> For the complete documentation index, see [llms.txt](https://docs.m-xr.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.m-xr.com/marso-studio/preparing-your-assets/3d-file-support.md).

# 3D file support

## 3D file support

Marso Studio accepts **GLB**, **USD** and **FBX** uploads. GLB and USD are the most mature paths today. **FBX is the newest format we accept and carries the highest risk of import or generation errors.**

> **Every format needs an image-based base-colour texture mapped to the geometry.** Vertex colours are *not* textures, and assets coloured with vertex data alone will be rejected.

### Requirements by format

#### GLB *(recommended)*

| GLB upload                                        | Accepted? |
| ------------------------------------------------- | :-------: |
| Textures embedded in the file                     |     ✅     |
| A base-colour texture on every material           |     ✅     |
| Textures referenced externally (URI or file path) |     ❌     |
| A material with no texture                        |     ❌     |

GLB has the strictest texture rules — see What gets a GLB rejected for the detail.

#### USD

Package as **`.usdz`** with geometry and a base-colour texture.

| USD upload                                                                | Accepted? |
| ------------------------------------------------------------------------- | :-------: |
| Textures embedded *or* referenced inside the package — we re-resolve them |     ✅     |
| Geometry with no base-colour texture                                      |     ❌     |

#### FBX

Either embed the textures inside the `.fbx`, **or** zip the `.fbx` together with its texture files.

| FBX upload                                              | Accepted? |
| ------------------------------------------------------- | :-------: |
| Textures embedded in the `.fbx`, or zipped alongside it |     ✅     |
| Base-colour map named by convention (see below)         |     ✅     |
| A zip that doesn't follow the naming convention         |     ❌     |
| External textures not bundled in the zip                |     ❌     |

**Base-colour naming convention:** name the map `game.color.png`, `color.png`, `albedo.png`, `basecolor.png`, or `base_color.png`.

### Supported model features

These all work, across your uploads:

| Feature                 | Supported? | What it means                                                                                                          |
| ----------------------- | :--------: | ---------------------------------------------------------------------------------------------------------------------- |
| **Multi-mesh**          |      ✅     | Multiple separate objects in one file (e.g. a table and a chair).                                                      |
| **Multi-material**      |      ✅     | Different parts of your model can use different materials (e.g. one shiny, one matte).                                 |
| **Texture atlasing**    |      ✅     | Pack multiple materials' textures into one image — as long as each material's UVs occupy a distinct region of it.      |
| **Adjacent UV regions** |      ✅     | Two materials' UV regions can touch along a shared edge (e.g. left half and right half) — touching is not overlapping. |

### What gets a GLB rejected

GLB uploads must be fully self-contained. We reject:

| Issue                                         | Why we reject it                                                                                                |
| --------------------------------------------- | --------------------------------------------------------------------------------------------------------------- |
| **External textures**                         | The GLB must embed every texture. GLBs that reference textures by external URL or filename are rejected.        |
| **Untextured materials**                      | Every material must have at least one texture (base colour, normal, metallic-roughness, occlusion or emissive). |
| **Broken texture references**                 | Texture slots pointing to a missing texture, missing image, or empty image data are rejected.                   |
| **A separate texture file alongside the GLB** | Embedded textures are the source of truth — sending a GLB plus a loose texture file is rejected.                |

### Good to know

Allowed by the validator today, but worth watching:

* **Tiled / out-of-`[0,1]` UVs.** UVs are read as raw values, not wrapped into the `[0,1]` square. A material whose UVs run `0`–`5` (to tile a texture) is treated as occupying that whole `0–5` range and will very likely collide with another material — so tiling-style UVs are effectively unsupported.

***

File requirements are only half the story — getting a *good* result also depends on the kind of asset you bring. See [Sourcing & preparing assets](/marso-studio/preparing-your-assets/sourcing-and-preparing-assets.md).


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