前言

作为碰撞盒的检测，OBB是一个常用的办法。网上有很多文章是介绍原理的，具体可以查一下。 以下给出OBB的Unity实现版本。亲测可跑。

参考 ：

效果

实现

基础：对象拥有BoxCollider控件（用作包围盒）和MeshRenderer控件（模型）

步骤：1.更新BoxCollider 2.更新AABB

更新BoxCollider。这个只需要在编辑器中更新一下即可，不需要运行时不断更新。

using UnityEngine;public class UpdateBoxColliderHelp{    private Transform m_Transform;    private MeshRenderer m_MeshRenderer;    private BoxCollider m_BoxCollider;    public UpdateBoxColliderHelp(Transform transform)    {        m_Transform = transform;        m_MeshRenderer = m_Transform.GetComponent
    
     ();        m_BoxCollider = m_Transform.GetComponent
     
      ();         UpdateBoxCollider();    }    public void UpdateBoxCollider()    {        if (m_MeshRenderer == null || m_BoxCollider == null)        {            Debug.Log(string.Format("对象{0}没有指定控件，跳过。", m_Transform.name));            return;        }        Vector3 position = m_Transform.position;        Vector3 scale = m_Transform.localScale;        Quaternion rotation = m_Transform.rotation;        m_Transform.position = Vector3.zero;        m_Transform.localScale = Vector3.one;        m_Transform.rotation = new Quaternion(0,0,0,1);        m_BoxCollider.size = m_MeshRenderer.bounds.size;        m_BoxCollider.center = m_MeshRenderer.bounds.center;        m_Transform.position = position;        m_Transform.localScale = scale;        m_Transform.rotation = rotation;        Debug.Log(string.Format("对象{0}的BoxCollider更新完毕。", m_Transform.name));    }}复制代码
     
    

OBB的实现

using System;using UnityEngine;public class OBBRect{    public Transform m_Transform;    public BoxCollider m_BoxCollider;    private double m_Rotation;    public Vector2 m_Extents;    public Vector2[] m_Axiss;    public OBBRect(Transform transform)    {        m_Transform = transform;        m_BoxCollider = m_Transform.GetComponent
    
     ();        m_Axiss = new Vector2[2];        SetExtents();    }    private void SetExtents()    {        Quaternion rotation = m_Transform.rotation;        m_Transform.rotation = new Quaternion(0, 0, 0, 1);        Vector3 center = m_BoxCollider.center;        Vector3 size = m_BoxCollider.size / 2;        Vector3 Point1 = new Vector3(center.x + size.x, center.y, center.z - size.z);        Vector3 Point2 = new Vector3(center.x - size.x, center.y, center.z + size.z);        Point1 = m_Transform.localToWorldMatrix.MultiplyPoint3x4(Point1);        Point2 = m_Transform.localToWorldMatrix.MultiplyPoint3x4(Point2);        m_Extents = new Vector2(Mathf.Abs(Point1.x - Point2.x)/2,Mathf.Abs(Point2.z - Point1.z)/2);        m_Transform.rotation = rotation;    }    public float dot(Vector2 a, Vector2 b)    {        return Mathf.Abs(a.x * b.x + a.y * b.y);    }    public float getProjectionRadius(Vector2 axis)    {        return (m_Extents.x * dot(m_Axiss[0], axis) + m_Extents.y * dot(m_Axiss[1], axis));    }    public void Update()    {        m_Rotation = m_Transform.eulerAngles.y * Math.PI / 180;        m_Axiss[0] = new Vector2( (float) Math.Cos(m_Rotation), -(float) Math.Sin(m_Rotation));        m_Axiss[1] = new Vector2(-m_Axiss[0].y, m_Axiss[0].x);    }    public bool intersects(OBBRect other)    {        Update();        other.Update();        Vector2 distanceVector = new Vector2(m_Transform.position.x - other.m_Transform.position.x, m_Transform.position.z - other.m_Transform.position.z);               Vector2[] checkObbVector2s =        {            m_Axiss[0],            m_Axiss[1],            other.m_Axiss[0],            other.m_Axiss[1],        };        for (int index = 0; index < checkObbVector2s.Length; index++)        {            Vector2 curVector2 = checkObbVector2s[index];            if ((getProjectionRadius(curVector2) + other.getProjectionRadius(curVector2)) <= dot(distanceVector, curVector2))            {                return false;            }        }        return true;    }}复制代码
    

注意点

1.先更新包围盒，所有计算（宽高这些）都是基于包围盒的数据。

2.该算法是做到模型忽略Y轴进行检测，需要的话可以自己补充一下。思路:多一个轴向计算。

3.计算Sin值和参考文章不一样，这里是使用-Sin才得到正确的数值。原因我也还没想到。。知道的话麻烦告诉我一下哈哈哈