Problem with NewtonBodyAddForce

[Mancuso Raffaele]

hi all. I'm building an OOP framework to integrate newton with irrlicht. When i add a force before the loop, it's all ok. But when i add a force in the loop or in a IEventReceiver derived class, the force is not added. i suspect that Newton call NewtonApllyForceAndTorqueEvent function one time. Why? here are a part of my code:

Code: Select all

class SceneNode {
public:
//[...] costructor,destructor and others function 
void AddForce(irr::core::vector3df force);
//attributes
raf::Newt::World* world;
NewtonCollision* collision;
NewtonBody* body;
irr::scene::ISceneNode* node;
std::vector<irr::core::vector3df> forces;
static void __cdecl PhisicsSetForceAndTorqueEvent (const NewtonBody* body);
static void __cdecl PhisicsSetTransformEvent(const NewtonBody* body, const float* matrix);
};//class ARES_API SceneNode {
//----------------------------------------Phisics.cpp file--------------------
void __cdecl raf::Newt::SceneNode::PhisicsSetTransformEvent(const NewtonBody* body, const float* matrix) {
	NewtonBodySetMatrix(body,matrix);
	core::matrix4 irr_mat;
	memcpy(irr_mat.M, matrix, sizeof(float)*16);
	irr_mat.setTranslation(irr_mat.getTranslation()*NewtonToIrr);
	raf::Newt::SceneNode* p_node=(raf::Newt::SceneNode*)NewtonBodyGetUserData(body);
	scene::ISceneNode* node=p_node->node;
	node->setPosition(irr_mat.getTranslation());
	node->setRotation(irr_mat.getRotationDegrees());	
}

void __cdecl raf::Newt::SceneNode::PhisicsSetForceAndTorqueEvent (const NewtonBody* body) 
{
raf::Newt::SceneNode* p_node=(raf::Newt::SceneNode*)NewtonBodyGetUserData(body);
for(int i=0;i<p_node->forces.size();i++) {
     raf::Newt::dVector f;
     f.m_x=p_node->forces[i].X;
     f.m_y=p_node->forces[i].Y;
     f.m_z=p_node->forces[i].Z;
     NewtonBodyAddForce(body,&f.m_x);
}
return;	
}
void raf::Newt::SceneNode::AddForce(irr::core::vector3df force) {
	this->forces.push_back(force);
}
//----------------------------a part of main.cpp---------------------------
class MyeventReceiver_class:public IEventReceiver{
public:
bool OnEvent(SEvent event) {
  //camera->OnEvent(event);
  if(event.EventType==EET_KEY_INPUT_EVENT&&
  event.KeyInput.Key==KEY_KEY_S&&
  event.KeyInput.PressedDown==false) {
       p_node->AddForce(core::vector3df(0,-100,-100));
}
return false;
}
};
[...]
device->setEventReceiver(&MyEventClass);
while(device->run()) {
 nWorld->Update(device);//NewtonUpdate(this->world, this->timer.GetElapsedSeconds());
driver->beginScene(true,true,video::SColor(255,0,0,0));
smgr->drawAll();
driver->endScene();	
} 

When i press s key, not happens!! Why?
I can public all of my code.
Thanks, Raffaele ( Ares FPS)

[magicat]

Its been a while since I've used Newton, but it could be like you said, it might only allow you to call AddForce once per AddForceAndTorqueEvent. I think you would be better off adding up all your forces(just add the vectors) into a total force vector in your loop, then calling NewtonBodySetForce() with the total force. Also, it looks like to me in your code you're only applying the x direction force ? Anyways, adding up the forces then using SetForce() would be the cleanest way to do it from what I remember of Newton. Something to remember with your system you've got going is that you're gonna need a way to remove forces from your force vector, so you might wanna take that into consideration.

[sudi]

The add force function only takes effect from the callback function.....read the manual

[Mancuso Raffaele]

I think you would be better off adding up all your forces(just add the vectors) into a total force vector in your loop, then calling NewtonBodySetForce() with the total force

very good idea. Thanks

Also, it looks like to me in your code you're only applying the x direction force ?

Why? Take a look in the code

Code: Select all

raf::Newt::dVector f;
f.m_x=p_node->forces[i].X;
f.m_y=p_node->forces[i].Y;
f.m_z=p_node->forces[i].Z;
NewtonBodySetForce(body,&f.m_x);

The add force function only takes effect from the callback function.....read the manual

yes, I read the newton tutorial. in fact i add force with the callback function raf::Newt::SceneNode::PhisicsSetForceAndTorqueEvent. This function read from a vector (std::vector<irr::core::vector3df> forces) all forces applied to a body and applied them sequentially. The problem is that i don't want that a force is applied to a body immediately when the body is created, but when i click a key. in this case the callback function PhisicsSetForceAndTorqueEvent is not called (because it is called one time, when the body is created), so the force is not applied. Maybe i need remove and recreate the body in the same position\rotation and applie the force, but it is not a great metod. Is there a metod to force Newton to call PhisicsSetForceAndTorqueEvent every time NewtonUpdate is called?
thanks,
Raffaele ( Ares FPS )

[Acki]

Well, this is not an Irrlicht related question !!!
A Newton forum would help better...

Anyways, try to use the ApplyForceEventHandler(...) callback