Unity Vector3.Reflect , cant get it to work properly

Question

im kinda new to unity and coding so im sorry for silly mistakes and not using proper language to describe things.

Im trying to make a 2d shooting game where the bullet bounces off the walls like a ricochet . I created a Ray pointing to the direction the bullet is going and then tested if that ray collides with the walls , i had to create a 3d box colliders where the walls are, because ray wouldn't detect 2d collider . Now im trying to use Vector3.reflect to change the rotation of the bullet so it would bounce off like a ricochet but instead its bouncing to random directions and sometimes its going through the box colliders. I just would like to know where is the problem , is it in the code or the scene setup ? if anybody has some advice,tip or even criticism i would appreciate .thanks

here is the code attached to the bullet void Update () {

    Vector3 fwd = transform.TransformDirection(Vector3.up);
    //Debug.DrawRay(raycastObject.transform.position, fwd * raySize, Color.green);

    RaycastHit hit;
    Ray ray = new Ray (transform.position , fwd * raySize ) ;
    Debug.DrawRay (transform.position, fwd * raySize); 

    if (Physics.Raycast (ray , out hit, raySize  )) {
        Debug.Log ("Bouce test 1 ");

                    if (hit.collider.tag == "Wall") {
                            Debug.Log ("Bounce test 2 ");

                            Vector3 reflectDir = Vector3.Reflect (ray.direction , hit.normal);
                            float rot =  Mathf.Atan2 (reflectDir.y, reflectDir.x) * Mathf.Rad2Deg;
                            transform.eulerAngles = new Vector3 (0, 0, rot);

                }

and this is code for movement of the bullet

       Vector3 pos = transform.position; 
       Vector3 velocity = new Vector3 (0, speed * Time.deltaTime, 0); 
       pos += transform.rotation * velocity;
       transform.position = pos;

natS natS · Accepted Answer · 2015-12-11T19:56:15

It looks to me like your issues has to do with the fact that this is a really round about way to go about things where you are working in 3D space, and yet using 2D spacial functions to calculate your transformation, and then finally preforming your rotation in only one dimension (one dimension as far as polar coordinates go, obviously 2 in Cartesian space). For related reasons you already have found that you needed to use the 3D box colliders instead of their 2D cousins to get the results you want. When building with 3D objects, try to stick with 3D functions, and other 3D things. Mixing dimensions is going to make things painfully complicated and will likely result in difficult to read code and problems that become difficult to solve.

Your solution really depends on what you are trying to do with your game. In a fully 3D game piping spacial calculations through various 2D methods is just going to be a recipe for disaster. For an effectively 2D game made up of 3D objects it will still be simpler to program reflecting your Vector using the 3D functions, and if necessary due to 3D geometry sloping out of the field of play, then projecting the result into the 2D plane of play and then normalizing and/or scaling it as necessary.

Assuming no complicating geometry, you should be able to replace this:

Vector3 reflectDir = Vector3.Reflect (ray.direction , hit.normal);
float rot =  Mathf.Atan2 (reflectDir.y, reflectDir.x) * Mathf.Rad2Deg;
transform.eulerAngles = new Vector3 (0, 0, rot);

with this:

Vector3 reflectDir = Vector3.Reflect (ray.direction , hit.normal);
transform.rotation.SetFromToRotation(ray.direction, reflectDir);

Give that a try. If you need to project things in plane afterwards due to sloping 3D geometry let me know, and I'll try to hack something together to fix it up for you.

Unity Vector3.Reflect , cant get it to work properly

3 Answers