<h1 align="center">sprite-gen</h1>
<p align="center"><b>One drawing in. Game-ready sprites out — as an atlas, or as transparent motion loops.</b></p>
<p align="center">
**English** · [한국어](README.ko.md) · [日本語](README.ja.md) · [简体中文](README.zh-Hans.md) · [Español](README.es.md) · [Français](README.fr.md)
</p>
<p align="center"><sub>Help cover the model API costs of developing sprite-gen with an optional <a href="https://github.com/sponsors/aldegad">GitHub sponsorship</a>. Choose your amount and a one-time or monthly contribution.</sub></p>
<p align="center"><sub>Please wishlist <a href="https://store.steampowered.com/app/5045950/">Dungeon Sookuma on Steam</a>, a game in development by the creator of sprite-gen with part of the game art made using this tool.</sub></p>
<p align="center">
<a href="https://youtu.be/zVu9YlbPtog"><img src="docs/assets/hero-v2-party.gif" width="960" alt="Animated sprite-gen v2 showcase: paladin, wolf and slime" /></a>
</p>
<p align="center"><sub>Each character started as <b>one still image</b>. Grok Imagine brought it to life; sprite-gen extracted the transparent loops, and HyperFrames assembled this showcase.</sub></p>
<p align="center">
<img src="docs/assets/village-scene.gif" width="600" alt="A samurai and companions walking through a painted village with layered scenery and projected shadows" />
</p>
<p align="center"><sub>A separate village composition made from sprite-gen assets. This GIF preserves the 10-second video at 20 fps with a 256-colour palette.</sub></p>
---
Ask an image model for a "sprite sheet" and you know what you get: a character whose face changes every frame, a background that won't key out, poses that overlap and drift off-grid, and a PNG your game engine can't actually consume. Cute demo, useless asset.
`sprite-gen` is a Codex/Claude skill and a Python CLI that closes that gap. Give it **one base image** — it drives generation row by row, locks the character's identity, strips the chroma background to real alpha, extracts each pose as a clean transparent frame, and bakes a runtime atlas **with a machine-readable `manifest.json.frame_layout`**. Or hand the same still to a video model and get back a seamless, transparent loop per motion state. For the last 10% that generation never gets right, a **curation webview** lets you compare, reject, nudge and watch the loop live before you bake.
For side sprites, `video-set` uses `--facing right|left` consistently across canvas placement and clip prompts. Its direction detector is **record-only by default** (`--facing-fix none`) and can be wrong even at high confidence. Use `gen --ref image.png --facing right` to request orientation in the generation prompt; `gen` otherwise preserves orientation. Prompts request direction but cannot guarantee the result. Correction is opt-in: `--facing-fix mirror`, or `gen --facing-fix regen`; review the still before using either. See [facing options](SKILL.md#side-view-facing).
<p align="center">
<img src="docs/assets/attack-claudecy-samurai.gif" height="160" alt="Samurai Claudecy two-handed katana cut loop">
<img src="docs/assets/attack-claudecy-samurai-onehand.gif" height="160" alt="Samurai Claudecy one-handed katana cut loop">
<img src="docs/assets/attack-slime.gif" height="160" alt="Slime attack loop">
<img src="docs/assets/attack-fox-hood.gif" height="160" alt="Hooded fox attack loop">
<img src="docs/assets/attack-paladin.gif" height="160" alt="Paladin attack loop">
</p>
<p align="center"><sub>v2.5.3 attack loops straight out of the video pipeline: one still each, Grok Imagine clip, frames gate, automatic loop selection. No manual cut points.</sub></p>
## Start with a request
Ask for **sprites** or **an image**. The agent checks access, asks only for missing provider/motion choices, runs the existing pipeline, and delivers the files. The curation view is optional. Save your choices once to reuse separate sprite and image defaults; a one-off request does not overwrite them. [User workflow and defaults](docs/user-workflow.md).
## Pipelines, independent tools and scenes
The two sprite pipelines are ordered generation flows. Tool groups contain independent commands; scene creation is an optional workflow that consumes finished assets. `sprite-gen --help` prints this map and groups commands by the code domain that owns them.
```mermaid
flowchart LR
subgraph A["A · atlas rows"]
direction LR
a1[prepare] --> a2["gen · gen-set"] --> a3[extract] --> a5[compose-atlas]
a5 -.-> a4["curation (optional)"]
a4 --> a5
end
subgraph B["B · video → loop"]
direction LR
b1[video-canvas] --> b2[video] --> b3[video-frames] --> b4[video-loop]
end
subgraph C["C · utilities"]
direction LR
c1[cutout] ~~~ c2[slice-sheet] ~~~ c3[unpack-atlas]
end
subgraph D["D · post-processing"]
direction LR
d1[recolor] ~~~ d2[export-*]
end
subgraph E["E · asset tools (independent)"]
e1[background-tile] ~~~ e2[shadow] ~~~ e3[inspect-motion]
end
subgraph S["S · scene (optional)"]
s1["existing assets + scene.json"] --> s2[scene-render]
s1 --> s3[scene-inspect]
end
```
| Pipeline / tool group / workflow | What goes in → what comes out | Docs |
|---|---|---|
| **A · atlas rows** | one still + a list of states → `sprite-sheet-alpha.png` + `manifest.json.frame_layout`, with **Breathe** baked on idle poses | [run-contract](docs/run-contract.md) · [breathing](docs/breathing.md) |
| **B · video → loop** | one still → per state, a seamless transparent GIF / WebP / strip, animated by Grok Imagine and cut at its true period | [video-pipeline](docs/video-pipeline.md) · [video](docs/video.md) |
| **C · utilities** | an imported image or grid sheet → clean transparent cuts; a finished atlas → a curator-ready run | [sheet-slicing](docs/sheet-slicing.md) · [curation](docs/curation.md) |
| **D · post-processing** | a finished sheet → deterministic colourways, Aseprite / Phaser / Flame exports | [recolor](docs/recolor.md) · [engine-export](docs/engine-export.md) |
| **E · asset tools** | independent PNGs or animations → repeating tiles, projected shadows, motion/contact measurements | [asset-tools](docs/asset-tools.md) |
| **S · scene** | existing assets + placement, camera and lighting → PNG frames, MP4/GIF, inspection and placement metadata | [scene](docs/scene.md) |
Full index: [`docs/README.md`](docs/README.md). Architecture with domain and pipeline diagrams: [`docs/architecture.md`](docs/architecture.md).
## What you actually get
- **A transparent sprite atlas** (`sprite-sheet-alpha.png`) — real alpha, no leftover chroma fringe, verified against white backgrounds ([why the extractor unmixes instead of peeling](docs/chroma-alpha.md)).
- **A runtime manifest** (`manifest.json.frame_layout`) — absolute frame rectangles, per-state fps and loop flags. Your engine samples rectangles; it never guesses a grid.
- **Breathe** — a still idle becomes a living loop, deterministic squash & stretch baked on your curated frames from one sidecar field, anatomy-aware and pixel-true ([details](docs/breathing.md)).
- **Pixel-art that stays on grid** — the Backbone Lattice measures one grid for the whole subject and holds every cut to it ([details](docs/pixel-unfake.md)).
- **Motion loops from video** — jumps get a tall canvas, attacks a wide one, the loop point is the clip's own period, and a one-shot action is cut rest → action → rest. Walk cycles count foot crossovers into a clean two-step loop with smoothed seams ([details](docs/video-pipeline.md)).
- **Deterministic colourways** — `recolor` bakes N variant sheets from a palette map; same input, same output bytes ([details](docs/recolor.md)).
- **QA you can watch** — per-state GIFs and contact sheets, so motion is judged as motion before anything ships. Cyclic locomotion (walk/run) stays experimental unless motion QA actually passes.
- **Independent asset tools** — build repeating backgrounds, project shadows from a foot anchor, and inspect timing, duplicate poses and contact evidence. Ambiguous feet produce an unverified measurement ([details](docs/asset-tools.md)).
- **Optional scene creation** — place existing PNGs, external frame sequences, loop strips or runtime atlases on named planes, with camera motion and shared shadow projection. Sprite generation can finish before this step ([details](docs/scene.md)).
## Quickstart
```bash
# install (Pillow, NumPy) into a fresh virtualenv — the venv is the only supported interpreter
python3 -m venv .venv && source .venv/bin/activate
pip install -e .
sprite-gen --help
```
**A · atlas rows** — one still to a runtime atlas.
```bash
sprite-gen prepare --out-dir <run> --character-id <id> --base-image base.png # request, guides, prompts
sprite-gen gen-set --run-dir <run> --provider codex # every state row, 4 at a time
sprite-gen extract --run-dir <run> # chroma → transparent frames
sprite-gen compose-atlas --run-dir <run> # sprite-sheet-alpha.png + manifest.json
sprite-gen curation --run-dir <run> # (optional) pick, nudge, breathe
```
**B · video → loop** — one still to transparent loops (needs `ffmpeg`, `img2webp`, and your own `grok` login or `XAI_API_KEY`). Walk and run loops have their jump frames repaired and a direction set shares one cycle length through RIFE: install it once with `sprite-gen rife install`. Without it those loops are cut as filmed, with a warning ([loop-repair](docs/loop-repair.md)).
```bash
sprite-gen video-set --base side=still.png --states idle,walk,run,jump,attack --out-dir set/
# per item: video-canvas → video → video-frames → video-loop; set/table.md names every result
```
Making clips through a video MCP connected to your agent? With ZCRE's (지크), the agent makes the clip on your own ZCRE account and sprite-gen cuts it: `sprite-gen video-prompt --direction side --state walk --no-last-frame` prints the prompt, then `video-frames` and `video-loop` take the mp4, and `video-cycle-align` gives a walk cut in several directions one cycle length. Walk, run and jump only, because ZCRE's Grok Imagine 1.5 has no end frame ([how](docs/video-pipeline.md#a-clip-from-a-video-mcp-on-your-agent--zcre)).
A watch on one wrist, a pin on one side of the head? Turned over, a right-facing view puts it on the other side, so draw the left-facing views instead: `sprite-gen gen --direction side --facing left --handed "the black smartwatch=left wrist"` says where the item is in that view, `video-set --facing right,left --handed …` films each side and diagonal view both ways from its own still, and `sprite-gen handed-check` checks, frame by frame, that a colour-marked item is on the right side. Mirroring stays the default, since drawing the left views costs as much again ([how](docs/video-pipeline.md#handedness--an-item-on-one-side)).
A title logo whose letters the model draws freely? `sprite-gen logo --provider codex --text "STARFALL" --style "painted fantasy" --out-dir logo/` letters the title into a title screen first, redraws only its lettering on a chroma key and cuts it out with its glow kept, then reads the text back and refuses a misspelt logo ([logo](docs/logo.md)).
**C · utilities** — each stands alone.
```bash
sprite-gen cutout icon.png --white-check # white/ivory → matte, magenta/green → chroma engine
sprite-gen slice-sheet --sheet sheet.png --chroma-key magenta --grid 3x2 # multi-figure sheet → per-cell cuts
sprite-gen unpack-atlas --atlas sheet.png # finished atlas → curator-ready run (or --pngs-dir folder/)
```
**D · post-processing** — refine a finished sheet without regenerating.
```bash
sprite-gen recolor-palette --base <run>/sprite-sheet-alpha.png --out palette.draft.json
sprite-gen recolor --run-dir <run> --spec recolor.spec.json # → <run>/variants/
sprite-gen export-aseprite --run-dir <run> # Aseprite JSON for Phaser / Flame
```
**E · asset tools** — each accepts existing assets, including artwork from other tools.
```bash
sprite-gen background-tile --source background.png --period 512 --overlap 32 --out tile.png
sprite-gen shadow --source walk.strip.json --out-dir shadows/
sprite-gen inspect-motion --source walk.strip.json --out motion.json
# Only with known same-foot contact and an isolated foot ROI:
sprite-gen inspect-motion --source walk.strip.json --contacts 0:4 --foot-box 20,70,32,10 --out stance.json
```
**S · scene** — an optional composition workflow. The [scene contract](docs/scene.md) includes a complete spec.
```bash
sprite-gen scene-render --spec scene.json --out-dir render/ --formats png,mp4 --export-layers
sprite-gen scene-inspect --spec scene.json --out scene-check.json
```
The agent-facing workflow, gates and contracts live in [`SKILL.md`](SKILL.md).
## Install as a skill
```bash
python3 ~/.codex/skills/.system/skill-installer/scripts/install-skill-from-github.py \
--repo aldegad/sprite-gen --path . --name sprite-gen
```
Image generation is part of this engine (`sprite_gen.gen`, providers `codex` and `grok` on a subscription you already pay for, plus an `openai` provider for servers and SaaS that bills per call and runs only when you chose it; the general `image-gen` skill is a thin shuttle over it). Every call uses **your own** credential, the subscription login first and an API key only without one, and nothing is shipped with the repo:
| Calls | First | Without it | Docs |
|---|---|---|---|
| `gen --provider codex` | the `codex` ChatGPT login | (a codex signed in with an API key bills that key) | [gen](docs/gen.md) |
| `gen --provider grok`, `video*` | the `grok` CLI login | `XAI_API_KEY` | [gen](docs/gen.md#direct-grok-calls-and-authentication), [video](docs/video.md) |
| `pixel-draw` | the `claude` (Claude Code) subscription login | `ANTHROPIC_API_KEY` | [pixel-draw](docs/pixel-draw.md#which-credential-a-call-runs-on) |
| `gen --provider openai` | — | `OPENAI_API_KEY`, only when you chose it | [gen](docs/gen.md#subscription-first--openai-runs-only-when-you-chose-it) |
A call on an API key is billed per call and says so on stderr before the request leaves, also inside `gen-set` and `video-set`. A call that names no provider runs on codex; when codex cannot run (not signed in, or its usage used up) it stops and asks (exit 75) — or runs what you chose for that with `sprite-gen defaults save --codex-unavailable grok|openai` ([gen](docs/gen.md#when-codex-cannot-run--ask-or-what-you-chose)). `logo` makes its images and its text checks through `gen`'s providers, on the same credentials.
`sprite-gen` supports CPython 3.11+; CI runs only 3.14. Python 3.10 is no longer supported. The quickstart needs a Python with working `venv`/`ensurepip`.
## Attribution
The component-row workflow is inspired by the Apache-2.0 licensed `hatch-pet` skill, but targets generic game sprite atlases and includes no pet packages or pet visual assets.
Community contributions, experiments, and their originating pull requests are documented in [`CONTRIBUTORS.md`](CONTRIBUTORS.md).
## License
Apache-2.0