mat_moss

# fl_surface The forest-floor surface shader of *First Light: Goura*. The ground, the bark, the buttress roots, the fallen logs, the leaf litter and the roost tree all draw through this one shader; what makes them different things is the material. It is a `surface()` shader — it fills a `PbrSurface` and the engine lights it — built for a place that is seen first in near-darkness and then in low, raking gold light. Two properties of that place are what the shader spends its budget on: variation that does not repeat across a 120 metre lane, and a normal broken up finely enough that a low sun rakes it. ## What it does Three world-space noise fields stack, each with its own scale so they pool in different places: | Field | Reads as | |---|---| | macro | which of `base_color` / `alt_color` this patch of surface is | | damp | wet duff, mud, the dark under a log — darker and much glossier | | moss | growth on upward-facing geometry only, gated by `moss_facing` | A fourth, finer field speckles the albedo, roughens it unevenly, and — through its gradient — perturbs the shading normal, which is what gives bark its grain and litter its tooth without a texture. `emissive` + `emissive_intensity` is how the roost crown catches the first gold: the `Floor` component raises the intensity as `dawn.light()` rises. ## Vertex colours Per-vertex colour is half the authoring surface: - `rgb` multiplies the albedo. Every mesh the floor slice builds paints its own large-scale variation into it — a trunk darker at the base, a log bleached along its top, the ground pooled into shadow around cover. - `a` drives ambient occlusion between `cavity` and 1, so a mesh can bury its own crevices without a baked map. ## Properties `properties.yaml` carries the full set with defaults. The ones that decide the look: `base_color` / `alt_color`, `grain` (scales every field at once), `macro_scale`, `detail_scale`, `bump`, `damp_amount`, `moss_amount`. Set `double_sided` on a material whose geometry is drawn with `cull: none`.