[游戏开发]Unity屏幕外怪物指示器基于FairyGUI(屏幕边缘指示)笔记

回顾下初中三角函数

** 1，tan(α的弧度) = 对边长b / 领边长a
2，弧度 = 角度 * PI / 180
3，根据Cos,就可以算出CosMax,和CosMin,角度，知道落在什么方位上，如图下图分为8个方位，顺时针**

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

public class UIArrow
{
    // 角度转屏幕边缘落点，基于FairyGUI 计算
    public static Vector2 GetClampPos(float rot)
        float x = 0;
        float y = 0;
        float a = 0;
        float b = 0;
        var w = GRoot.inst.width * 0.5f;
        var h = GRoot.inst.height * 0.5f;
        Vector2 sceneCenter a = new Vector2(w, h);
        var dis = Vector2.Distance(new Vector2(GRoot.inst,width,0), sceneCenter);
        //根据斜边求对角线最大角度 （cosMax + cosMin）= 90°
        var cosMax = Mathf.Acos(h / dis) * Mathf.Rad2Deg;
        var cosMin = Mathf.Acos(w / dis) * Mathf,Rad2Deg;
        // 八个方位顺时针
        if (rot > 0 && rot <= cosMax) // 方位1
        {    
            a = h;
            b = Mathf.Tan(rot * Mathf.PI/180) * a;
            x = w + b;
            y = 0;
        }
        else if (rot > cosMax && rot <= 90) //方位2
        {
            rot = 90 - rot;
            a = w;
            b = Mathf.Tan(rot * Mathf.PI/180) * a;
            x = GRoot.inst.width;
            y = h - b;
        }
        else if (rot > 90 && rot <= 90+cosMin) //方位3
        {
            rot = rot - 90;
            a = w;
            b = Mathf.Tan(rot * Mathf.PI/180) * a
            x = GRoot.inst.width;
            y = h + b;
        }
        else if (rot > 90+cosMin && rot <= 180)//方位4
        {
            rot = 180 - rot;
            a = h;
            b = Mathf.Tan(rot * Mathf.P1/180) * a;
            x = w + b;
            y = GRoot.inst.height;
        }
        else if (rot > 180 && rot <= 180+cosMax)//方位5
        {
            rot = rot - 180;
            a = h;
            b = Mathf.Tan(rot * Mathf.PI/180) * a;
            x = w - b;
            y = GRoot.inst.height;
        }
        else if (rot > 180+cosMax && rot <= 270)//方位6
        {
            rot = 270 - rot;
            a = w;
            b = Mathf.Tan(rot * Mathf.PI/180) * a;
            x = 0;
            y = h + b;
        }
        else 1f (rot > 270 && rot < 270+cosMin) //方位7
        {
            rot =  rot - 270;
            a = w;
            b = Mathf.Tan(rot * Mathf.P1/180) * a;
            x = 0;
            y = h - b;
        }
        else if (rot > 270+cosMin && rot <= 360) //方位8
        {
            rot = 360 - rot;
            a = h;
            b = Mathf.Tan(rot * Mathf.PI/180) * a;
            x = w - b;
            y = 0;
        }
        return new Vector2(x, y);
    }
    //屏幕内
    public static  bool IsInView(Vector3 worldPos)
    {
        Transform camTransform = Camera.main.transform;
        Vector2 viewPos = Camera.main.WorldToViewportPoint(worldPos);
        //判断物体是否在相机前面  
        Vector3 dir = (worldPos - camTransform.position).normalized;
        float dot = Vector3.Dot(camTransform.forward, dir);
        if (dot > 0 && viewPos.x >= 0 && viewPos.x <= 1 && viewPos.y >= 0 && viewPos.y <= 1)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    // 区域内限制
    public static  Vector2 GetClampPos(Vector2 pos)
    {
        Vector2 safePos = Vector2.zero;
        safePos.x = Mathf.Clamp(pos.x, 0, GRoot.inst.width);
        safePos.y = Mathf.Clamp(pos.y, 0, GRoot.inst.height);

        return safePos;
    }

     // rotation
    public static  Vector2 GetClampRot(Vector2 posCenter, Vector2,tarPos)
    {
        var dif = (new Vector2(tarPos.x,tarPos.y) - posCenter).normalized;
        return Quaternion.LookRotation(new Vector3(dif.x, 0, dif.y)).eulerAngles.y;
    }
}

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