U_框选 UI

屏幕框选效果

using System.Collections.Generic;
using UnityEngine;

public class SelectionManager : MonoBehaviour {
    // 框选 UI
    public RectTransform selectionScreenCube;
    // 延迟时间
    public float delay;
    // 是否长按
    public bool isLongClicked = false;

    private float btnDownTime;
    private Vector3 clickPos;

    private void Update() {
        GetInput();
        Interact();
    }

    private void GetInput() {
        if (Input.GetMouseButtonDown(0)) {
            // 按下时间
            btnDownTime = Time.realtimeSinceStartup;
            // 点击起始位置
            clickPos = Input.mousePosition;
        }

        if (Input.GetMouseButton(0)) {
            // 延迟时间
            if (Time.realtimeSinceStartup > btnDownTime + delay) {
                isLongClicked = true;
            }
        }

        if (Input.GetMouseButtonUp(0)) {
            selectionScreenCube.gameObject.SetActive(false);
            btnDownTime = 0;
            isLongClicked = false;
        }
    }

    private void Interact() {
        if (isLongClicked) {
            DrawSelect();
        }
    }

    private void DrawSelect() {
        if (!selectionScreenCube.gameObject.activeInHierarchy) {
            selectionScreenCube.gameObject.SetActive(true);
        }

        var nowPos = Input.mousePosition;
        var sizeX = Mathf.Abs(clickPos.x - nowPos.x);
        var sizeY = Mathf.Abs(clickPos.y - nowPos.y);
        // UI 位置
        selectionScreenCube.position = (clickPos + nowPos) / 2f;
        // UI 大小
        selectionScreenCube.sizeDelta = new Vector2(sizeX, sizeY);
    }
}