Rendering and effects

The simulation reports what happened: a shot was fired, a wall was hit, a body bled. The adapter decides what that looks and sounds like, then hands it to Unity, which draws the frame. Every flash, splash, scorch and glow goes through one chain, and none of it can change the game.

From a report to a picture

The effect law

Every effect in the engine keeps the same handful of rules:

Effects follow kinds, never names. Twelve pistols are one kind of weapon and three carpets one kind of surface, so a new weapon or enemy needs no new effect code; a new look is one recipe and one row. And light and matter are drawn differently: flames, sparks, flashes and tracers add light, while smoke, dust and blood cover what is behind them. Blood that added light would glow; smoke that did would vanish against a lit wall.

Unity itself does the drawing and the lighting. The engine decides what is in each picture, and it asks the same things of every shooter, the player and enemies alike.

The effect resolver

The resolver is the one place that decides what a circumstance looks and sounds like. An event goes in (a body was hit, a footstep landed, a rocket exploded) with its circumstances, and one finished choice comes out for each thing the caller asked about.

Inside a layer, the row that matches the circumstances most closely wins: what happened first, then the kind of round, the kind of damage, the weapon and the surface it landed on.

Where a choice has variations (three textures of scorch, a range of tints), the pick is fixed by the thing itself rather than rolled at random, so a replay looks exactly like the original. The engine registers none of these rows itself: a game that registers nothing gets the engine's stock looks everywhere.

Recipes and the light budget

The resolver names a recipe; the recipe says what the effect is made of. It is a stack of layers, each with its own timing, size and tint, and two players draw them: one for bursts that play once, one for effects that run until they are stopped.

A recipe can put marks on the level, but never a patch of blood. A blood patch is part of the game, because it hands out footprints, so only the simulation can create one (the section on blood below shows the split). A recipe's marks are the kind a hit leaves, such as a scorch or a scratch.

Every effect light is claimed from one budget: muzzle flashes, explosions, burning ground, glowing rounds, burning bodies. Once a frame the budget lights the ones nearest the camera, up to its cap, and darkens the rest. In a measured busy fight the engine wanted about twenty lights at once, and a cap of 32 lit all of them for only a small cost.

32

effect lights lit at once, nearest first

4

layers an answer can come from

Engine defaults as of 2026-10-22; a game sets its own light cap.

Shots, impacts and gore on screen

A shot's flash, its first stretch of tracer and a round's launch all leave from the muzzle of the gun in the shooter's hands, worked out on the tick of the shot. A beam or a lamp held over time follows the gun instead.

• Hits on bodies throw a spray that matches what was hit: sparks off a machine, chips off bone, blood in the victim's own colour.
• Hits on the level leave a mark chosen by the round and the surface: a bullet hole, a scorch crater, a branching burn, a slash cut or a smear. One round can mark flesh, concrete and sheet steel three different ways.
• Blood comes in three shades of each colour, so a pool, a spray and a drip never look stamped from one mould. Drops fly as small flecks, chunks tumble and land wet, and a limb torn off shows a cut end.
• Statuses are drawn on the body that has them: flames that cling and lick upward with black smoke, a sickly taint that discolours and drips, a still, spiked shell around a body that has been stopped.

Blood: who decides what

Blood is split cleanly between the two halves. The simulation decides that there is blood, where it is and whose it is. The effect resolver decides how it looks.

Where a look has variations, the patch itself fixes which one it gets, so a replay draws the same stains. Two patches the simulation placed the same way can still look quite different: a creature's own blood can wear its own texture, a broken joint can leave a different stain from a bullet wound, and a stain on tiles can differ from one on concrete. What the resolver can never do is add a patch, move one or take one away.

Marks that stay: drying and the scenery bake

A fresh stain is dark and glossy and dries to matte over half a minute. It dries in small steps rather than smoothly, which is cheaper to draw; at a glance the steps do not show.

Blood, footprints and settled gore stay for the life of a level, so their number only grows. Three things keep that affordable without deleting anything:

• The bake. Finished marks and settled chunks are folded into a few large combined shapes instead of each being drawn on its own. The eye must not see any difference when a mark is folded in.
• Hiding the buried. A mark completely covered by later blood is no longer drawn. Partly covered marks stay visible: the layered mess is part of the atmosphere.
• Sleeping views. A corpse or chunk that has fully settled, dried and stopped turning stops being updated at all.

None of these touch the simulation: a baked or hidden mark is still there in the game, still handing out footprints.

Liquids, glass and pickups

See-through things are drawn in a fixed order, so water, glass and blood never flicker as the camera moves.

Under water, the view is tinted only when the camera itself is in the liquid, so in third person a camera above the surface stays clear while the body's head is under. The tint fades in across the waterline instead of switching, which would strobe as the waves moved.

Pickups are built to be read at a glance: a weapon lies there as the same model the hands hold, ammunition is a colour-coded crate with an emblem on the lid, health a box with a cross, armour a plate with a piece for each grade, and a powerup a glowing token on a plinth. A game can replace any of these with its own models.

• GoreWhat the simulation decides about chunks, blood and corpses.
• Weapons and projectilesThe shots, rounds and blasts these effects show.
• Animation and bodies on screenThe bodies and guns the effects leave from.
• Life of a shotOne bullet through every system, start to finish.