CODEWITHSUNDEEP
c#unity-game-enginephysicsprojectile
Pawelsar1
Pawelsar1

Reputation: 83

How to calculate the trajectory of bullet in Unity2D?

I'm doing the 2D game with bullets moving in parabola, but before I shoot the projectile I want to be able to calculate its trajectory. 

            float velocity = Mathf.Min(Mathf.Max(distance, 1), 2.5f);
        float cos = Mathf.Cos( (gameObject.transform.localEulerAngles.z + 90) * Mathf.Deg2Rad);
        float sin = Mathf.Sin( (gameObject.transform.localEulerAngles.z + 90) * Mathf.Deg2Rad);
        newGO.GetComponent<Rigidbody2D>().AddForce(velocity * new Vector3(cos, sin))

This code adds the rigidbody2d to my bullet (newGO). I try to count a point after 1 sec of flying using it:

Debug.Log(new Vector3(source.transform.position.x + velocity * 1 * cos, source.transform.position.y + velocity * sin * 1 + Physics2D.gravity.y * 0.5f * 1));

Unfortunately it doesn't return the correct result. What should I do? Thanks for help and sorry for my English.

Upvotes: 1

Views: 1314

Answers (1)

ORParga
ORParga

Reputation: 390

I think being a projectile you should use Rigidbody2D.velocity to set the initial velocity of the projectile rather than Rigidbody2D.AddForce. (Although the documentation does not recommend)

This simple script predicts where the attached object will be in a time determined by the variable "timeLimit" and moves a "target" gameobject to that point.

public class Velocity : MonoBehaviour {

    public GameObject target;

    private float HoriInitialSpeed = 5;
    private float VertInitialSpeed = 5;
    private float timeLimit = 2;
    private float timeElapsed=0;

    void Start ()
    {
        float HoriPredict = HoriInitialSpeed * timeLimit;
        float VertiPredict = VertInitialSpeed* timeLimit + (0.5f * Physics2D.gravity.y * timeLimit * timeLimit);

        target.transform.Translate(HoriPredict, VertiPredict,0);
        GetComponent<Rigidbody2D>().velocity = new Vector2(HoriInitialSpeed, VertInitialSpeed);
    }

    void Update () {
        timeElapsed += Time.deltaTime;
        if(timeElapsed >= timeLimit)
        {
            //stop the bullet
            GetComponent<Rigidbody2D>().velocity = new Vector2(0, 0);
            GetComponent<Rigidbody2D>().gravityScale = 0;
        }
    }
}

Note: the bullet and the target must be in the same point inicially

Upvotes: 2

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