lamp_fog

The volumetric fog of Lamplighter's Round, as a post-process pass. It marches the camera ray through the air between the eye and the depth buffer's surface, gathering in-scattered light at each step from a cold moon lobe, a flat ambient floor and up to nine gas lamps supplied as (x, y, z, power) uniforms, and dims the surface behind by the transmittance it accumulated. A burning lamp therefore lights the AIR around it — a visible cone through the fog — and also thins the fog on its own stretch of street, which is what opens a pocket of visibility when a lamp takes. power is 0 for a lamp still dark.