Use GrabPass to get a texture with the current pixels in the Frame Buffer that are behind the object. Use ComputeGrabScreenPos to calculate the uvs to use in the grab pass texture. Use tex2Dproj and ...

Create a shader and attach to the upper script in Main Camera, codes in shader: Shader "Custom/TransparentFlipShader" { Properties { _MainTex("Texture", 2D) = "white ...