unity 模型沿地表移动工具

让模型在地表移动,
目录结构
/assets/editor

using UnityEngine;
using UnityEditor;
using System.Collections;
/// 

/// 模型拖动器
/// 1. 地表.
/// 2. 地图表面.
/// 
public class ModelDragger : EditorWindow
{
    static readonly string INTRODUCE = "让模型沿地表移动.\n"
        +"沿地表:模型的高度为当前地形高度.\n"
        +"沿地图:模型高度为,从上面开始.第一个接触到模型的高度";

    static readonly string MY_NAME = "模型拖动器";
    static readonly string ALONG_TERRAIN = "沿地表拖动:";
    static readonly string ALONG_MAP = "沿地图拖动:";
    static readonly string ON = "开";
    static readonly string OFF = "关";
    static readonly string CANT_MOVE_TERRAIN = "地形,不能移动.";

    private bool isTerrain;
    private bool isMap;
    private Terrain curTerrain;

    [MenuItem("Level4/Fbx/ModelDragger")]
    static void Init()
    {
        ModelDragger md = EditorWindow.GetWindow(false, MY_NAME) as ModelDragger;
        md.curTerrain = Terrain.activeTerrain;
    }

    void OnGUI()
    {
        GUILayout.Label(INTRODUCE);
        //地表
        EditorGUILayout.BeginHorizontal("box");
        EditorGUILayout.PrefixLabel(ALONG_TERRAIN);
        isTerrain = GUILayout.Toggle(isTerrain, isTerrain ? OFF : ON);
        if (isTerrain)
            isMap = false;
        EditorGUILayout.EndHorizontal();
        //地图
        EditorGUILayout.BeginHorizontal("box");
        EditorGUILayout.PrefixLabel(ALONG_MAP);
        isMap = GUILayout.Toggle(isMap, isMap ? OFF : ON);
        if (isMap)
            isTerrain = false;
        EditorGUILayout.EndHorizontal();
    }
    void Update()
    {
        if (isTerrain)
        {
            DragAlongTerrain();
        }
        else if (isMap)
        {
            DragAlongMap();
        }
    }
    /// 

    /// 模型沿地表移动
    /// 
    void DragAlongTerrain()
    {
        if (curTerrain != null)
        {
            foreach (Transform tr in Selection.transforms)
            {
                if (tr.GetComponent() == null)
                    tr.position = new Vector3(tr.position.x, curTerrain.SampleHeight(tr.position), tr.position.z);
                else
                {
                    ShowNotification(new GUIContent(CANT_MOVE_TERRAIN));
                    break;
                }
            }
        }
    }
    /// 

    /// 模型沿地图移动.
    /// 
    void DragAlongMap()
    {
        foreach (Transform tr in Selection.transforms)
        {
            if (tr.GetComponent() == null)
                FallIt(tr);
            else
            {
                ShowNotification(new GUIContent(CANT_MOVE_TERRAIN));
                break;
            }
        }
    }
    /// 

    /// 物体 向下掉落.
    /// 
    /// 
    void FallIt(Transform tr)
    {
        Vector3 origin = tr.position;
        origin.y += 1000;
        Vector3 dir = Vector3.down;
        RaycastHit[] hits = Physics.RaycastAll(origin, dir);
        Debug.DrawRay(origin,dir*100,Color.red);

        foreach (RaycastHit hit in hits)
        {
            if (hit.transform != tr)
            {
                tr.position = hit.point;
                break;
            }
        }
    }
}