Adds a hardcoded sun direction + ambient + Lambert diffuse to both
terrain.frag and mesh.frag. Both vertex shaders now forward a world-
space normal (computed as mat3(uModel) * aNormal) for the fragment
shader to dot against the sun vector.
Lighting model:
final_rgb = texture_rgb * (AMBIENT + DIFFUSE * max(0, dot(N, SUN)))
where AMBIENT=0.4, DIFFUSE=0.6, SUN=normalize(0.4,0.3,0.8).
Building walls facing the sun light up, walls in shadow dim to ~40%.
Scenery (trees, bushes, rocks) with real per-vertex normals from SWVertex
shades naturally. Terrain currently uses flat UnitZ normals so every
terrain fragment gets the same contribution — terrain will look a bit
washed out compared to real AC until a Phase 3b pass computes per-vertex
landblock normals from the heightmap.
Non-uniform scale (from scenery's random scale baked into MeshRef
PartTransform) would technically require the inverse-transpose for
correct normals, but scenery uses uniform scale so mat3(uModel) is
good enough. Flagging as a known Phase 3+ concern if nonuniform scale
ever shows up.
Build clean, runtime clean: 1133 entities hydrated, no shader compile
errors, process runs through startup.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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