public static float Dot (Vector3 lhs, Vector3 rhs);

説明

Dot Product of two vectors.

The dot product is a float value equal to the magnitudes of the two vectors multiplied together and then multiplied by the cosine of the angle between them.

For normalized vectors Dot returns 1 if they point in exactly the same direction, -1 if they point in completely opposite directions and zero if the vectors are perpendicular.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { public Transform other; void Update() { if (other) { Vector3 forward = transform.TransformDirection(Vector3.forward); Vector3 toOther = other.position - transform.position; if (Vector3.Dot(forward, toOther) < 0) print("The other transform is behind me!"); } } }