Exercise: a modular room

A modular room is one interior space assembled from a small kit of reusable pieces that snap together on a grid. This brief asks you to design the kit, build it, break it on purpose, and dress and light one room from it.

The exercise shows how studios build levels, because the kit has to work for people other than its author. The Level Design Book's warning applies: "Your first kit will probably be very hard to use" (The Level Design Book: Modular kit design). Working out why is part of the exercise.

#The brief

Goal. Build a 12 × 8 m room, 4 m floor to ceiling, from no more than ten unique kit pieces, then dress and light it so it reads as a specific place: a pump room, an archive, a chapel, a ship's mess.

Scope. One room, one doorway, one window wall, and enough kit to build a second, different room without new meshes. Props are limited to what tells the room's story (see set dressing and art passes).

#Constraints

#Stages

#1. Metrics on paper

Decide the player's size and the spaces it needs: door width and height, ceiling height, step height. Draw the room on squared paper at one square per 2 m. See grids and metrics, player collision capsule and scale and proportion. Write the metrics in a short art bibles and style guides note so the kit and the level agree.

#2. Blockout

Build the room from grey boxes in the engine and walk it with the default character before modeling anything. See blockout and gym levels and metrics maps. Change the plan now if the doorway feels cramped or the room feels empty; it costs minutes here and days later.

#3. Building the kit

Model the pieces from the list: straight wall, corner, doorway wall, window wall, floor, ceiling, one variant of the straight wall, a skirting or cornice trim, and glue pieces such as a pillar to hide joins. The Level Design Book calls glue "essential for tunnel or cave kits" (The Level Design Book: Modular kit design); even in a square room, a pillar or pipe over a seam saves you from perfect joins. Give each piece clean lightmap UVs if your engine bakes light, and simple collision.

Texture the kit with trim sheets and tileable materials rather than unique unwraps. Plan variety in the surfaces, not the meshes: "Texture variations go a long way" (The Level Design Book: Modular kit design). See vertex painting and blending, decals and detail maps and macro variation.

#4. Stress testing

The Level Design Book is blunt: stress-test the kit, and "do NOT just stop at an ideal case" (The Level Design Book: Modular kit design). Build three test layouts in a separate map before you build the real room:

1. Stack test. Two storeys on top of each other.
2. Loop test. A ring of walls and corners that must return exactly to its starting pivot.
3. Gap test. Light the test map brightly from outside and look for any seam where light leaks in.

Then make a showcase map: "a scene or level with every prop / art asset, and walk around in it" (The Level Design Book: Environment Art). See showcase (warehouse) map.

#5. Assembly, dressing and lighting

Build the final room from the kit. Then reduce the visible repetition. Burgess warns that unique detail on a repeating piece becomes the thing players notice, and that kit-built levels can "show the grid" (Game Developer: Skyrim's Modular Approach to Level Design; 80 Level: Building Huge Open Worlds: Modularity, Kits &…). On The Witcher 3, Michał Janiszewski describes the opposite habit for set dressing: "By not using a grid for mesh placement and having everything slightly imperfect we make it more believable" (80 Level: World Building of Witcher 3). Snap the architecture; place the props by eye. See art fatigue, set dressing and art passes and environmental storytelling.

Light it with one clear key light, usually the window, and only the practical lights the story justifies. exercise: lighting one scene four ways covers this in depth.

#6. Presentation

1. Two or three beauty shots of the lit, dressed room.
2. A kit sheet: every piece laid out on the grid, labelled, with its triangle count. Adrien Thierry's Dishonored post shows "All exterior modules" next to the one "Texture sheet" that covers them (ArtStation: The Golden Cat).
3. A wireframe of the assembled room.
4. The trim sheet and tileables, with the texel density written on them.
5. A before-and-after: the grey-box blockout next to the final shot.
6. The second room built from the same kit, as proof the kit is reusable.

See making (and reading) an art breakdown and planning a portfolio piece.

#Shipped kits to study

Before you plan your kit, look at how shipped kits are presented. For each, count the unique pieces you can see and note how the artist shows that they snap.

• One kit, a whole map. Paweł Kostecki's tomb kit for Indiana Jones and the Great Circle "was used to assemble all of the tombs" on the Gizeh map; other artists later "expanded it and created custom pieces using finalised trims and tilables" (ArtStation: Indiana Jones and the Great Circle - Tomb Kit).
• Modules plus one texture sheet. Adrien Thierry's Golden Cat bath house for Dishonored lays out its exterior modules beside the texture sheet they share (ArtStation: The Golden Cat).
• A set that travels. Tim Wilmsen's glasshouse set for Baldur's Gate 3 was planned for the Iron Throne, and pieces were later made for The Foundry, Lower City buildings and Ramazith Tower (ArtStation: Baldur's Gate 3 - Glasshouse Modular Set).
• Instances inside buildings. Edgar A. Martinez's The Last of Us Part I wireframes of Bill's Town note that "All building share many instances" (ArtStation: "The Last of Us: Part I"…).

#Further reading and watching

• modular kits, grids and metrics and glue pieces: the theory behind this brief.