Game_CodeMM/Assets/00_scripts/MapScripts/MapBuildPlacer.cs

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class MapBuildPlacer : MonoBehaviour
{
    [HideInInspector] public GameObject startPositionObject; // 坐标起始点
    [HideInInspector] public float cellSize = 2; // 单元格大小
    [HideInInspector] public Camera mainCamera;
    [Tooltip("可建造格子的图层")] public LayerMask buildableCellLayer;

    private Color sprite_render_color;
    private SpriteRenderer sprite_render_children;
    private MapBuildableCell adsorb_component;
    private bool is_trigger_with_has_build = false;
    private SpriteRenderer stopUI_sprite_render;
    private bool isSnap = false;
    private GameObject render_container;

    private void Start()
    {
        render_container = transform.Find("RenderContainer").gameObject;
        sprite_render_children = transform.Find("RenderContainer/RoomSpriteRender").GetComponent<SpriteRenderer>();
        sprite_render_color = sprite_render_children.color;
        stopUI_sprite_render = transform.Find("RenderContainer/UI/StopUI").GetComponent<SpriteRenderer>();
    }

    private void Update()
    {
        self_move_with_mouse_with_ray();
        self_set_snap_response();
    }

    private void self_set_snap_response()
    {
        render_container.SetActive(isSnap);
    }

    // 跟随鼠标移动使用射线检测
    private void self_move_with_mouse_with_ray()
    {
        Vector3 mouse_world_position = mainCamera.ScreenToWorldPoint(Input.mousePosition);
        mouse_world_position.z = 0;
        RaycastHit2D hit = Physics2D.Raycast(
            origin: mouse_world_position,
            direction: Vector2.zero,
            distance: 0.1f,
            layerMask: buildableCellLayer);
        if (hit.collider)
        {
            // 吸附到格子坐标
            adsorb_component = hit.collider.GetComponent<MapBuildableCell>();
            Vector3 adsorb_position = startPositionObject.transform.position +
                                      adsorb_component.m_get_grid_position_with_vector3() * cellSize;
            transform.position = adsorb_position;
            isSnap = true;
            // 判断是否与以建造的建筑物触发器接触
            if (is_trigger_with_has_build == false)
            {
                sprite_render_children.color = sprite_render_color;
                stopUI_sprite_render.enabled = false;
            }
        }
        else
        {
            // 鼠标不在格子上时触发, 还原默认状态
            if (adsorb_component)
            {
                stopUI_sprite_render.enabled = true;
                adsorb_component = null;
            }

            isSnap = false;
            transform.position = mouse_world_position;
            sprite_render_children.color = new Color32(166, 73, 73, 215);
        }
    }


    public bool m_get_placer_is_snap() => isSnap;

    // trigger 
    private void self_on_trigger_event(Collider2D other, bool status)
    {
        // 检测是否与某个图层的碰撞器相交
        if (other.gameObject.layer == LayerMask.NameToLayer("AlreadyBuild"))
        {
            is_trigger_with_has_build = status;
        }
    }

    private void OnTriggerStay2D(Collider2D other)
    {
        self_on_trigger_event(other, true);
    }

    private void OnTriggerEnter2D(Collider2D other)
    {
        self_on_trigger_event(other, true);
    }

    private void OnTriggerExit2D(Collider2D other)
    {
        self_on_trigger_event(other, false);
    }
}