Rigidbody.ClosestPointOnBounds

説明

アタッチされたコライダーのバウンディングボックスにもっとも近い位置

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public float hitPoints = 10.0F;
    public Rigidbody rb;
    void Start() {
        rb = GetComponent<Rigidbody>();
    }
    void ApplyDamage(Vector3 explosionPos, float radius) {
        Vector3 closestPoint = rb.ClosestPointOnBounds(explosionPos);
        float distance = Vector3.Distance(closestPoint, explosionPos);
        float damage = 1.0F - Mathf.Clamp01(distance / radius);
        damage *= 10;
        hitPoints -= damage;
    }
}