;
	float YSquared = Y * Y;
	float ZSquared = Z * Z;
	TEuler.setX(atan2f(2.0f * (Y * Z + X * W), -XSquared - YSquared + ZSquared + WSquared));
	TEuler.setY(asinf(-2.0f * (X * Z - Y * W)));
	TEuler.setZ(atan2f(2.0f * (X * Y + Z * W), XSquared - YSquared - ZSquared + WSquared));
	TEuler *= RADTODEG;
};

btRigidBody* CPhysics::loadConvex(const char* filename, const btVector3 &TPosition, const vector3df &TScale, btScalar TMass)
{
    IAnimatedMeshSceneNode* Node = CPhysics::smgr->addAnimatedMeshSceneNode((IAnimatedMesh*)CPhysics::smgr->getMesh(filename));
    btTriangleMesh* trimesh = CPhysics::ConvertIrrMeshToBulletTriangleMesh(Node->getMesh(), Node->getScale());
	
    btConvexShape* hull = new btConvexTriangleMeshShape(trimesh);
    hull->setUserPointer(hull);
	
    btVector3 localInertia(0,0,0);
    hull->calculateLocalInertia(TMass, localInertia);
	
	btQuaternion quat;
	quat.setEulerZYX(Node->getRotation().X,Node->getRotation().Y,Node->getRotation().Z);
	btTransform Transform2;
	Transform2.setIdentity();
	Transform2.setOrigin(TPosition);
	Transform2.setRotation(quat);
	
	btDefaultMotionState *MotionState2 = new btDefaultMotionState(Transform2);
	
	btRigidBody* RigidBody = new btRigidBody(TMass, MotionState2, hull, localInertia);
	
	RigidBody->setUserPointer((void *)(Node));
	RigidBody->setActivationState(DISABLE_DEACTIVATION);
	
	CPhysics::World->addRigidBody(RigidBody);
	CPhysics::Objects.push_back(RigidBody);
	
	return RigidBody;
}

list<btRigidBody *> CPhysics::getObjectList()
{
    return CPhysics::Objects;
}

btDiscreteDynamicsWorld* CPhysics::getWorld()
{
    return CPhysics::World;
} 

void CPhysics::Remove()
{
    for(list<btRigidBody *>::Iterator Iterator = CPhysics::Objects.begin(); Iterator != CPhysics::Objects.end();)
    {
        CPhysics::World->removeRigidBody((*Iterator));
        if((*Iterator)->getUserPointer()!=NULL)
            static_cast<ISceneNode *>((*Iterator)->getUserPointer())->remove();
        Iterator = CPhysics::Objects.erase(Iterator);
    }
    CPhysics::World->~btDiscreteDynamicsWorld();

}

I haven't converted the DebugDraw.h file yet as there seem to be quite a few changes required and it wasn't essential to get it up and running.

I do seem to be having one problem though

when creating the physics world I'm using the following code

Code: Select all

Physics = new CPhysics(smgr, driver, timer, -500.0f, ((IAnimatedMeshSceneNode*)node));

where node is an object loaded in a irrScene file.

When the creation gets to the following line in CPhysics.mm

Code: Select all

	btTriangleMesh* indexVertexArrays = CPhysics::ConvertIrrMeshToBulletTriangleMesh(Map->getMesh(),Map->getScale());

the app just crashes with a EXC_BAD_ACCESS error, which if you've not done iPhone programming, means that the code is trying to access an object that has
a) not yet been created (does not exist in memory)
b) has been deleted/released or dropped and the memory pointer no longer exists

The issue seems to be with the Map->getMesh() part of the call.

Has anyone had issues loading scene file objects into the physics engine or referencing the Meshes?

Thanks in advance and hope the changes above help any fellow iPhone developers get started with physics.

And thanks to Buck1000 for providing this framework that got me started

[/b]

Posted: Mon Jul 26, 2010 2:51 pm

by Garfinkle

Worked out where I was going wrong.

I was trying to cast an cast a ISceneNode straight to a IAnimatedMeshSceneNode when the node was in fact a IMeshSceneNode so the cast was failing.

I have improved the code to handle loading objects from scene files.

in CPhysics.h add the following constructor above the existing one.

Code: Select all

CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, float Gravity, ISceneNode* Map);

and in the CPhysics.m add the following constructor above the existing one.

Code: Select all

CPhysics::CPhysics(ISceneManager* smgr, IVideoDriver* driver, ITimer* Timer, float Gravity, ISceneNode* Map)
{
	IAnimatedMeshSceneNode* animatedMesh = 0;
	switch(Map->getType())
	{
		case scene::ESNT_MESH:
			animatedMesh = static_cast<IAnimatedMeshSceneNode*>(Map);
			printf("\nSetting Mesh to IAnimatedMeshSceneNode\n");
			break;
		
	}
	CPhysics::CPhysics(smgr, driver, Timer, Gravity, animatedMesh);
}

What this now does is allows a second constructor to intercept if you are loading an object as a ISceneNode. If you are then it will convert it to type IAnimatedMeshSceneNode if it is an IMeshSceneNode using dynamic casting and then pass it to the original constructor.

If you call the same constructor with a IAnimatedMeshSceneNode and not a ISceneNode then it will use the default constructor and run as normal.

This could be expanded in the future to handle conversion of other Node Types to create a more dynamic loading system.

EDIT: Corrected errors in my conversion from IMeshSceneNode to IAnimateMeshSceneNode

Posted: Mon Jul 26, 2010 8:11 pm

by serengeor

Remember not to loose the indexVertexArrays pointer in the constructor or nasty memory leaks will occur due to conversion function which returns new'ed trimesh object!

Posted: Tue Jul 27, 2010 8:14 am

by Garfinkle

@serengeor: Does the indexVertexArray need to be kept or can it just simply be deleted at the end of the function using delete(indexVertexArray)? Does it need to be maintained for the new trimeshShape or is it never used again after the trimeshShape is created?

I seem to be having a slight issue with the following lines in the constructor

Code: Select all

   CPhysics::Gravity = Gravity;
   CPhysics::smgr = smgr;
   CPhysics::driver = driver;
   CPhysics::Timer = Timer;
   CPhysics::TimeStamp = Timer->getTime();
   CPhysics::DeltaTime = 0;

The variables are set here perfectly but in the other methods they always appear to be set to 0x0. It seems that once the method ends these variables are being cleared and not retained throughout the whole instance of the class.

The class instance is only ever being created once and I have not yet implement any calls to the Remove function.

Is there any reason why the variables would not be retained and keep setting themselves back to 0x0 (NULL)?

Thanks in advance.

[/b]

Posted: Tue Jul 27, 2010 10:07 am

by Garfinkle

I decided to aim at fixing the 170 errors being thrown by using DebugDraw.h on the iPhone.

Well....turned out easier than expected.

Add the following to the top of DebugDraw.h and its all working fine.

Code: Select all

#include "irrlicht.h"
using namespace irr;
using namespace core;
using namespace scene;
using namespace video;

Posted: Wed Jul 28, 2010 6:14 pm

by serengeor

Garfinkle wrote:I decided to aim at fixing the 170 errors being thrown by using DebugDraw.h on the iPhone.

Well....turned out easier than expected.

Add the following to the top of DebugDraw.h and its all working fine.
Code: Select all
#include "irrlicht.h"
using namespace irr;
using namespace core;
using namespace scene;
using namespace video;

Who could have guessed that !

Good job anyways

Posted: Sun Aug 01, 2010 8:43 pm

by serengeor

@serengeor: Does the indexVertexArray need to be kept or can it just simply be deleted at the end of the function using delete(indexVertexArray)? Does it need to be maintained for the new trimeshShape or is it never used again after the trimeshShape is created?

It does have to be kept as long as you use trimesh shape when you delete it you should delete indexvertexarray too.
deleting it in the same function would result in a crash.