Prevent projector from projecting through walls

Unity Engine
1

Hi,

I want to project an image onto some walls. Here the problem is that a projector also projects the image onto walls that are actually “shadowed” by another one (i.e. the backside of a wall). Indeed, I could assign each wall to a different layer but this wouldn’t work for floor or backsides. Also adjusting the far clipping plane cannot solve the problem because there may be situations where a point of a concealed wall is nearer than the farthest points of a projected one.
Also using deferredDecals prevent from through-wall-projection.

Is there any way to prevent the projector from projecting through walls?

Thanks

2

One possible solution I found is to use 3 lights with red, green and blue lights with light cookies containing the values of each color-channel in alpha-channel. Nevertheless, since my textures change multiple times per second for many projectors and there are many more computations to do, the splitting of the channels in different textures is to expensive and would heavily drop down the framerate.
Are there any other ideas?