检测哪些切片地图像元与Unity中的Collider2D发生冲突

问题描述

我有一个Tilemap。它有一个TilemapCollider2D组件。上面画着几个瓷砖，每个瓷砖都有自己的精灵对撞机形状。然而，它们是精灵瓷砖，不是预制板。(它们不是使用预制画笔绘制的。)

我还有一个游戏对象，Collider2D(在我的情况下是CircleCollider2D)，isTrigger设置为true，没有附加Rigidbody2D，因为该游戏对象保持在相对于其父对象的固定位置。

[编辑：我发现这个对撞机实际上使用的是父游戏对象的Rigidbody2D。如果没有刚体，则根本检测不到碰撞。]

当Collider2D进入/退出磁贴时，我如何识别该磁贴的网格坐标(Vector3Int)？

例如，在下图中，我希望收到磁贴B、C、D和E的OnTriggerEnter2D()，并知道它们在网格中的位置。

推荐答案

由于此问题不仅涉及Collider2D和TilemapCollider2D之间的冲突，而且还涉及Collider2D和每个瓷砖之间的冲突，因此检测碰撞器之间的冲突并不那么简单。

(Simple detection of collision between the colliders is covered in this question on answers.unity.com.)

为了让tiemap脚本检测到每个磁贴的进入和退出，它需要响应OnTriggerEnter2D()、OnTriggerStay2D()&；OnTriggerExit2D()。

概述

在OnTriggerEnter2D()中，获取CircleCollider2D的边界框并从中标识它与哪些磁贴相交。

在OnTriggerStay2D()中，执行与OnTriggerEnter2D()相同的操作，但从跟踪列表中删除不再相交的磁贴并处理其相交出口。

在OnTriggerExit2D()内，两个对撞器已分离，因此处理跟踪列表中所有磁贴的交集出口并清除跟踪列表。

代码示例

using System.Collections;
using System.Collections.Generic;
using System.Linq; // needed for cloning the list with .ToList()
using UnityEngine;
using UnityEngine.Tilemaps; // needed for Tilemap

public class MyTilemapScript : MonoBehaviour
{
    List<Vector3Int> trackedCells;
    Tilemap tilemap;
    GridLayout gridLayout;

    void Awake()
    {
        trackedCells = new List<Vector3Int>();
        tilemap = GetComponent<Tilemap>();
        gridLayout = GetComponentInParent<GridLayout>();
    }

    void OnTriggerEnter2D(Collider2D other)
    {
        // NB: Bounds cannot have zero width in any dimension, including z
        var cellBounds = new BoundsInt(
            gridLayout.WorldToCell(other.bounds.min),
            gridLayout.WorldToCell(other.bounds.size) + new Vector3Int(0, 0, 1));

        IdentifyIntersections(other, cellBounds);
    }

    void OnTriggerStay2D(Collider2D other)
    {
        // Same as OnTriggerEnter2D()
        var cellBounds = new BoundsInt(
            gridLayout.WorldToCell(other.bounds.min),
            gridLayout.WorldToCell(other.bounds.size) + new Vector3Int(0, 0, 1));

        IdentifyIntersections(other, cellBounds);
    }

    void OnTriggerExit2D(Collider2D other)
    {
        // Intentionally pass zero size bounds
        IdentifyIntersections(other, new BoundsInt(Vector3Int.zero, Vector3Int.zero));
    }

    void IdentifyIntersections(Collider2D other, BoundsInt cellBounds)
    {
        // Take a copy of the tracked cells
        var exitedCells = trackedCells.ToList();

        // Find intersections within cellBounds
        foreach (var cell in cellBounds.allPositionsWithin)
        {
            // First check if there's a tile in this cell
            if (tilemap.HasTile(cell))
            {
                // Find closest world point to this cell's center within other collider
                var cellWorldCenter = gridLayout.CellToWorld(cell);
                var otherClosestPoint = other.ClosestPoint(cellWorldCenter);
                var otherClosestCell = gridLayout.WorldToCell(otherClosestPoint);

                // Check if intersection point is within this cell
                if (otherClosestCell == cell)
                {
                    if (!trackedCells.Contains(cell))
                    {
                        // other collider just entered this cell
                        trackedCells.Add(cell);

                        // Do actions based on other collider entered this cell
                    }
                    else
                    {
                        // other collider remains in this cell, so remove it from the list of exited cells
                        exitedCells.Remove(cell);
                    }
                }
            }
        }

        // Remove cells that are no longer intersected with
        foreach (var cell in exitedCells)
        {
            trackedCells.Remove(cell);

            // Do actions based on other collider exited this cell
        }
    }
}

FYI

From a separate discussion on forum.unity.com，我学到了几个要点(对我来说并不明显)：