I have multiple overlapping water meshes that use a refraction map. Right now my engine doesn't support this scenario. Assuming the geometry does not intersect, one solution I thought of would be just to ping-pong the render target and refraction map, and render the overlapping water features in back-to-front order. I've ping-ponged buffers before. Would this be too expensive? This seems kind of brute force, are there better solutions?