I’ve made the following test to figure out how to use physics and collisions. I’m happy with the physics part, I think, and thought the collisions looked simple enough, yet my moving target doesn’t seem to hit the collision plane I placed in the scene graph. Any suggestions on what I’m missing?

#include "pandaFramework.h"
#include "pandaSystem.h"
#include "mouseButton.h"
#include "texturePool.h"

#include "actorNode.h"
#include "forceNode.h"
#include "physicsManager.h"
#include "linearEulerIntegrator.h"
#include "physical.h"
#include "forces.h"

#include "collisionTraverser.h"
#include "collisionHandlerFluidPusher.h"
#include "collisionSphere.h"
#include "collisionPlane.h"

#include "lvector3.h"
#include "plane.h"

PandaFramework framework;
WindowFramework *window;
class testObj : public Physical
	int doobie;

int main(int argc, char *argv[]) 
	//open a new window framework
	framework.open_framework(argc, argv);
    //set the window title to My Panda3D Window
	framework.set_window_title("My Panda3D Window");
	//open the window
	window = framework.open_window();
	// This part sets up an object for physics, as in the physics tests.
	// create a physics manager
	PhysicsManager pm;
	// to do anything, the physics manager needs an integrator. Here, one for linear forces.
	pm.attach_linear_integrator( new LinearEulerIntegrator );
	// create an actor node and add it to the scene graph under the render node.
	// the actor node already has a physical living inside it when we create it.
	NodePath annp = window->get_render().attach_new_node( new ActorNode("actor_node") );
	NodePath annp2 = window->get_render().attach_new_node( new ActorNode("actor_node2") );

	// register the node with the physics manager
	pm.attach_physical_node( (PhysicalNode*)annp.node() );
	pm.attach_physical_node( (PhysicalNode*)annp2.node() );
	// create a force		
	NodePath fnnp(new ForceNode("force_node"));
	((ForceNode*)fnnp.node() )->add_force( new LinearVectorForce( 0, 1.0, 0, 0.1) );
	fnnp.reparent_to( annp );
	fnnp.output(cout); cout << endl;
	annp.output(cout); cout << endl;
	PT(ActorNode) an((ActorNode*)annp.node());
	an->get_physical(0)->add_linear_force( (LinearForce*)((ForceNode*)fnnp.node())->get_force(0) );

	// this part prepares the collision system
	// create a collision solid attached to our actor, in this case a sphere
	// around the actor.
	NodePath fromObj = annp.attach_new_node( new CollisionNode("an-col-node") );
	CollisionNode *n;
	n = (CollisionNode*) fromObj.node();
	n->add_solid( new CollisionSphere(0,0,0,1) );
	// create a collision solid that will form something to collide with.
	NodePath toObj = window->get_render().attach_new_node( new CollisionNode("p-col-node") );
	n = (CollisionNode*) toObj.node();
	n->add_solid(  new CollisionPlane( Planef( LVector3f(0, -1, 0 ), LVector3f(0,0,0) ) ) );
	// now we need a collision handler for the object
	CollisionHandlerFluidPusher *cha = new CollisionHandlerFluidPusher();
	cha->add_collider(fromObj, annp );

	// then we need a collision traverser
	CollisionTraverser traverser;
	traverser.add_collider( fromObj, cha );	
	// and finally, we load some stuff to look at!
	NodePath m = window->load_model(framework.get_models(), "planet_sphere.egg.pz");
 	PT(Texture) mt = TexturePool::load_texture("earth_1k_tex.jpg");
 	m.reparent_to( annp );

 	for( int cc = 0; cc < 100; ++cc)
		// do physics
		// do collisions
		traverser.traverse( window->get_render() );
		// do events
 		cout << annp.get_pos() << endl;
	//close the window framework
	return (0);

Looks right, at a glance. You should probably use a PhysicsCollisionHandler rather than a CollisionHandlerPusher or CollisionHandlerFluidPusher. The PhysicsCollisionHandler is better suited for pushing back on an object operated by the physics system; it’s possible that with the other kinds of pushers you don’t see the push-back happening because the physics system might override the collision.


yup, that’s got it, cheers.