blender-to-unity

name	blender-to-unity
description	Hand off a model from Blender (via BlenderMCP) into Unity (via MCP for Unity) — export the current Blender model, import it through import_model_file, and place it in the open scene. Use when the user has BlenderMCP and MCP for Unity both connected and wants to bring a Blender model into Unity. Does NOT drive Blender's own generators; BlenderMCP owns how the model got into Blender.

Blender → Unity Model Handoff

Bring whatever model is currently in Blender into the open Unity scene. The seam is the local filesystem: Blender exports a file, Unity imports it. The two servers never talk directly.

Preconditions

• Both mcp__blender__* tools and MCP for Unity tools are connected.
• A model exists in the Blender scene (confirm with mcp__blender__get_scene_info / mcp__blender__get_object_info). If empty, stop and tell the user — this skill does not generate models.

Steps

1. Resolve the Unity project path. Read mcpforunity://editor/state for the project root (the editor dataPath's parent). Decide the export format: FBX by default (built-in importer, zero extra dependencies). Use glTF/.glb only if glTFast is installed and PBR fidelity matters.
2. Export from Blender to a temp path via mcp__blender__execute_blender_code:

   import bpy, os, tempfile
   out = os.path.join(tempfile.gettempdir(), "blender_to_unity.fbx")
   # Export the selection if any, else the whole scene:
   bpy.ops.export_scene.fbx(filepath=out, use_selection=bool(bpy.context.selected_objects),
                            apply_unit_scale=True, bake_space_transform=True)
   print(out)
   

   (glTF branch: bpy.ops.export_scene.gltf(filepath=out_glb, export_format='GLB').)
3. Import into Unity with import_model_file: import_model_file(source_path=<temp path>, name=<asset name>, target_size=<final size in meters>). It returns { asset_path, asset_guid }. Pass target_size as the intended final size, but treat it only as a hint: it rescales at import solely when the project's Auto-normalize pref is on, and even then is unreliable for Blender FBX (see the Scale note). Step 4 does the reliable normalization.
4. Place it in the scene, normalized to size. Ensure the scene has a camera + directional light (manage_scene / manage_gameobject). Instantiate the model at the chosen position via manage_gameobject(action="create", prefab_path=<asset_path>, name=<asset name>, position=[x,y,z]). Then normalize its size deterministically — Blender FBX commonly imports ~100× too large — by measuring the placed model's world bounds and scaling so its largest dimension equals your target size. Run via execute_code (substitute your object name and target meters):

   var go = GameObject.Find("<asset name>");
   var rs = go.GetComponentsInChildren<Renderer>();
   var b = rs[0].bounds; for (int i = 1; i < rs.Length; i++) b.Encapsulate(rs[i].bounds);
   float maxDim = Mathf.Max(b.size.x, Mathf.Max(b.size.y, b.size.z));
   float target = 2f; // intended size in meters
   if (maxDim > 0.0001f) go.transform.localScale *= target / maxDim;
   

5. Verify with manage_camera(action="screenshot", include_image=true) and report the asset path + a screenshot.

Notes

• Scale. Models from Blender almost always arrive at the wrong scale — its FBX unit handling makes them land ~100× too large in Unity. import_model_file's target_size only rescales at import when the project's Auto-normalize pref is enabled, and its importer-level normalization is unreliable for Blender FBX (it can over- or under-shoot, e.g. a target_size=2 model measured 200 m). The robust fix is the Step 4 measure-bounds-then-set-localScale routine, which hits the target size deterministically regardless of the import scale or the Auto-normalize pref.
• FBX is the default because glTFast is optional in MCP for Unity. If the import errors with "GLB import requires glTFast", re-export as FBX (or install glTFast from the Dependencies tab).
• Keep one model per handoff; for batches, repeat the loop with distinct names.
• This skill never sends API keys or file bytes over the MCP bridge — Unity reads the file from disk.
• import_model_file copies only the single source file; for multi-file exports (a text .gltf with an external .bin, or an .obj with a sibling .mtl/textures), zip them first and pass the .zip — a bare .gltf/.obj will lose its sidecars.