TexturePacker to Unity — JSON Atlas to Sprites and Clips
Unity's Sprite Editor can slice a sheet on a grid, but a packed atlas has frames of different sizes at arbitrary places, so the rects must come from the data file. Drop the TexturePacker PNG and JSON here and export for Unity 6: the bundle carries every rect and pivot already converted to Unity's conventions, plus an editor script that applies them and builds one AnimationClip per animation.
- Unity 6Verified· Unity 6000.5.3f1
- Godot 4Verified· Godot 4.7.2
- Phaser 3 / 4Verified· Phaser 3.90 + 4.2
- PixiJS 8Verified· PixiJS 8.21
- Aseprite JSONVerified· Phaser load.aseprite · PixiJS 8.21
- .asepriteVerified· Aseprite 1.3.18
- Spine / libGDXVerified· spine-canvas 4.2
- Starling / Sparrow XMLVerified· Phaser 4.2
- LÖVEVerified· LÖVE 11.5
- DefoldBuilt· Defold bob.jar 1.13.1
- GameMakerUNVERIFIED
- CSS spritesVerified· Chromium
- GIF / APNGDecoded· Pillow
What it does
- Rects converted to Unity's bottom-left origin (y = page height − y − h), one SpriteRect per frame, named after the frame.
- Pivots normalised inside each trimmed rect from the pivot on the full frame, so trimmed frames stay aligned; a value outside 0–1 is intended.
- Texture settings for pixel art: Sprite, Multiple, Point filter, Uncompressed, no mipmaps, Max Size raised until the page fits.
- Pixels Per Unit is a number in the JSON, 100 by default, and the script applies it; edit it before importing if your game uses another scale.
- One AnimationClip per animation: SpriteRenderer sprite keys at each frame's own start time, looping as tagged.
How to do it
- Drop the atlas PNG together with its JSON.
- Check the animations grouped from the frame names, then set pivots and durations on the Timeline.
- Open Pack & Export, choose Unity 6 and export.
- Copy the folder into Assets/ with its Editor folder; Unity compiles NerulioSpriteImporter.cs.
- Run Tools › Nerulio › Import Studio JSON and pick the .unity.json; the sprites appear on the texture and the .anim clips next to the JSON.
From TexturePacker JSON to Unity sprite settings
| JSON field | What the Unity importer sets | Why |
|---|---|---|
| frame {x, y, w, h} | SpriteRect with y = page height − (y + h) | Unity textures start at the bottom left |
| spriteSourceSize, sourceSize | pivot normalised inside the trimmed rect | every frame keeps one anchor point |
| pivot, or the one set with P | Custom alignment with that pivot | the character stands where it should |
| frame name | sprite name; animation from the name prefix | clips find their sprites by name |
| meta.size | Max Size raised to the next power of two that fits | Unity would otherwise shrink a large page |
| not in the JSON | Point, Uncompressed, no mipmaps, PPU 100 | crisp pixels; PPU editable in the JSON |
Engine exports and how each was checked
"Verified" means the exported files were loaded by the real engine or tool on real CC0 assets and the result was compared with the source. Anything that was not loaded is labelled as such.
| Target | Files | Check |
|---|---|---|
| Godot 4 | .tres SpriteFrames · .tscn AnimatedSprite2D · .png.import | Verified Godot 4.7.2Loaded by Godot; every animation frame drawn and compared with the source file. The scene uses Nearest filtering; rotation is never used. |
| Unity 6 | .unity.json · Editor/NerulioSpriteImporter.cs · AnimationClip | Verified Unity 6000.5.3f1Batch mode: sprite rects, pivots, pixels, clip keys and durations checked. |
| Phaser 3 / 4 | atlas JSON (multiatlas) · .anims.json | Verified Phaser 3.90 + 4.2Frames and animations drawn by both versions. |
| PixiJS 8 | spritesheet JSON · animations · anchor · meta.scale | Verified PixiJS 8.21Rotated and multi-page atlases included. |
| Aseprite JSON | hash / array · frameTags · slices | Verified Phaser load.aseprite · PixiJS 8.21Tags keep their direction and repeat count. |
| .aseprite | layers · tags · durations · slices | Verified Aseprite 1.3.18Opened and rendered by the Aseprite command line. |
| Spine / libGDX | .atlas | Verified spine-canvas 4.2Every region drawn by the Spine runtime, rotated and trimmed; libGDX itself was not run. |
| Starling / Sparrow XML | XML per page | Verified Phaser 4.2Phaser 3.90 draws trimmed XML frames wrongly (its own bug); the "Sparrow XML (Phaser 3)" preset turns trim off and passes in 3.90 and 4.2. |
| LÖVE | Lua quads · nerulio_atlas.lua · main.lua | Verified LÖVE 11.5Every frame drawn and every animation stepped through the shipped helper. |
| Defold | .atlas · .tilesource | Built Defold bob.jar 1.13.1Built by Defold's command-line builder; the built texture's UVs were read back. |
| GameMaker | spr_<name>_stripN.png · gamemaker.json | UNVERIFIEDNot loaded in GameMaker (no headless GameMaker). The strips are cut the way its strip importer cuts them. |
| CSS sprites | .css · preview .html | Verified ChromiumEvery class drawn from the shipped stylesheet. |
| GIF / APNG | one file per animation | Decoded PillowEvery frame and delay decoded again after export; APNG is exact. |
Evidence
GIF decoder: 408 of 408 frames identical to Pillow on 29 real GIFs; APNG 132 of 132 on 16 files. .aseprite: 231 corpus files imported, re-written and reopened in Aseprite 1.3.18 with the same tags, durations and pixels (231/231). Exports: 49 runs in the real engines on real CC0 assets, 47 pass — the 2 failures are Phaser 3.90's trimmed-XML bug, which the Phaser 3 preset avoids.
Limits
- A grid or island guess is a preview with a confidence; nothing is cut until you press Apply, and every choice has one-click alternatives.
- .aseprite files whose layers do not compose exactly (e.g. group opacity) are imported flattened, and the Import panel says why.
- Rotated frames in an imported atlas stay rotated; their export is UNVERIFIED.
- Images up to 32,768 px per side (268 million pixels), subject to your browser's memory.
Questions
Do I need a TexturePacker importer in Unity?
No. The bundle brings its own editor script and needs only the 2D Sprite package (com.unity.2d.sprite) that the 2D templates include. Unity 6000.5.3f1 in batch mode ran it and read back rects, pivots, pixels, clip keys and durations.
Do my hitboxes reach Unity?
Not through this importer: a Unity sprite has no field for them. Boxes and collision polygons go into the Generic JSON export instead, and the Unity export tells you so.
My JSON has rotated frames. Can I still use it?
They import still turned and exporting them is UNVERIFIED; the Unity target itself refuses a rotated pack. Pack again in TexturePacker with rotation disabled and drop the new pair of files.
Is it free, and do I need an account?
Everything on these pages is free and works without an account. There is no watermark and no export that is held back.
Are my sprites uploaded?
No. The Studio decodes, packs and exports in this browser tab. Projects are autosaved in the browser (IndexedDB) and can be saved as a .nerulio file.
Does it need Aseprite or an engine plugin installed?
No. .aseprite files are read and written in the browser, and each engine bundle carries what that engine needs (for Godot, the import settings and scene; for Unity and the Godot TileSet, a small editor script).