Unity3D Fleet Mesh — Skill Guide

Unity3D Fleet Mesh — Skill Guide

You have access to unity3d-mcp, a FastMCP 3.2 server that bridges Unity 3D to the fleet mesh. This guide covers how to use the import/export pipeline across formats and connected repos.

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Quick reference

Unity3D-MCP sits at the center of the fleet visualization layer:

Gazebo (physics) ──FBX──▶  │        │──FBX──▶ Blender (modelling)
FreeCAD (CAD)    ──STEP─▶  │ Unity  │──FBX──▶ Gazebo (sim mesh)
Resonite (VR)    ──GLB──▶  │  3D    │──glTF─▶ Web/mobile
Blender (scenes) ──FBX──▶  │  MCP   │──glTF─▶ Resonite VR
World Labs (AI)  ──OBJ──▶  │        │

Import pipeline

Every import endpoint accepts the same body:

{"models": ["name1", "name2"], "file_path": "optional/path/{model}.fbx"}

If no file_path is given, the server searches {source}_models/{model} with extensions .fbx, .obj, .gltf, .glb, .stl, .step, .vrm.

From Gazebo (POST /api/v1/gazebo/import)

Gazebo exports robot models and environment meshes as FBX. Typical workflow:

1. gz_sim_state() to list models in the simulation
2. Run the simulation — let the robot drive around
3. Export the scene from Gazebo: gz topic -t /world/scene --msgtype gz.msgs.Scene --reptype gz.msgs.Scene --reqtype gz.msgs.Empty --req "" --timeout 2000
4. Import into Unity via this endpoint
5. The imported model appears in the Unity scene immediately

Use case: Visualizing a Gazebo robot simulation in high-fidelity Unity rendering. Camera paths, lighting, materials all look better in Unity than in Gazebo's default viewport.

From FreeCAD (POST /api/v1/freecad/import)

FreeCAD exports mechanical parts as STEP or STL. Typical workflow:

1. Design a part in FreeCAD (or via freecad-mcp)
2. Export as STEP (preferred) or STL
3. Import into Unity via this endpoint
4. The part appears as a Unity mesh with correct scale

Use case: Robot parts designed in CAD appear in the Unity scene alongside the simulated robot from Gazebo. Validate fit and form before 3D printing.

From Resonite (POST /api/v1/resonite/import)

Resonite exports avatars as VRM and worlds as GLB. Typical workflow:

1. Build a world or avatar in Resonite VR
2. Export as VRM (avatar) or GLB (world)
3. Import into Unity via this endpoint
4. The VRM avatar appears with rigging; the GLB world appears as a scene

Use case: VR-designed content from Resonite flows into Unity for higher-fidelity rendering or combined scenes.

From Blender (POST /api/v1/blender/import)

Blender exports scenes as FBX or GLTF. Typical workflow:

1. Model in Blender (or via blender-mcp)
2. Export as FBX (for animation/rigging) or GLTF (for web/Resonite)
3. Import into Unity via this endpoint

From World Labs (POST /api/v1/worldlabs/import)

World Labs Marble generates OBJ/FBX/GLB worlds from text prompts. Typical workflow:

1. Generate a world via worldlabs-mcp
2. Download the export files
3. Import into Unity via this endpoint

Export pipeline

To FBX (POST /api/v1/export/fbx)

Best for: Blender, Gazebo, FreeCAD, any traditional 3D app.

Preserves: Hierarchy, transforms, materials, animation (Unity Animator Controller paths).

{"name": "MyModel", "output_path": "exports/MyModel.fbx"}

To glTF (POST /api/v1/export/gltf)

Best for: Web (Three.js, react-three-fiber), mobile apps, Resonite VR.

glTF is the "JPEG of 3D" — compact, PBR materials, no proprietary licensing. The GLB variant (single binary file) is especially convenient.

{"name": "MyModel", "output_path": "exports/MyModel.glb"}

When to use glTF vs FBX:

Factor	FBX	glTF
File size	Large	Small (often 10x smaller)
Animation	Full (bones, blendshapes)	Full
Materials	Standard Unity	PBR (metalness/roughness)
Open standard	No (Autodesk)	Yes (Khronos)
Browser/web	Requires converter	Native support
Resonite VR	Requires converter	Native (.glb)
Unity import	Native	Native (2020+)

Format guide

Extension	Format	Can read	Can write	Animations	Use when
.fbx	Autodesk FBX	✅	✅	✅	Full scene exchange with Blender/Gazebo
.gltf/.glb	glTF / GLB	✅	✅	✅	Web, mobile, Resonite, delivery
.obj	Wavefront OBJ	✅	❌	❌	Universal fallback, no animation needed
.stl	Stereolithography	✅	❌	❌	3D printing
.step/.stp	ISO 10303 STEP	✅	❌	❌	Engineering CAD, FreeCAD exchange
.vrm	VRM avatar	✅	❌	✅	Humanoid avatars for Resonite/VRChat
.unitypackage	Unity package	✅	✅	✅	Internal Unity asset sharing

Fleet mesh workflows

Simulation-to-visualization (Gazebo → Unity)

gz_sim_state() → identify models
gz_topic_pub() → run simulation, export frames
POST /api/v1/gazebo/import → import models into Unity

CAD-to-simulation (FreeCAD → Unity → Gazebo)

freecad-mcp export → STEP file
POST /api/v1/freecad/import → import into Unity for visualization
Validate fit and form in rendered scene
Export back to FBX → Gazebo for physics

VR-to-render (Resonite → Unity → web)

resonite-mcp export → GLB/VRM
POST /api/v1/resonite/import → import into Unity
Add lighting, materials, post-processing in Unity
POST /api/v1/export/gltf → export for web delivery

AI-worlds-to-scene (World Labs → Unity)

worldlabs-mcp generate → OBJ/FBX files
POST /api/v1/worldlabs/import → import into Unity scene
Composite with other elements (robots from Gazebo, parts from FreeCAD)

Common issues

• "Model file not found" — File path is wrong or the format isn't supported. Check file_path ends with a known extension. Use /import/model for auto-detection.
• "FBX with animation not importing" — Unity FBX import might strip animation if the exporter settings don't include include_animation. Use glTF for simpler animation transfer.
• "glTF looks different in Unity vs source" — Unity imports glTF materials as Standard (Metallic) by default. If source uses different PBR parameters, materials may shift slightly. This is expected.
• "VRM avatar losing rigging" — Ensure the VRM file is standard VRM 0.x or 1.0. Non-standard or damaged VRMs may import as static meshes.