Untiy网格编程篇(一)包围盒效果

Untiy网格编程篇（一）包围盒效果（纯代码，网格实现）
==转载标明出处==

1.效果图：
选中不同的模型，会标识出包围盒的效果

2.实现思路：

第一步：计算模型的AABB包围盒;
第二步：利用包围盒尺寸，获取包围盒的八个顶点，然后对每个顶点三个方向延长线上的顶点,绘制时可以绘制面，但是绘制柱体效果更好，本文为绘制柱体
第三步：设置网格顶点和网格的三角面
第四步：得到上图的效果

3.代码部分：

using UnityEngine;
using System.Collections.Generic;

namespace MeshTools
{
//利用RequireComponent特性，添加实现效果所需要的组件
[RequireComponent(typeof(MeshFilter),typeof(MeshRenderer))]
public class BoundEffect : Monobehaviour
{
private Mesh _mesh = null; 
private MeshFilter _meshFilter = null;
private flaot _lineLenght = 0.25f; //线条长度
private float _lineWidth = 0.025f; //线条宽度
private Bounds _bounds ; //要模拟的包围盒
private Vector3 _boundsPosition; //包围盒的实际位置

//这里是需要添加包围盒特表的模型
private Transform _target = null;
public Transform Target
{
    get { return _target;}
    set
    {
        if (value == _target) return;
        _target = value;
        // 这里需要计算组合模型的包围盒 可以参照我的另一篇博客Bounds(包围盒)概述与AABB包围盒应用
        //http://blog.csdn.net/qq_29579137/article/details/70502591
        //里面有关于BOUNDS()的拓展方法的详细代码与其他使用方式
        //_bounds = value.BOUNDS();
        _bounds = value.GetComponent().bounds;
        _boundsPosition = value.position;
        Refresh();
    }
}

//初始化组件信息
private void Start() 
{
    _meshFilter = this.GetComponent();
    _mesh = new Mesh { name = "BoundEffect" };
    _meshFilter.mesh = _mesh;
} 

/// 

/// 包围盒大小，以及包围盒位置
/// 
/// 
/// 
public void SetEffect( Bounds bounds ,Vector3 boundsPosition )
{
    _bounds = bounds;
    _boundsPosition = boundsPosition;
    Refresh();
}

//绘制网格的方法
private void Refresh()
{
    //初始化包围盒位置
    InitPosition();
    //获取包围盒的八个顶点,按续存储到List
    List vertexList = new List();
    Vector3 unit = _bounds.extents;
           float xLenght = unit.x;
    float yLenght = unit.y;
    float zLenght = unit.z;
    vertexList.Add(new Vector3(xLenght , yLenght , zLenght));
    vertexList.Add(new Vector3(xLenght , yLenght , -zLenght));
    vertexList.Add(new Vector3(xLenght , -yLenght , zLenght));
    vertexList.Add(new Vector3(xLenght , -yLenght , -zLenght));
    vertexList.Add(new Vector3(-xLenght , yLenght , zLenght));
    vertexList.Add(new Vector3(-xLenght , yLenght , -zLenght));
    vertexList.Add(new Vector3(-xLenght , -yLenght , zLenght));
    vertexList.Add(new Vector3(-xLenght , -yLenght , -zLenght));

    //计算每个顶点向其他三个方向延伸的三个顶点，并将它们记录到字典中
    Dictionary> children = new Dictionary>();
    for ( int i = 0 ; i < vertexList.Count ; i++ )
    {
           Vector3 vertex = vertexList[i];
    //计算延伸的顶点
           List childVertexs = new List
           {
                vertex + new Vector3(-vertex.x/Mathf.Abs(vertex.x) * _lineLenght, 0, 0),
                    vertex + new Vector3(0, -vertex.y/Mathf.Abs(vertex.y) * _lineLenght, 0),
                    vertex + new Vector3(0, 0, -vertex.z/Mathf.Abs(vertex.z) * _lineLenght)
           };
           children.Add(i , childVertexs);
    }

    // 初始化网格数据,计算每个角上三个长方体八个顶点的位置，并加入vertexs中
    List vertexs = new List();
    //三角面数量的计算 每个长方体12个三角面,36个三角面的点，一共 8*3*36 
    int[] triangle = new int[8 * 3 * 36];
    //根据线条宽度换算成半径数值
    float lineUnit = _lineWidth / 2.0f;
    for ( int i = 0 ; i < children.Count ; i++ )
     {
            Vector3 center = vertexList[i];
            List childs = children[i];
            //按序号取出延伸点进行长方体顶点的计算
            for ( int j = 0 ; j < childs.Count ; j++ )
            {
                if ( j.Equals(0) )
                        vertexs.AddRange(getVertexsBy2Point(center + new Vector3(center.x / Mathf.Abs(center.x) * lineUnit , 0 , 0) , childs[j] , "X"));
                if ( j.Equals(1) )
                            vertexs.AddRange(getVertexsBy2Point(center + new Vector3(0 , center.y / Mathf.Abs(center.y) * lineUnit , 0) , childs[j] , "Y"));
                if ( j.Equals(2) )
                            vertexs.AddRange(getVertexsBy2Point(center + new Vector3(0 , 0 , center.z / Mathf.Abs(center.z) * lineUnit) , childs[j] , "Z"));
            }
     }
    // 设置三角面顶点序号 分为六个面，共十二个三角面分别赋值
    // 详细原理可以去了解三角面的渲染原理
    for ( int i = 0, count = 0 ; count < triangle.Length ; i += 8, count += 36 )
     {
            triangle[count + 0] = i + 0;
            triangle[count + 1] = i + 2;
            triangle[count + 2] = i + 1;
            triangle[count + 3] = i + 0;
            triangle[count + 4] = i + 3;
            triangle[count + 5] = i + 2;

            triangle[count + 6] = i + 4;
            triangle[count + 7] = i + 5;
            triangle[count + 8] = i + 7;
            triangle[count + 9] = i + 5;
            triangle[count + 10] = i + 6;
            triangle[count + 11] = i + 7;

            triangle[count + 12] = i + 0;
            triangle[count + 13] = i + 1;
            triangle[count + 14] = i + 5;
            triangle[count + 15] = i + 0;
            triangle[count + 16] = i + 5;
            triangle[count + 17] = i + 4;

            triangle[count + 18] = i + 1;
            triangle[count + 19] = i + 2;
            triangle[count + 20] = i + 6;
            triangle[count + 21] = i + 1;
            triangle[count + 22] = i + 6;
            triangle[count + 23] = i + 5;

            triangle[count + 24] = i + 2;
            triangle[count + 25] = i + 3;
            triangle[count + 26] = i + 7;
            triangle[count + 27] = i + 2;
            triangle[count + 28] = i + 7;
            triangle[count + 29] = i + 6;

            triangle[count + 30] = i + 3;
            triangle[count + 31] = i + 0;
            triangle[count + 32] = i + 4;
            triangle[count + 33] = i + 3;
            triangle[count + 34] = i + 4;
            triangle[count + 35] = i + 7;
     }

    // 最后设置网格的顶点和三角面
     _mesh.vertices = vertexs.ToArray();
     _mesh.triangles = triangle;
    }

    //初始化包围盒位置
    private void InitPosition()
    {
    transform.position = _boundsPotision + _bounds.center;
    }

    //通过两点计算出长方体的八个顶点
    private List getVertexsBy2Point( Vector3 first ,Vector3 second , string axis )
    {
        List vertexs = new List();
        float lineUnit = _lineWidth / 2.0f;
       switch (axis)
            {
                case "X":
                    vertexs.Add(first + new Vector3(0 , lineUnit , lineUnit));
                    vertexs.Add(first + new Vector3(0 , lineUnit , -lineUnit));
                    vertexs.Add(first + new Vector3(0 , -lineUnit , -lineUnit));
                    vertexs.Add(first + new Vector3(0 , -lineUnit , lineUnit));
                    vertexs.Add(second + new Vector3(0 , lineUnit , lineUnit));
                    vertexs.Add(second + new Vector3(0 , lineUnit , -lineUnit));
                    vertexs.Add(second + new Vector3(0 , -lineUnit , -lineUnit));
                    vertexs.Add(second + new Vector3(0 , -lineUnit , lineUnit));
                    return vertexs;
                case "Y":
                    vertexs.Add(first + new Vector3(lineUnit , 0 , lineUnit));
                    vertexs.Add(first + new Vector3(lineUnit , 0 , -lineUnit));
                    vertexs.Add(first + new Vector3(-lineUnit , 0 , -lineUnit));
                    vertexs.Add(first + new Vector3(-lineUnit , 0 , lineUnit));
                    vertexs.Add(second + new Vector3(lineUnit , 0 , lineUnit));
                    vertexs.Add(second + new Vector3(lineUnit , 0 , -lineUnit));
                    vertexs.Add(second + new Vector3(-lineUnit , 0 , -lineUnit));
                    vertexs.Add(second + new Vector3(-lineUnit , 0 , lineUnit));
                    return vertexs;
                case "Z":
                    vertexs.Add(first + new Vector3(lineUnit , lineUnit , 0));
                    vertexs.Add(first + new Vector3(lineUnit , -lineUnit , 0));
                    vertexs.Add(first + new Vector3(-lineUnit , -lineUnit , 0));
                    vertexs.Add(first + new Vector3(-lineUnit , lineUnit , 0));
                    vertexs.Add(second + new Vector3(lineUnit , lineUnit , 0));
                    vertexs.Add(second + new Vector3(lineUnit , -lineUnit , 0));
                    vertexs.Add(second + new Vector3(-lineUnit , -lineUnit , 0));
                    vertexs.Add(second + new Vector3(-lineUnit , lineUnit , 0));
                    return vertexs;
                default:
                    return vertexs;
            }
        }
    }
}

4.总结：

1.以上提供两种设置效果的方法，直接赋值Target 或者 调用SetEffect()；
2.包围盒的效果可根据线条的长度和宽度进行设置，也可以动态的根据包围盒的比例进行计算设置获取更好的显示效果；包围盒计算可以参照我的另一篇博客http://blog.csdn.net/qq_29579137/article/details/70502591
3.在添加了MeshRenderer的组件之后，要为MeshRenderer添加材质(新建一个材质球赋值即可),并且可以设置材质球的颜色来确定包围盒效果的颜色；
4.设置Mesh时没有设置uv值和法线值，是因为不设置看起来融合的更加统一，设置了就会以长方体的样式渲染，存在面重合等多种问题；
5.组合模型要实现以上效果需要动过代码计算组合模型,关于组合模型的包围盒计算，在以后的文章中进行讲述。

==代码可以直接运行==
==转载标明出处==