hull_steel

Hard-surface hull steel with no textures and no UVs. Welded panel courses, rivet lines, plate-thickness variation, rolled grain, grime and oxide bloom are all generated triplanarly in world space, so one material covers a truss rib at 3x scale, a pressure hull at 5x and a cut plate at 1x with the same texel density and no seams between them.

The look starts from a height field (hs_height): panel bevel + rivets + grain. The shading normal is that field's gradient, the seam mask darkens the albedo and dulls the roughness, and the oxide/grime fields pull metallic down where the surface has stopped being metal. Because the seams are real geometry-shaped normals rather than a painted grid, they shade correctly from any light direction — which is the whole point under one hard sun.

Exposes surface(), so capture { pass = "albedo" | "roughness" | "metallic" | "ao" } reads the real channel rather than the shaded pixel.

Tunables: base_color / shade_color (the two ends of the macro tone), metallic, roughness_low / roughness_high, panel_scale / seam_width / seam_darkness / rivet_amount / bump_strength, grime_color / grime_amount, rust_color / rust_amount, stripe_color / stripe_amount / stripe_scale / stripe_axis for hazard striping, emissive_color / emissive_power, and triplanar_sharpness.