Unity中如何让盒子精灵精准落在鼠标点击位置且无倾斜？

我正在开发一个带Canvas的Unity项目，尝试创建盒子对象。盒子能正常创建，但放置时精灵会出现倾斜，效果如下：

现有代码逻辑 #

射线检测与放置触发

用户点击Canvas时，通过相机发射射线获取鼠标位置，命中对象后验证位置并创建盒子：

Ray ray = _camera.ScreenPointToRay(Input.mousePosition);
if(Physics.Raycast(ray, out RaycastHit hitInfo, Mathf.Infinity))
{           
    if (_CheckCanDropObject(ray, hitInfo))
    {
        BuildingController.CreateBox(new Vector3(hitInfo.point.x, hitInfo.point.y, WHConstants.AboveDefaultZ), buildingInventoryController.currentBlock.BlockSprite);
    }
}

盒子创建流程

位置验证通过后，调用CreateBox遍历建筑子对象找到平面图，通过工厂模式创建盒子并添加到命令队列：

public static void CreateBox(Vector3 position, UnityEngine.Sprite sprite)
{
    List<ICommand> commands = new List<ICommand>();
    foreach (CreatorItem child in GetBuilding().children)
    {
        if (child.name.Contains(WHConstants.FLOOR_PLAN))
        {
            CreatorItem floorPlan = child;
            float height = floorPlan.GetComponent<IHasDimension>().Dimension.Height;

            string name = NamingController.GetName(WHConstants.Box, floorPlan.uiItem.Foldout.Children());
            CreatorItemCreateCommand createCommand = new CreatorItemCreateCommand(new CreatorBoxFactory(position, sprite, height), name);
            ICommand createAndAddParentCommand = new CreateCreatorItemWithParentCommand(createCommand, floorPlan.Id);
            commands.Add(createAndAddParentCommand);
        }
    }
    ICommand createBox = new MultipleCommand(commands);
    UndoRedo.AddAndExecuteCommand(createBoxs); // 注意：此处变量名疑似笔误，应为createBox
    DeselectAll();
    CreatorUIController.UnSavedProgress = true;
}

盒子工厂实现

CreatorBoxFactory负责生成盒子GameObject，包含SpriteRenderer和碰撞体：

public class CreatorBoxFactory : ICreatorItemFactory
{
    private Vector3 _position;
    private Sprite _sprite;
    private float _height;

    public CreatorBoxFactory(Vector3 position, Sprite sprite, float height)
    {
        _height = height;
        _position = position;
        _sprite = sprite;
    }

    public CreatorItem Create(string name, bool createGO = true)
    {
        Box item;
        GameObject Box = null;
        if (createGO)
        {
            UIItem uiItem = new BoxUIFactory().Create(name);
            Box = CreateBox();
            item = new Box(Box, uiItem);
        }
        else
        {
            item = new Box(null, null);
        }
        item.SetPosition(new Vector3(_position.x, _position.y, 0));
        item.SetDimension(WHConstants.DefaultBoxLength, _height, WHConstants.DefaultBox2DHeight);
        item.SetName(name);

        if (item.uiItem != null)
        {
            item.uiItem._delegate = item;
        }
        if (createGO)
        {
            item.SetTransformer();
        }
        return item;
    }

    private GameObject CreateBox()
    {
        GameObject boxGameObject = new GameObject();
        SpriteRenderer spriteRenderer = boxGameObject.AddComponent<SpriteRenderer>();
        spriteRenderer.sprite = _sprite;

        Vector2 unit = ConvertCoordinate.PixelToUnit(spriteRenderer.sprite);

        BoxCollider lineCollider = boxGameObject.AddComponent<BoxCollider>();
        lineCollider.transform.parent = spriteRenderer.transform;
        lineCollider.size = new Vector3(unit.x, unit.y, 1f);
        lineCollider.center = new Vector3(0.0f, 0.0f, 0.0f);

        boxGameObject.tag = WHConstants.METABLOCK;

        boxGameObject.transform.position = _position;
        boxGameObject.transform.localScale = new Vector3(WHConstants.DefaultBoxLength / unit.x, WHConstants.DefaultBox2DHeight / unit.y, 1);
        return boxGameObject;
    }
}

问题分析与修复方案 #

倾斜原因排查

1. 父对象旋转继承：盒子被父化到floorPlan对象下，如果floorPlan本身带有旋转角度，盒子会继承该旋转，导致精灵倾斜。
2. 碰撞体父化错误：将BoxCollider挂载到SpriteRenderer子对象上，若SpriteRenderer有旋转/缩放偏移，会带动碰撞体和视觉表现异常。
3. 未明确重置旋转：创建盒子时未强制重置旋转状态，可能继承场景或父对象的默认旋转值。

修复步骤

1. 强制重置盒子旋转：在创建盒子GameObject后，立即重置旋转为无角度状态：

   private GameObject CreateBox()
   {
       GameObject boxGameObject = new GameObject();
       // 重置根对象旋转，避免继承默认或父对象旋转
       boxGameObject.transform.rotation = Quaternion.identity;
       
       SpriteRenderer spriteRenderer = boxGameObject.AddComponent<SpriteRenderer>();
       spriteRenderer.sprite = _sprite;
       // ... 其余代码保持不变
   }
   

2. 修正碰撞体挂载层级：将碰撞体直接挂载在盒子根对象上，避免受SpriteRenderer的变换影响：

   private GameObject CreateBox()
   {
       GameObject boxGameObject = new GameObject();
       boxGameObject.transform.rotation = Quaternion.identity;
       
       SpriteRenderer spriteRenderer = boxGameObject.AddComponent<SpriteRenderer>();
       spriteRenderer.sprite = _sprite;
   
       Vector2 unit = ConvertCoordinate.PixelToUnit(spriteRenderer.sprite);
   
       // 移除lineCollider.transform.parent = spriteRenderer.transform;
       BoxCollider lineCollider = boxGameObject.AddComponent<BoxCollider>();
       lineCollider.size = new Vector3(unit.x, unit.y, 1f);
       lineCollider.center = new Vector3(0.0f, 0.0f, 0.0f);
       
       // ... 其余代码保持不变
   }
   

3. 父化后重置局部旋转：在将盒子父化到floorPlan后，确保盒子的局部旋转为无角度状态（可在CreateCreatorItemWithParentCommand的执行逻辑中添加）：

   // 父化操作完成后添加
   createdItem.transform.localRotation = Quaternion.identity;
   

4. 适配Canvas坐标系（可选）：如果是纯UI Canvas项目，建议使用2D方式获取点击位置，替代3D射线检测，避免坐标系偏差：

   if (Input.GetMouseButtonDown(0))
   {
       if (RectTransformUtility.ScreenPointToLocalPointInRectangle(
           yourCanvasRectTransform, 
           Input.mousePosition, 
           _camera, 
           out Vector2 localPoint))
       {
           Vector3 worldPosition = yourCanvasRectTransform.TransformPoint(localPoint);
           worldPosition.z = WHConstants.AboveDefaultZ;
           if (_CheckCanDropObject(worldPosition))
           {
               BuildingController.CreateBox(worldPosition, buildingInventoryController.currentBlock.BlockSprite);
           }
       }
   }
   

精准定位补充

要确保盒子精准落在鼠标点击位置：

• 检查Sprite导入设置，将Pivot设为中心(0.5,0.5)，保证视觉中心点与对象原点对齐
• 确保点击位置转换时，坐标系保持一致（3D世界空间或Canvas局部空间）
• 避免对创建后的盒子位置进行二次偏移操作

内容的提问来源于stack exchange，提问作者Rasik