屏幕坐标点转UGUI坐标【包含屏幕适配】

using UnityEngine;

public class ScreenToUI : MonoBehaviour
{
    public const float UI_Width = 1366f;
    public const float UI_Height = 768f;

    public readonly static float Screen_Width_Half = Screen.width / 2f;
    public readonly static float Screen_Height_Half = Screen.height / 2f;

    public readonly static float Screen_UI_Ratio = UI_Width / UI_Height;
    public readonly static float Screen_Screen_Ratio = Screen.width / Screen.height;

    public readonly static float Screen_Width_Ratio = UI_Width / Screen.width;
    public readonly static float Screen_Height_Ratio = UI_Height / Screen.height;

    private Vector3 m_position_offset;

    private void Awake()
    {
        m_position_offset = Vector3.zero;

        //计算目标偏移量，遍历到以中心为锚点的父物体为止
        Transform target = transform;

        int index = 0, count = 0;

        while (target != null)
        {
            if (index++ < count)
            {
                m_position_offset += target.localPosition;

                target = target.parent;
            }
            else
            {
                break;
            }
        }
    }

    private void Update()
    {
        if (Input.GetMouseButton(0))
        {
            Vector3 position = FormatPosition(Input.mousePosition);

            //do something...

            Debug.LogError(position);
        }
    }

    private Vector3 FormatPosition(Vector3 position)
    {
        float ratio_width = 1, ratio_height = 1;

        if (Screen_UI_Ratio != Screen_Screen_Ratio)
        {
            if (Screen_UI_Ratio < Screen_Screen_Ratio)
            {
                float real = Screen.height * Screen_UI_Ratio;
                ratio_width = Screen.width / real;
            }
            else
            {
                float real = Screen.width / Screen_UI_Ratio;
                ratio_height = Screen.height / real;
            }
        }

        position.x -= Screen_Width_Half;
        position.y -= Screen_Height_Half;

        position.x *= Screen_Width_Ratio * ratio_width;
        position.y *= Screen_Height_Ratio * ratio_height;

        position -= m_position_offset;

        return position;
    }
}

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屏幕坐标以左下角为坐标

UGUI以中心为坐标

首先将坐标位置转换

然后通过屏幕宽高比与UGUI设置的宽高比进行计算，UGUI.UIScaleMode = Scale With Screen Size

最后计算父物体与中心点的偏移量