GHZWXWebGL/Assets/TransparentWindow.cs

using System;
using System.Runtime.InteropServices;
using UnityEngine;

public class TransparentWindow : MonoBehaviour
{
    [SerializeField] private Material m_Material;

    private struct MARGINS
    {
        public int cxLeftWidth;
        public int cxRightWidth;
        public int cyTopHeight;
        public int cyBottomHeight;
    }

    [DllImport("user32.dll")]
    private static extern IntPtr GetActiveWindow();

    [DllImport("user32.dll")]
    private static extern int SetWindowLong(IntPtr hWnd, int nIndex, uint dwNewLong);

    [DllImport("Dwmapi.dll")]
    private static extern uint DwmExtendFrameIntoClientArea(IntPtr hWnd, ref MARGINS margins);

    [DllImport("user32.dll", EntryPoint = "SetWindowPos")]
    private static extern int SetWindowPos(IntPtr hwnd, IntPtr hwndInsertAfter, int x, int y, int cx, int cy,
        int uFlags);

    [DllImport("user32.dll")]
    static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);

    [DllImport("user32.dll", EntryPoint = "SetLayeredWindowAttributes")]
    static extern int SetLayeredWindowAttributes(IntPtr hwnd, int crKey, byte bAlpha, int dwFlags);

    [DllImport("User32.dll")]
    private static extern bool SetForegroundWindow(IntPtr hWnd);

    const int GWL_STYLE = -16;
    const int GWL_EXSTYLE = -20;
    const uint WS_POPUP = 0x80000000;
    const uint WS_VISIBLE = 0x10000000;

    const uint WS_EX_TOPMOST = 0x00000008;
    const uint WS_EX_LAYERED = 0x00080000;
    const uint WS_EX_TRANSPARENT = 0x00000020;

    const int SWP_FRAMECHANGED = 0x0020;
    const int SWP_SHOWWINDOW = 0x0040;
    const int LWA_ALPHA = 2;

    private IntPtr HWND_TOPMOST = new IntPtr(-1);

    private IntPtr _hwnd;

    void Start()
    {
#if !UNITY_EDITOR
    MARGINS margins = new MARGINS() { cxLeftWidth = -1 };
    _hwnd = GetActiveWindow();
    int fWidth = Screen.width;
    int fHeight = Screen.height;
        SetWindowLong(_hwnd, GWL_STYLE, WS_POPUP | WS_VISIBLE);
        SetWindowLong(_hwnd, GWL_EXSTYLE, WS_EX_TOPMOST | WS_EX_LAYERED | WS_EX_TRANSPARENT);//若想鼠标穿透，则将这个注释恢复即可
        DwmExtendFrameIntoClientArea(_hwnd, ref margins);
        SetWindowPos(_hwnd, HWND_TOPMOST, 0, 0, fWidth, fHeight, SWP_FRAMECHANGED | SWP_SHOWWINDOW); 
        ShowWindowAsync(_hwnd, 3); //Forces window to show in case of unresponsive app    // SW_SHOWMAXIMIZED(3)
#endif
    }

    void OnRenderImage(RenderTexture from, RenderTexture to)
    {
        Graphics.Blit(from, to, m_Material);
    }
}