Transform.forward

설명

The blue axis of the transform in world space.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public float thrust;
    public Rigidbody rb;
    void Start() {
        rb = GetComponent<Rigidbody>();
    }
    void Update() {
        rb.AddForce(transform.forward * thrust);
    }
}

Another example:

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public float angleBetween = 0.0F;
    public Transform target;
    void Update() {
        Vector3 targetDir = target.position - transform.position;
        angleBetween = Vector3.Angle(transform.forward, targetDir);
    }
}