Themes

Where a theme comes from

Switch the header toggle to DESIGN. The first tab of the rail reads Theme, and it opens on a screen headed Theme with the question “How should this city be dressed?” under it, and three buttons.

There is a fourth way in, and it lives inside the second: when you generate, the cloud may first offer themes it already has that match your prompt, and you can take one of those instead of generating.

Once you leave the choice screen, ← Back at the top left of the composer returns to it — while nothing is in the thread and no job is running.

Start with the default theme

The fastest way to see a dressed city. The addon ships a small project of its own, and this button takes its theme.

1. With a project open and a city in Draft, switch the header toggle to DESIGN.
2. On the Theme tab press Start with default theme.
3. The addon copies four things out of its bundled default project into your project folder — outputs.csv, outputs.usd, assets.json and the send/ folder — and then runs the same Dress City from Outputs step a finished cloud job runs.
4. The dressed city appears and the draft underneath is hidden.

Nothing is submitted to the cloud, so this spends no credits and takes as long as the import does. You can change any material, prop or detail afterwards, and you can generate a theme over the top of it later.

Two failures are worth recognising. If no project is open the report reads “Could not append: no active project to append into” — create or open a project first. If the build you installed does not carry the bundled project, it reads “This build carries no default project”.

The copy moves files, not assets. The theme's assets.json names the materials and props it wants by their cloud ids; the linker resolves those against what is already in your Library Folder, and says in the log when it had to fall back to something else.

Generate a theme

Press Generate theme and the choice screen becomes the composer: a prompt box, a row of small buttons under it, and the thread where the job reports itself.

1. Optionally press + to open Generation Mode and set what to generate and where the assets come from.
2. Describe the theme. Enter sends, Shift+Enter starts a new line.
3. Optionally attach up to 10 reference images, or use the camera button to take a viewport screenshot straight into the tray.
4. Press send. The thread takes over from there.

A full theme costs roughly 220–275 credits and takes about 20 minutes. The only estimate the interface prints is in the Generate with AI popup's footer — “Est. cost: ~219 credits · ~18 min” — and it is a hard-coded figure from ten completed jobs rather than a live quote. It runs low: later runs have come back at 272–274. Budget against the higher number. Costs are set out on Credits & plans.

What happens after you press send — the guides, the seeds, Approve and Regenerate — is a page of its own: Generating a theme.

Use a theme you already have

Two paths reuse a theme rather than making one. Neither generates an asset.

Use this theme. After you send a prompt, the cloud may find themes it already holds that match it. A popup headed CHOOSE A THEME opens with them; the arrows page through the matches. Use this theme adopts the one on screen — no generation. Load more fetches further matches, and once there are none left the same button becomes Generate new, which skips the library and generates from your prompt. Adopting still finishes the job: the theme's assets download and the city is dressed.

Append from a project. This takes the theme of another project on this machine. The popup APPEND FROM A PROJECT lists only local projects that actually have a theme; press Append on a row and its files are copied in and linked.

The copy is a copy, never a link. The project you appended from can be renamed, re-themed or deleted afterwards and this project keeps working.

Where the assets come from

A generated theme can build every asset from scratch, pick them out of your library, or do both. The setting is on the composer's + button, which opens a small popup titled Generation Mode with three sections: Generation (Generate materials, Generate props), Assets, and Editing mode.

Which to pick:

• —Mixed for almost everything. It is the default, and it keeps a theme from re-making a brick wall you already own.
• —Select only when you want a dressed city without paying for generation, or when your library already holds the look you are after. Nothing is generated, so nothing is generated for you to pay for — but the job still runs and is still metered, so this is cheap rather than free.
• —Generate only when the look has to be new all the way through and a near-match from the library would spoil it. It is the slowest and the most expensive of the three.

What dressed means

A theme is a set of materials, props and elements — assets.json records which ones were picked — together with the outputs that place them on your city: outputs.csv and outputs.usd. Dressing is the import step that reads those outputs and builds the result in your scene, in a collection named iCity2 Front End.

It arrives as new objects. The draft city underneath is not written over — the two occupy the same space, so the module toggle swaps them: Draft shows the draft and hides the dress, Design shows the dress and hides the draft. What that leaves in your .blend is set out in What is in your .blend after a dress.

Change the draft after a dress and the city has to be dressed again with the same theme — see Re-dressing after a change. Changing the theme itself is a new theme, by any of the three routes above.