Generate scene bg

Generate Scene BG

Generate scene background illustrations for ADV / Visual Novel style games (Persona, Ace Attorney, etc.). Output is a finished single-image backdrop, not a layered game map.

Parameters

Infer from the user request. Only prompt is required.

• art_style: anime_illustration | semi_realistic | painted_scene | cel_shaded | project-native
• prompt: the user's scene description
• aspect_ratio: 16:9 (default) | 4:3 | custom WxH
• time_variant: optional — day | sunset | night | rain | overcast | custom

When unspecified:

• Default art_style to anime_illustration.
• Default aspect_ratio to 16:9 (1920x1080).
• Omit time_variant unless the user asks for a specific time or weather.

Workflow

Step 1 — Scene Plan

From the user's description, infer:

• What location this is (classroom, courtroom, café, rooftop, etc.)
• Art style and aspect ratio
• Whether a time variant is requested
• Output file naming: assets/bg/<scene-name>.png

State the plan briefly and confirm before generating.

Step 2 — Generate Background

1. Write the image prompt manually. The prompt must describe:
   • The scene composition, perspective, and depth
   • Art style cues matching the chosen art_style
   • Lighting and atmosphere matching time_variant if set
   • "No characters, no text, no UI elements" — backgrounds must be empty of actors
2. Call image_gen with the prompt. If the agent has no native image_gen tool (e.g. Claude Code), invoke it via Bash instead: scripts/call-codex-imagegen.sh -o assets/bg/<scene-name>.png "<prompt>" — this bridges to Codex CLI's image_gen.
3. Save the prompt as assets/bg/<scene-name>.prompt.txt.
4. Validate: correct dimensions/aspect ratio, no baked-in characters or text.

Generating Variants (same scene, different time/angle)

When the user asks for a variant of an existing background (e.g., "same classroom but at night"):

1. Make the original background visible in conversation context. If it is a local file, call view_image immediately before writing the variant prompt.
2. In the variant prompt, explicitly say: use the visible image above as the visual reference — preserve the room layout, furniture positions, perspective, and composition. Change only the lighting/atmosphere/weather to match the new variant.
3. Generate the variant and save as assets/bg/<scene-name>-<variant>.png with its own .prompt.txt.
4. Save the base prompt alongside the variant prompt so the lineage is traceable.

This is best-effort consistency — image generation does not guarantee identical composition across variants. The visual reference handoff improves consistency but does not make it pixel-perfect.

Prompt Guidelines

Art Style Cues

Style	Prompt cues
anime_illustration	anime-style background illustration, detailed anime scenery, soft lighting, clean lines
semi_realistic	semi-realistic digital painting, detailed environment art, cinematic lighting
painted_scene	hand-painted background, watercolor-inspired, painterly atmosphere
cel_shaded	cel-shaded background, flat color with clean outlines, stylized shading

What to Include

• Perspective and camera angle (eye-level, slightly elevated, wide shot, etc.)
• Key architectural/environmental features
• Lighting direction and quality
• Atmosphere and mood through visual description (not a separate mood parameter — describe it in the prompt)
• Time of day through lighting and sky cues when time_variant is set

What to Exclude

• Characters, people, silhouettes, or figures
• Text, signs with readable text, UI elements
• Game HUD or overlay elements

File Structure

assets/bg/
  classroom.png
  classroom.prompt.txt
  classroom-night.png
  classroom-night.prompt.txt
  courtroom.png
  courtroom.prompt.txt

Validation

• Output image matches requested aspect_ratio
• No characters or text baked into the background
• Prompt file saved alongside every generated image
• Variant filenames follow <scene-name>-<variant>.png convention

Boundaries

• Character sprites, standing illustrations → generate-tachie
• This skill produces scene illustrations only — no runtime metadata, no engine wiring