Set dressing and art passes

Set dressing is placing props, decals, clutter and detail into a space so it reads as a real place. An art pass is one round of that work, from the first swap of grey boxes for real geometry to the last scatter of debris. The Level Design Book defines art passing as "painting / placing decor to supplement the underlying design" (The Level Design Book: Environment Art).

The definition stresses supplementing the design. The book defines environment art as "the cosmetic decoration of a level or game world, while preserving its core functionality and gameplay" (The Level Design Book: Environment Art). Set dressing that breaks the layout, hides the route or creates fake ledges counts as a bug.

#When the art pass starts

The Level Design Book says artists usually "wait for a mature blockout before beginning an art pass" (The Level Design Book: Environment Art). It mentions that on Valorant, an intermediate "art blockout" stage "gives extra time for level designers to make more changes to the level geometry" (The Level Design Book: Environment Art). Epic's greyboxing guide gives the same order: "Add props and art once you are happy with how the level plays" (Epic Developer Community documentation: Greyboxing in Unreal Editor for Fortnite).

#Working in passes

The Level Design Book's two rules for art passing are to "work iteratively in stages" and to "start big, and save smaller details for later art passes" (The Level Design Book: Environment Art). It also advises to "art pass with focus", so feedback on each pass stays coherent (The Level Design Book: Environment Art). A typical sequence:

1. Kit and materials. Replace blockout shapes with kit pieces, tileable materials and trim sheets. Check that every metric survived. See grids and metrics.
2. Primary props and heroes. Place hero assets and large props that define the room's function.
3. Secondary props in clusters. Furniture, machines, crates. The Level Design Book's advice: "try to compose the set dressing in clusters of related details" (The Level Design Book: Environment Art).
4. Detail. decals, mesh decals, small clutter, cables, vertex painting and blending for grime and moss.
5. Light and atmosphere. Often done by or with lighting artists. See real-time lighting and fog and atmosphere.
6. Polish and validation. Walk the whole level; fix collision, floating props and Z-fighting.

#Principles of good set dressing

#Readability

"Everything in environment art has a readability function", according to The Level Design Book (The Level Design Book: Environment Art). Clutter competes with that: "An art passed level that is 'busy' will be 'illegible' and difficult to read" (The Level Design Book: Environment Art). Leave quiet areas so the eye can find the route, the focal point and interactive objects. See visual hierarchy and readability.

#Affordance rules

Emilia Schatz's Uncharted rules, such as no climbable-looking edges between 3.25 m and 4 m, have to survive dressing (80 Level: Defining Environment Language for Video Games). A decorative cornice, pipe or shelf at the wrong height becomes a fake ledge. A safe habit: before placing any prop with a flat top, ask whether it sits inside a gameplay height band. See affordance and signifier.

#Prop clusters

Props scattered evenly look placed by a computer. Grouping related items (a desk with its chair, lamp and papers; a workbench with tools and scraps) makes each cluster read as one idea and leaves calm space between. For vegetation, The Level Design Book adds: "don't put canopy on every trunk and make sure there's detail at the base" (The Level Design Book: Environment Art).

Reuse works for props as well as clusters. Adrien Thierry's Dishonored 2 post on the Clockwork Mansion's maintenance areas captions its pipes as ones "you can find in many other Dishonored 2 levels" (ArtStation: Clockwork Mansion maintenance areas): a few well-made dressing pieces carried through a whole game.

Okan Beyit describes planning secondary assets "for the purpose of framing and enhancing the primary assets" (80 Level: Preparing Assets for Environment Design): the secondary dressing supports the hero assets.

#Room function and logic

Dan Cox's GDC 2014 talk "What Modern Interior Design Teaches Us About Environment Art" draws parallels between interior design and level art (GDC Vault: What Modern Interior Design Teaches Us About…). Ask what each room is for, who used it and how: where would the desk go so light falls on it, where would the bins be, which path across the room has worn the floor? Carson's theme-park rule applies: once the world's rules are set, "you do not break them!" (Game Developer: Environmental Storytelling: Creating…). See environmental storytelling and worldbuilding for artists.

#Real materials, restrained colour

The Level Design Book advises that "an environment texture should read as a distinct real world material", and to "Avoid deeply saturated colors, give space for lighting" (The Level Design Book: Environment Art). Saturated props fight the lighting artist and draw attention away from the things that matter. See colour for environments and value.

#Hiding seams with props

Off-grid joins between modules are hard to make clean. The Level Design Book's pragmatic advice: "just let the modules freely intersect, and then cover the messy intersection with another object" (The Level Design Book: Environment Art). Pillars, pipes, rubble, foliage and cables are classic seam-hiders. See kitbashing.

#Validating the dressing

• Showcase map. The Level Design Book recommends making "a scene or level with every prop / art asset, and walk around in it", sometimes called a warehouse map (The Level Design Book: Environment Art). It catches scale, material and collision errors before assets are spread across levels.
• Collision walk. Walk every route with the player capsule after dressing; props are the most common source of snagging. See collision meshes.
• Readability test. Re-run the blockout playtest with fresh players and compare. If they found the route before and don't now, the dressing is the likely cause. See playtesting spaces.
• Performance check. Dense dressing costs draw calls and memory. Use instancing, shared materials and LODs. See performance and profiling.

#Further reading and watching