sigma_surface

A metallic-roughness surface whose detail is generated from world-space position instead of sampled from textures. detail_kind selects one of seven height fields — smooth, floor tile, cinderblock, brushed metal, woven matting, plank, painted gloss — and that single height field drives albedo darkening in the recesses, roughness variation, ambient occlusion, and a bump normal taken from the field's world-space gradient. detail_scale sets the size of the pattern in world units, so a unit cube scaled to a 40-metre floor and a 1-metre prop both come out with correctly-sized features.

base_color is the surface hue and accent_color tints the recesses (grout, mortar, plank seams). wear controls how much the proud edges polish and lighten; grime controls large-scale blotching that keeps flat expanses from reading as a single flat value. sheen sharpens reflections at grazing angles for polished floors. Lighting comes from zero::pbr.