Light in the Dark

The nights in this world are genuinely dark, which is a deliberate choice — it makes the lights matter. A dark world with no warm light is bleak; a dark world with lamp posts, lit windows and fireflies is cosy. This post is about placing those lights.

How “night” is measured

Everything here keys off one number: how night-like it currently is, derived from the sun’s elevation. When the sun is high it’s 0; as the sun drops past the horizon it eases up to 1. The lamp glow, the firefly spawning, and the glowing windows from the houses post all scale off this same value, so the world lights up together as the sun goes down.

static func night_factor(cfg) -> float:
    return 1.0 - smoothstep(8.0, 25.0, cfg.sun_angle)

There’s also an “always on” override for worlds where you want the lights lit regardless of time.

Lamp posts along the roads

The roads from the earlier post left behind their centre-lines. The lamp system walks along each road and places posts at even spacing, set just off to the side — and it alternates which side, so the lamps zig-zag down the road like real street lighting rather than lining up on one edge.

Each lamp is a thin pole with a glowing head and an actual light. The head’s emission and the light’s brightness both scale with the night value, so the lamps are dark by day and burn warm at night. The colour is a warm amber with a little variation per lamp, so they’re not all identical.

# even spacing along the road, alternating sides
for spot in resample(road, lamp_spacing):
    var side_offset := perpendicular * side
    spawn_lamp(spot.pos + side_offset)
    side = -side

Cost control: shadows on a budget

Lights are cheap until they cast shadows, and shadow-casting lights get expensive fast. So shadows are optional and capped: only a limited number of lights are allowed to cast them, handed out on a first-come basis. The rest still light the scene, they just don’t cast shadows. It’s the kind of unglamorous limit that keeps a night scene full of lamps from tanking the frame rate.

Fireflies

In the lush biomes — Meadow and Forest — clusters of fireflies appear at night. Each cluster is a patch of small glowing motes that drift slowly, plus a soft green-tinted light so the swarm actually illuminates the grass beneath it. They’re placed by sampling the map for lush, dry spots, so you come across them in exactly the places that already feel alive.

The motes use additive blending — their light adds onto whatever is behind them — which is what gives them that glowing, floating-spark quality against the dark.

Together with the glowing house windows and the campfires, the lamps and fireflies turn nightfall from something that hides the world into something that’s worth waiting for. Which is the right note to end the technical posts on, because the next one is about the rule behind all of these choices.