Beta Fluid-Simulated Afterfire 0.3.0-beta

Fluid-Simulated Afterfire (beta)

Exhaust flames simulated in real time.Fluid-Simulated Afterfire replaces the game's afterfire sprites with a small fluid simulation of hot gas on the GPU, so every pop and flame has its own shape, colour and motion. Its behaviour follows published research on combustion in exhaust systems, flame light and hot jets, and was tuned against footage of real cars.

This is a beta. It works on the cars and maps it was tested on, but you may find bugs. Please report them (see below).

​

What it does

• Every car with afterfire, nothing else. Flames appear when the game's own engine model makes an afterfire likely: lifting off, the rev limiter, gear shifts, anti-lag. Cars that never backfire in the stock game (diesels, for example) stay quiet.
• A real flame, not a sprite. Each flame is a small simulation: weak pops are small and bluish, strong ones yellow and orange. Flames are swept back at speed, blown by the wind and spread on the ground.
• Dual exhausts fire like dual exhausts. Outlets on separate pipes pop independently; tips on the same pipe fire together.
• Light. Flames light the road and the car at night.

Each car, its own afterfire

​

The mod does not add afterfire to a car. It takes each car's afterfire from the game's own values, so every car reacts differently, depending on its engine and exhaust. A car that does not backfire in the stock game will not backfire with the mod either. If the result feels too strong, lower Intensity in the settings.

Flames and the ground

The flame is a flow of hot gas, and the road is part of that flow: gas that reaches the ground cannot pass through it, so it spreads along the road instead. The rest of the scene is not part of the simulation yet: flames pass through the car's own body, its wheels, other cars, walls and other objects. Making them collide with these is planned for later.

​

Requirements

• The DirectX 12 renderer (the game's default). On other renderers the mod stays off and the game's own afterfire is used.

Settings

​

Press Esc, open the Mods tab, then Fluid-Simulated Afterfire.

​

• Enabled: turns the mod off; every car then uses the game's own afterfire.
• Quality: Low to Ultra. Lower settings use a coarser simulation, fewer flames at once and a shorter distance. Ultra is the reference look.
• Intensity: how strong each afterfire is: a stronger one is larger, brighter and more orange. Realistic follows each car's own afterfire.
• Size: scales every flame, from tiny to huge, keeping its shape.
• Lifetime: how long each flame burns and how far it reaches, from a brief flash to a flamethrower.
• Frequency: how often the exhaust pops and flames, sound included.
• Traffic: flames on traffic cars, or the game's own afterfire for them.
• Extra: flame and gas colours, for fun.

Realistic is the default, and the look we tuned against real cars. The sliders go well past it, in both directions:


Green. Because you can. The light turns green too, and so do your wheels


Small and brief. For quiet neighbourhoods.


Huge and long. The neighbours are already on the phone.

Planned for later

• Simulated exhaust smoke: a real gas flow on the GPU, like the flames, coming out of the tailpipe.
• Flames that stop against walls, wheels and other cars (for now they pass through).

To investigate

• Shade and fog: flames are not darkened by shadows or dimmed by fog,
• Multiplayer (not tested yet).

Reporting a bug

In the menu, press Report a bug: the report is copied and saved to a file. Paste it in the bug-reports channel of the Discord and attach the file. The mod never sends anything over the internet.

If the game stops while the first flames of a session appear, the mod starts off next time and its menu offers to try again.

Discord

News, ideas and help: join the Discord.