Spread, wind and weather

Fires spread downwind over time based on the wind, the weather and the fire type's fuel. Spread is server-authoritative, so every player sees the same growth.

The difficulty dial

Config.FireSpread.BaseChance is the single setting that decides how hard your fires are.

A spread child lives ChildTimeout seconds — so ChildTimeout / Interval rolls — and may have at most MaxChildren of its own. The children each fire actually leaves behind works out roughly as:

min(MaxChildren, (ChildTimeout / Interval) * BaseChance * fuel.rate * wind)

Above 1.0 the fire grows; below 1.0 it burns itself out.

At the shipped values a normal fire in average wind sits near 1.8 — it grows steadily and will beat one firefighter, but a crew that keeps working it wins.

Raising BaseChance to 0.25 puts every fire type above 3.0, which is a wall of flame no crew can outpace.

Fires advance as a front

EdgeOnly means only fires on the edge of the burn throw children. Without it every fire in the scene breeds, including the ones deep inside, and the fire reads as one solid carpet.

Real fire advances as a front with a spent core behind it — which is also what makes a fire flankable: cut the front and the middle burns itself out.

Merging and drift

• A child that would land on top of an existing fire merges instead
• MaxDrift is a hard leash on how far a fire may spread from where it originally started, so a chain of children cannot walk across the map

Validation

Before a child is placed, the nearest player's client checks the spot: solid ground under it, no more than MaxHeightStep off the parent's height, not in water, a clear line from the parent, and not under a roof with no interior behind it.

With RequireValidation = true, nobody close enough to check means the child is simply not spawned and the parent tries again. Setting it false restores the old behaviour where an unchecked child went ahead at the parent's height — which is exactly the fire floating in mid-air, or burning inside a wall, that a crew finds when they arrive.

Wind and weather

• WindInfluence — how tightly the wind aims the spread. 0 = any direction, 1 = a narrow cone straight downwind. Direction only
• WindRateMin / WindRateMax — what the wind does to the spread rate, across the whole 0..1 strength range. A calm day drops a normal fire below 1.0 so it burns out on its own; a gale roughly doubles it
• WeatherWetPenalty — rain and snow multiply the spread chance by (1 - this)

Set wind manually with /setwind, or feed live values from your weather resource. AutoDetect reads the game's actual weather and sets wet/dry from it — turn it off if a weather resource is pushing values in.

Reignition

An extinguished fire can flare back up shortly after. Reignite.Chance, Delay, Flames, Spread, Timeout, and RequireDryWindy to only do it in dry, windy conditions.