Unity-Demo游戏实现桌面小宠物_游戏引擎

看到网上有用unity做的桌面小宠物，就自己搜了些资料自己做了一个小demo。

核心功能实现

简单说一下思路，有一个脚本跟一个shader，通过脚本和shader负责将unity运行时的背景调成透明色。这个是通过调颜色来进行了。具体原理也不清楚，查了查资料大概是这样

‌窗口透明化与无边框‌
- 通过windows api调用setwindowlong和dwmextendframeintoclientarea实现透明背景和隐藏边框，需在相机设置中将clear flags设为solid color且透明度为01。
- 注意：背景色需与模型边缘颜色相近以避免毛边（如0x00bgr格式的colorref值）2。
‌交互逻辑‌
- ‌点击穿透‌：通过检测鼠标坐标与模型碰撞器实现交互（如点击播放挠痒动画）15。
- ‌拖拽限制‌：动态计算模型碰撞器与屏幕边缘距离，使用mathf.clamp限制移动范围2。

代码部分

shader

shader "custom/maketransparent" {
  properties {
    _maintex ("base (rgb)", 2d) = "white" {}
    _transparentcolorkey ("transparent color key", color) = (0,1,0,1)
    _transparencymargin ("transparency margin", float) = 0.01 
  }
  subshader {
    pass {
      tags { "rendertype"="opaque" }
      lod 200
    
      cgprogram

      #pragma vertex vertexshaderfunction
      #pragma fragment pixelshaderfunction
    
      #include "unitycg.cginc"

      struct vertexdata
      {
        float4 position : position;
        float2 uv : texcoord0;
      };

      struct vertextopixeldata
      {
        float4 position : sv_position;
        float2 uv : texcoord0;
      };

      vertextopixeldata vertexshaderfunction(vertexdata input)
      {
        vertextopixeldata output;
        output.position = unityobjecttoclippos (input.position);
        output.uv = input.uv;
        return output;
      }
    
      sampler2d _maintex;
      float3 _transparentcolorkey;
      float _transparencymargin;

      float4 pixelshaderfunction(vertextopixeldata input) : sv_target
      {
        float4 color = tex2d(_maintex, input.uv);
      
        float deltar = abs(color.r - _transparentcolorkey.r);
        float deltag = abs(color.g - _transparentcolorkey.g);
        float deltab = abs(color.b - _transparentcolorkey.b);

        if (deltar < _transparencymargin && deltag < _transparencymargin && deltab < _transparencymargin)
        {
          return float4(0.0f, 0.0f, 0.0f, 0.0f);
        }

        return color;
      }
      endcg
    }
  }
}

c#

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);
    }
}