橡皮擦实现和拖拽绘制

我们需要让我们的编辑器支持两种模式，一种是Draw模式，一种是Erase模式

添加编辑模式

我们使用枚举来指定模式

修改LevelEditor脚本

using System;
using UnityEngine;

namespace ShootingEditor2D
{
    public class LevelEditor : MonoBehaviour
    {
        public enum OperateMode
        {
            Draw,
            Erase
        }
        OperateMode mCurrentOperateMode;
        //...
        Lazy<GUIStyle> mModeLableStyle = new Lazy<GUIStyle>(() => 
        { 
            return new GUIStyle(GUI.skin.label)
            {
                fontSize = 30,
                alignment = TextAnchor.MiddleCenter
            }; 
        });
        private void OnGUI()
        {
            var modeLabelRect = RectHelper.RectForAnchorCenter(Screen.width * 0.5f, 35, 300, 50);
            GUI.Label(modeLabelRect,mCurrentOperateMode.ToString(),mModeLableStyle.Value);
        }
        //...

}

我们再添加两个Button，用来切换绘制模式

using System;
using UnityEngine;

namespace ShootingEditor2D
{
    public class LevelEditor : MonoBehaviour
    {
        public enum OperateMode
        {
            Draw,
            Erase
        }
        OperateMode mCurrentOperateMode;
        //...

        Lazy<GUIStyle> mModeLableStyle = new Lazy<GUIStyle>(() => 
        { 
            return new GUIStyle(GUI.skin.label)
            {
                fontSize = 30,
                alignment = TextAnchor.MiddleCenter,
            }; 
        });
        Lazy<GUIStyle> mButtonStyle = new Lazy<GUIStyle>(() =>
        {
            return new GUIStyle(GUI.skin.button)
            {
                fontSize = 30,
            };
        });
        private void OnGUI()
        {
            var modeLabelRect = RectHelper.RectForAnchorCenter(Screen.width * 0.5f, 35, 300, 50);
            GUI.Label(modeLabelRect,mCurrentOperateMode.ToString(),mModeLableStyle.Value);

            var drawButtonRect = new Rect(10, 10, 150, 50);
            if (GUI.Button(drawButtonRect, "Draw", mButtonStyle.Value))
            {
                mCurrentOperateMode = OperateMode.Draw;
            }
            var eraseButtonRect = new Rect(10, 60, 150, 50);
            if (GUI.Button(eraseButtonRect, "Erase", mButtonStyle.Value))
            {
                mCurrentOperateMode = OperateMode.Erase;
            }
        }
        //...
    }
}

实现模式切换功能

首先修改高亮块的颜色提示部分

修改LevelEditor脚本的Update里面的部分代码块

if (Mathf.Abs(EmptyHighlight.transform.position.x - mouseWorldPos.x) < 0.1f && 
    Mathf.Abs(EmptyHighlight.transform.position.y - mouseWorldPos.y) < 0.1f)
{

}
else
{
    EmptyHighlight.transform.position = mouseWorldPos - new Vector3(0,0,1);
    Ray ray = Camera.main.ScreenPointToRay(mousePosition);

    RaycastHit2D hit = Physics2D.Raycast(ray.origin, Vector2.zero,20);

    if (hit.collider)
    {
        if (mCurrentOperateMode == OperateMode.Draw)
        {
            EmptyHighlight.color = new Color(1, 0, 0,0.5f);
        }else if (mCurrentOperateMode == OperateMode.Erase)//橡皮擦模式下显示橙色
        {
            EmptyHighlight.color = new Color(1, 0.5f, 0, 0.5f);
        }

        mCanDraw = false;
    }
    else
    {
        if (mCurrentOperateMode == OperateMode.Draw)
        {
            EmptyHighlight.color = new Color(1, 1, 1, 0.5f);
        }else if(mCurrentOperateMode == OperateMode.Erase)//橡皮擦模式下显示蓝色
        {
            EmptyHighlight.color = new Color(0, 0, 1, 0.5f);
        }
        mCanDraw = true;
    }
}

然后修改绘制逻辑

using System;
using UnityEngine;

namespace ShootingEditor2D
{
    public class LevelEditor : MonoBehaviour
    {
        
        //...

        private GameObject mCurrentObjectMouseOn;//缓存当前鼠标下的物体

        //...
        
        void Update()
        {
            //...
            if (Mathf.Abs(EmptyHighlight.transform.position.x - mouseWorldPos.x) < 0.1f && 
                Mathf.Abs(EmptyHighlight.transform.position.y - mouseWorldPos.y) < 0.1f)
            {

            }
            else
            {
                //...
                if (hit.collider)
                {
                    //...
                    mCurrentObjectMouseOn = hit.collider.gameObject;//获得物体
                }
                else
                {
                    //...
                    mCurrentObjectMouseOn = null;
                }
            }
            if (Input.GetMouseButtonDown(0))
            {
                if (mCanDraw && mCurrentOperateMode == OperateMode.Draw)
                {
                    var groundPrefab = Resources.Load<GameObject>("Ground");
                    var groundGameObj = Instantiate(groundPrefab,transform);
                    groundGameObj.transform.position = mouseWorldPos;
                    groundGameObj.name = "Ground";
                    mCanDraw = false;
                }else if(mCurrentObjectMouseOn && mCurrentOperateMode == OperateMode.Erase)//擦除物体
                {
                    Destroy(mCurrentObjectMouseOn);
                    mCurrentObjectMouseOn = null;
                }
            }
        }
    }
}

防止点选GUI按钮时发生绘制

使用GUIUtility.hotControl来判断当前鼠标是否和GUI发生了交互，它返回一个int值，代表交互数量。

修改LevelEditor脚本，

void Update()
{
    //...
    mouseWorldPos.y = Mathf.Floor(mouseWorldPos.y + 0.5f);

    if(GUIUtility.hotControl == 0)//鼠标在GUI上时，高亮块就不显示
    {
        EmptyHighlight.gameObject.SetActive(true);
    }
    else
    {
        EmptyHighlight.gameObject.SetActive(false);
    }

    //...
    if (Input.GetMouseButtonDown(0) && GUIUtility.hotControl == 0)//增加判断GUI交互的条件
    {
        if (mCanDraw && mCurrentOperateMode == OperateMode.Draw)
        {
            var groundPrefab = Resources.Load<GameObject>("Ground");
            var groundGameObj = Instantiate(groundPrefab,transform);
            groundGameObj.transform.position = mouseWorldPos;
            groundGameObj.name = "Ground";
            mCanDraw = false;
        }else if(mCurrentObjectMouseOn && mCurrentOperateMode == OperateMode.Erase)
        {
            Destroy(mCurrentObjectMouseOn);
            mCurrentObjectMouseOn = null;
        }
    }
}

实现拖拽绘制

方法很简单，我们在绘制的时候加上鼠标长按状态的判断即可

修改LevelEditor脚本

if ((Input.GetMouseButtonDown(0) || Input.GetMouseButton(0)) && GUIUtility.hotControl == 0)//在前面的括号内添加判断
{
    if (mCanDraw && mCurrentOperateMode == OperateMode.Draw)
    {
        var groundPrefab = Resources.Load<GameObject>("Ground");
        var groundGameObj = Instantiate(groundPrefab,transform);
        groundGameObj.transform.position = mouseWorldPos;
        groundGameObj.name = "Ground";
        mCanDraw = false;
    }else if(mCurrentObjectMouseOn && mCurrentOperateMode == OperateMode.Erase)
    {
        Destroy(mCurrentObjectMouseOn);
        mCurrentObjectMouseOn=null;
    }
}