Is there a way for shader to get if it's rendering for left/right eye in XR

i am currently working on some advanced effect for VR.

one of it is to use camera’s RenderTexture and render it to the background on a VR view. but the problem is i don’t know how to make the shader to get if it’s rendering for left/right eye in XR. Do you have suggestion for me?

Engine sets camera projection matrices, but nothing extra (no extra uniform that could identify a view):

You could modify the engine, to set uniform with a view index in the code provided above.