Three.js Image Generator

Purpose

Create game-useful 2D assets and references for Three.js projects. This skill is the image-generation layer for the Three.js game system: it produces concepts, textures, decals, UI art, and 2D inputs that can be handed to threejs-3d-generator for image-to-3D model creation.

Provider: Google's Gemini image API.

Resolve <this-skill-dir> in the commands below in this order: ~/.claude/skills/threejs-image-generator, ~/.codex/skills/threejs-image-generator, ~/.agents/skills/threejs-image-generator, or repo skills/threejs-image-generator.

When To Use

Use this skill before procedural-only fallback when a Three.js game needs:

• 2D-to-3D reference images for threejs-3d-generator: characters, creatures, buildings, ships, cars, weapons, props, pickups, terrain modules.
• Texture and material references: terrain, road, rock, sand, metal, sci-fi panels, trim sheets, decals, hazard labels, signs.
• Environment images: skies, backdrops, city horizons, nebula plates, menu backgrounds, parallax layers.
• UI art: logos, faction marks, icons, item cards, ability badges, cockpit decals, GUI panels, title art.
• Existing-image edits, style variants, cleanup, palette alignment, or concept sheet refinements.

For premium/AAA/showcase graphics work, generate at least one relevant image for high-value 2D surfaces or image-to-3D inputs unless the credential probe or a real generation attempt shows a blocker.

API Key

Never store API keys in skill files or browser/game code, and never paste a key value into a report. The script reads --api-key or GEMINI_API_KEY.

Step 0, before declaring the key unavailable: run this skill's own probe and paste its literal output into the report.

uv run <this-skill-dir>/scripts/generate_image.py probe   # prints GEMINI_API_KEY=SET|MISSING

GEMINI_API_KEY=MISSING is only a valid skip/blocker reason when this output is shown. Keys defined only in a shell profile can be absent from the process env; if the plain probe prints MISSING unexpectedly, wrap it: zsh -lc 'source ~/.zprofile 2>/dev/null || true; source ~/.zshrc 2>/dev/null || true; uv run <this-skill-dir>/scripts/generate_image.py probe'. When the director skill is loaded, prefer threejs-game-director/scripts/probe_asset_credentials.sh, which probes all three asset keys at once.

Tool Script

Run from the user's current project directory so output lands in the game project:

uv run <this-skill-dir>/scripts/generate_image.py --prompt "your image description" --filename assets/concepts/output.png --resolution 2K

Edit an existing image:

uv run <this-skill-dir>/scripts/generate_image.py \
  --input-image assets/concepts/ship.png \
  --prompt "turn this into a battle-worn red racing livery with clearer material zones" \
  --filename assets/concepts/ship-red-livery.png \
  --resolution 2K

Resolution mapping:

• 1K: quick concepts, icons, draft sheets.
• 2K: default production reference for image-to-3D, textures, backgrounds, UI panels. This is also the script default when --resolution is omitted.
• 4K: hero splash/title art, high-detail texture references, large sky/background plates.

Prompt Patterns

Image-to-3D reference:

Create a clean 3D-generation reference image of [asset]. Centered single object, full object visible, plain light background, readable silhouette, clear material zones, game-ready [genre/style], no motion blur, no cropped parts, no text.

Riggable character/creature reference:

Create a full-body [T-pose/A-pose/side-view creature] reference for 3D rigging: [details]. Symmetric stance, visible hands/feet/limbs, plain background, readable costume/anatomy layers, no weapon fused to hands.

Texture/material reference:

Create a seamless game texture reference for [surface]. Orthographic/top-down, PBR-friendly albedo, clear material variation, no perspective, no baked strong shadows, [style/material details].

Logo/icon/UI art:

Create a crisp game UI [logo/icon/badge/panel] for [faction/item/ability]. Transparent-friendly silhouette, high contrast at small size, [genre styling], no tiny unreadable text.

Sky/background:

Create a wide game background plate of [environment]. Layered depth, readable horizon, [time/weather/style], suitable behind a real-time Three.js scene, no foreground subject.

Three.js Integration Rules

• Save concepts and image-to-3D sources under assets/concepts/.
• Save textures, decals, icons, and GUI source images under assets/textures/, assets/decals/, or assets/ui/.
• For image-to-3D, hand the saved image path to threejs-3d-generator and record the chain in the external asset ledger.
• Do not call the image API from client-side game code.
• Convert generated PNGs into runtime formats deliberately: PNG for alpha/UI, JPG/WebP/KTX2 for larger opaque textures where the project pipeline supports it.
• Verify how the image appears in game, not only that the file exists.

Required Report

Report:

• Credential probe output or command blocker.
• Prompt and purpose.
• Output path.
• Resolution.
• Whether the image was used directly, edited further, or handed to threejs-3d-generator.
• Any remaining integration work such as compression, UV assignment, alpha cleanup, or atlas packing.

Do not mark a premium graphics phase complete if the needed image outputs are missing and the only justification is "procedural is enough" for high-value UI, texture, sky, decal, logo, or image-to-3D surfaces.