Box2d contact listener doesnt work right at presolve

Question

i am creating a game using box2d. I have balls and when a ball passes through a sensor i need to increase score... Now when i resolve the contact in beginContact everything is ok

public ContactListener createContactListener() {
        return new ContactListener() {
            @Override
            public void beginContact(Contact contact) {

                if(contact.getFixtureA().getUserData() == "ball" && contact.getFixtureB().getUserData() == "cup_sensor"){
                    //contact.getFixtureA().setUserData("ball_inactive");
                    Constants.LC.score++;

                    //contact.getFixtureA().getFilterData().maskBits = 0xffff & 0x0002;
                    //contact.setEnabled(false);
                }

                if(contact.getFixtureB().getUserData() == "ball" && contact.getFixtureA().getUserData() == "cup_sensor"){
                    //contact.getFixtureB().setUserData("ball_inactive");
                    Constants.LC.score++;
                    //contact.getFixtureB().getFilterData().maskBits = 0xffff & 0x0002;
                    //contact.setEnabled(false);
                }
            }

            @Override
            public void endContact(Contact contact) {

            }

            @Override
            public void preSolve(Contact contact, Manifold oldManifold) {

            }

            @Override
            public void postSolve(Contact contact, ContactImpulse impulse) {
            }
        };
    }

every thing works like a charm

But for some reason i want to do it in presolve

return new ContactListener() {
    @Override
    public void beginContact(Contact contact) {


    }

    @Override
    public void endContact(Contact contact) {

    }

    @Override
    public void preSolve(Contact contact, Manifold oldManifold) {
        if(contact.getFixtureA().getUserData() == "ball" && contact.getFixtureB().getUserData() == "cup_sensor"){
            //contact.getFixtureA().setUserData("ball_inactive");
            Constants.LC.score++;

            //contact.getFixtureA().getFilterData().maskBits = 0xffff & 0x0002;
            //contact.setEnabled(false);
        }

        if(contact.getFixtureB().getUserData() == "ball" && contact.getFixtureA().getUserData() == "cup_sensor"){
            //contact.getFixtureB().setUserData("ball_inactive");
            Constants.LC.score++;
            //contact.getFixtureB().getFilterData().maskBits = 0xffff & 0x0002;
            //contact.setEnabled(false);
        }
    }

    @Override
    public void postSolve(Contact contact, ContactImpulse impulse) {
    }
};

}

now it does not work... it does not passes the if condition... so score does not increase...

Please support me with that problem

Edit: i did some debugging. seems like on presolve contact.getFixtureA().getUserData() for sensor is returning null. I have no idea why

iforce2d iforce2d · Accepted Answer · 2014-06-13T20:01:52

The PreSolve callback lets you do something right before the collision response impulses are calculated. Sensors have no collision response, so PreSolve will not be called for them.

Box2d contact listener doesnt work right at presolve

1 Answers