Volumetric Explosions

A Kerbal Space Program 1 mod that replaces the game's flat explosion sprites with a small simulation of fire, smoke and dust, drawn as a true volume.

Thousands of particles are carried by a model of the air, gathered into a 3D grid of smoke and heat, lit by the sun, the sky and the fire, and drawn by a shader that walks a ray through that grid for every pixel: the way Counter-Strike 2 draws its smoke grenades. There are no pictures of explosions in this mod. It needs no other mod and changes nothing but the look.

Left: the game's own explosion. Right: the same blast with the mod.

Install

Copy the VolumetricExplosions folder from the download into your KSP GameData folder and start the game. To remove it, delete that folder. For KSP 1.12.x; it needs no other mod.

On a Mac, a copy downloaded with a browser runs slower until you allow its library with one command: see Installing.

What you get

• What blew up decides the look. Fuel and oxidiser give an orange fireball and thick dark smoke; solid propellant a white-hot flash and pale smoke; monopropellant a pale yellow fire; a battery a blue-white flash; xenon a cold white burst; ore, dust. The size comes from how much there was.
• So do why and where. A crash throws fire and dust on ahead; thin air lets a blast spread wide; in a vacuum there is no smoke; without oxygen, fuel alone does not burn; at night smoke is lit by its own fire.
• Smoke that behaves like smoke. It rises and rolls into a mushroom, drifts on a wind (when there is one), lies on the ground as the ground really is and runs downhill when it has cooled, goes round buildings and ships, and is pushed about by craft and their exhaust.
• Shock fronts that bend the picture as they pass, pieces of the destroyed parts, and burn marks thrown onto whatever surface is there.
• Shadows and lamps (0.5.0). Smoke throws its shadow on the ground, buildings and ships under it in sunlight, and at night is lit by the lamps round about as well as by its own fire.
• Wakes and depth (0.5.0). What flies through smoke leaves a ragged tunnel that churns and fills in behind it, a plane's wing tips roll the smoke up and its downwash carries it down; smoke in front always hides smoke behind, whichever patch of air each is in; a fireball turns to smoke from the outside in, and burning wreckage sends up plumes.
• Its air takes more than explosions (since 0.4.0). Another mod can feed it the smoke and the flames of rocket engines: see engines' smoke and flames. By itself the mod does nothing with engines.

Each panel is a blast of its own. The battery and the xenon tank are seen from closer: they are small.

Settings

In GameData/VolumetricExplosions/PluginData/settings.cfg. The ones most worth knowing: quality (0.2 light to 3 heavy), size, smoke (how long it hangs), wind, and enabled = false to have the stock explosions back. All of them.

Where it works

• Mac: made and tested here (KSP 1.12.5, OpenGL).
• Windows: tried on Windows 11 (KSP 1.12.5 on its own Direct3D 11): the smoke is drawn as a volume there too, by the same shaders compiled for Direct3D, which are in the download. On Windows and Linux the mod does its heaviest sums with its own code; the small library that does them faster is in the download for the Mac only.
• Linux: the game runs on OpenGL there too, so it should work the same. Never run.

What it costs: on an Apple M5 Pro at 1280 x 720, a 4-tonne fuel fire filling half the view took the game from 79 frames a second to 56 in its first seconds and 70 to 75 once it was smoke.

More

• What decides how an explosion looks
• What the smoke does
• Shock fronts, debris and burn marks
• How it is drawn, and where
• What it costs and what was tested
• Limits
• Building it yourself

Source, and more

github.com/IshiakiZ/ksp-volumetric-explosions: the source, the wiki with the long description, and where to report a fault. Licence: MIT.