lampstone

The coursed basalt the lighthouse Lucina is built out of, drawn from the fragment's world position rather than from a texture.

Courses run in Y and stones run along whichever horizontal axis the surface faces, in a running bond whose offset and stone length change course by course, so no two rows line up. Each stone takes its own value off a hash, the joint between them is recessed and occluded rather than merely darker, a blotchy weathering field breaks the whole face, and a salt bloom creeps up out of the sea over the lowest courses. course, block_length and joint are metres, so the same material serves the wall, the lintel and the floor flags at different settings.

It hands the engine a PbrSurface, so it lights, shadows and reads on the albedo / roughness / normal capture passes like any engine-lit material.