How can I make this sprite cull at the nearest wall?

Im working on a build-engine style unity game, and something regarding my explosion sprites has really been bugging me. My map is split into several pieces for both occlusion culling and my method for dimming certain sections. I want this explosion sprite to only render up until the nearest wall to its left and right, I thought that maybe sprite masks would work but I can't think of any way to implement this in code.