This is ray marching, not ray tracing. Ray marching takes steps through an implicit surface, in this case the depth buffer, while ray tracing does full ray/tria

This is ray marching, not ray tracing. Ray marching takes steps through an implicit surface, in this case the depth buffer, while ray tracing does full ray/triangle intersections. Games have been doing SSR with ray marching for a decade at least [0]. Just inverting the image would only work on perfectly flat surfaces exactly aligned with the camera. [0] https://jcgt.org/published/0003/04/04/paper.pdf https://jcgt.org/published/0003/04/04/paper.pdf