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:

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.