CollisionResults, Ray, and a player character question

Troubleshooting General Help
1

I have a player character, and my character is just the “Models/Oto/Oto.mesh.xml” model loaded from the assetManager. I’ve gone through the beginner tutorial which shows how to do the picking, but in the tutorial, it uses new Ray(cam.getLocation(), cam.getDirection()) or something to that affect. How would I do this same thing, but from the model? I tried setting my location to be the localTranslation of the model, but that sets the mark to be the middle of the Oto. I tried taking that Vector3f, and calling add(), but my results are all over the place. I would figure there would be an easier method to shooting a ray from the front of the model and detecting the closest collision from that.

Thanks for the help!
~Jeremy

2

I guess it would help to note that I’m using the chase cam. The idea would be that the cam follows behind the character, and the bullets would shoot from the character. So basically I’m just looking to see how I can do picking from the point of the character and not the cam.

I was looking at some other tutorials and stuff, in this situation, would I create another camera from the character’s point of view, but use the chase cam as my primary cam?

3

I have done something like that in a RobotWar example that is floating arround here somehwere and in example repository.
Here is the actionlistener if this helps you get some ideas:

[java]
public void onAction(String name, boolean isPressed, float tpf) {
if (gameFinished) {
return;
}
if (name.equals(“Shoot”) && isPressed) {

        if (playerLaserBeam == null) {
            Vector2f click2d = inputManager.getCursorPosition();
            Vector3f click3d = cam.getWorldCoordinates(new Vector2f(click2d.x, click2d.y), 0f).clone();
            Vector3f dir = cam.getWorldCoordinates(new Vector2f(click2d.x, click2d.y), 1f).subtractLocal(click3d).normalizeLocal();
            Ray ray = new Ray(click3d, dir);
            Plane ground = new Plane(Vector3f.UNIT_Y, 0);
            Vector3f groundpoint = new Vector3f();
            ray.intersectsWherePlane(ground, groundpoint);

            if (addDebugObjects) {
                Sphere help = new Sphere(8, 8, 0.2f);
                helper = new Geometry("helper", help);
                Material mathelper = mat.clone();
                mathelper.setColor("Color", ColorRGBA.Red);
                mathelper.setColor("GlowColor", ColorRGBA.Magenta);
                helper.setMaterial(mathelper);
                helper.center().move(groundpoint);
                rootNode.attachChild(helper);
                System.out.println("Clicked: x=" + groundpoint.x + "; y=" + groundpoint.z);
            }

            float laserlength = attackRange;

            CollisionResults collsions = new CollisionResults();
            click3d = new Vector3f(player.getLocalTranslation());
            dir = groundpoint.subtract(click3d).normalizeLocal();
            click3d.y = 3;
            ray = new Ray(click3d, dir);
            ray.setLimit(attackRange);
            enemy.collideWith(ray, collsions);
            if (collsions.size() > 0) {
                float enemyhealth = (Float) enemy.getUserData("health");
                enemy.setUserData("health", enemyhealth - laserdamage);
                laserlength = player.getLocalTranslation().distance(enemy.getLocalTranslation());
            }

            Cylinder laser = new Cylinder(4, 8, 0.02f, laserlength);
            playerLaserBeam = new Geometry("laserbeam", laser);
            Material matlaser = mat.clone();
            matlaser.setColor("Color", ColorRGBA.Orange);
            matlaser.setColor("GlowColor", ColorRGBA.Red);
            playerLaserBeam.setMaterial(matlaser);

// attach laserbeam to player so it moves with player
player.attachChild(playerLaserBeam);
// center laserbeam on players origin
playerLaserBeam.center();
// make the laserbeam point towards clicked spot
playerLaserBeam.lookAt(groundpoint, Vector3f.UNIT_Z);
// move laserbeam up so it does not shoot on ground level, but from player model
playerLaserBeam.move(new Vector3f(0, 3, 0));
// move laserbeam forward because cylinder is created with center at player origin
playerLaserBeam.move(playerLaserBeam.getLocalRotation().mult(new Vector3f(0, 0, laserlength / 2)));
playerLaserLifetime = lasermaxlifetime;

        }
    }
}

[/java]

Baiscaly you have to decide from where you want to shoot the ray, for that you could attach a node without any geometry to your model with a specific name, then you can get it by its name and use its position.
For the direction, well that depends where you want to shoot the ray at. If just in the same direction as the model than you can use its rotation, if its where you clicked you have to get the direction from the clicked point and the position of the node like in the example above.

Edit: Full code.