AVP Animation Exporter Pro

A Blender addon for exporting skeletal animations to USDZ format, optimized for Apple Vision Pro and Reality Composer Pro.

The Problem

Blender's built-in USD exporter has issues with skeletal animations:

• Multiple actions don't concatenate properly into a single timeline
• NLA tracks can interfere with export
• Animation bindings are sometimes missing in the output

This addon solves these problems by properly baking all your animations into a single timeline and exporting a clean USDZ that works reliably in visionOS apps.

Features

• Visual Animation Manager — See all actions with frame counts and durations
• Selective Export — Choose which animations to include via checkboxes
• Animation Preview — Preview any animation directly in the viewport
• Two Export Modes — Baked (recommended) or NLA-based export
• Auto-Detection — Finds armatures automatically, even when a mesh is selected
• Animation Map Output — Generates JSON and/or text files with frame ranges
• Quick Re-Export — One-click re-export with previous settings
• Mesh Tools — Flip and recalculate normals for fixing inside-out models
• Axis Conversion — Automatic Z-up to Y-up conversion for visionOS
• Detailed Logging — See exactly what's happening during export

Installation

1. Download avp_animation_exporter_v3.py
2. Open Blender → Edit → Preferences → Add-ons
3. Click Install... and select the downloaded file
4. Enable the checkbox next to "AVP Animation Exporter Pro"
5. Save preferences to keep it enabled

Usage

Basic Workflow

1. Select your character mesh or armature
2. Press N in the 3D Viewport to open the sidebar
3. Click the AVP Export tab
4. Click Refresh Actions to scan for animations
5. Check/uncheck animations you want to export
6. Click Export USD

Alternative: File Menu

You can also access the exporter via File → Export → USD for AVP (.usdz)

Panel Overview

Main Panel

Shows the selected object, associated armature, active action, and mesh count.

Mesh Tools Panel

Tools for fixing common mesh issues before export.

Tool	Description
Flip Normals	Invert the direction of normals on selected faces
Recalculate Outside	Make normals face outward (standard for solid objects)
Recalculate Inside	Make normals face inward (for rooms/interiors)

• In Edit Mode: affects only selected faces
• In Object Mode: affects all faces on the mesh

Tip: If your model appears inside-out or invisible in visionOS, try flipping or recalculating the normals.

Animations Panel

Lists all detected actions with:

• Checkbox to include/exclude from export
• Animation name
• Frame count and duration
• Select All / Deselect All buttons

Preview Panel

• Preview any animation by selecting it and clicking Preview Selected
• Loops the animation and sets the timeline to match
• Click Stop Preview when done

Export Settings Panel

Export Mode

Mode	Description	Best For
Baked Action	Bakes all animations into a single action with keyframes on every frame	Maximum compatibility, recommended for visionOS
NLA Track	Exports using NLA track structure	Preserving action organization

Options

Setting	Description	Default
Frame Padding	Gap between animations in frames	10
Use Object Name	Name output file after the armature	On
Delete Temp Track	Clean up temporary data after export	On
Selected Only	Export only armature and its meshes	On
Export Materials	Include materials in USD	On
Export Textures	Include textures in USD	On
Export Shape Keys	Include blend shapes	On

Output Files

Setting	Description
JSON Animation Map	Detailed JSON with frame ranges, durations, FPS
AnimRanges.txt	Human-readable text file with frame ranges

Axis Conversion Panel

Blender uses a Z-up coordinate system, while visionOS/Reality Composer Pro uses Y-up. This panel handles the conversion automatically.

Setting	Description	Default
Convert Orientation	Enable coordinate system conversion	On
Forward Axis	The forward direction in the exported file	Z
Up Axis	The up direction in the exported file	Y

Presets:

• visionOS — Sets Forward: Z, Up: Y (recommended for Apple Vision Pro)
• Blender Default — Disables conversion, keeps Z-up

Note: The defaults are already configured for visionOS. Most users won't need to change these settings unless importing assets from other software with different conventions.

Log Panel

Expandable panel showing export progress and any warnings/errors.

Output Files

After export, you'll have:

MyCharacter.usdz           # The animated model
MyCharacter_animmap.json   # Machine-readable animation data
MyCharacter_AnimRanges.txt # Human-readable frame ranges

JSON Animation Map Format

{
  "fps": 24,
  "padding": 10,
  "count": 5,
  "length": 500,
  "duration": 20.83,
  "export_mode": "BAKED",
  "views": {
    "Idle": {
      "name": "Idle",
      "start": 1,
      "end": 101,
      "length": 100,
      "duration": 4.17
    },
    "Walk": {
      "name": "Walk",
      "start": 111,
      "end": 151,
      "length": 40,
      "duration": 1.67
    }
  }
}

AnimRanges.txt Format

Animation Ranges for Arm_Character
==================================================

FPS: 24
Total Frames: 500
Total Duration: 20.83s
Export Mode: BAKED

--------------------------------------------------

Idle: frames 1–101 (100f, 4.17s)
Walk: frames 111–151 (40f, 1.67s)
Run: frames 161–189 (28f, 1.17s)

Using in visionOS / Reality Composer Pro

Playing a Specific Animation

Use the animation map to play specific animations by seeking to their frame range:

// Load your entity with the animation
let entity = try await Entity(named: "MyCharacter", in: realityKitBundle)

// Get animation resource
guard let animation = entity.availableAnimations.first else { return }

// Calculate time for "Walk" animation (starts at frame 111, 24 FPS)
let walkStartTime = 111.0 / 24.0  // 4.625 seconds

// Play from that point
var controller = entity.playAnimation(animation)
controller.time = walkStartTime

Animation Map Loader (Swift)

struct AnimationRange: Codable {
    let name: String
    let start: Int
    let end: Int
    let length: Int
    let duration: Double
}

struct AnimationMap: Codable {
    let fps: Double
    let padding: Int
    let count: Int
    let length: Int
    let duration: Double
    let views: [String: AnimationRange]
}

// Load and parse
let mapURL = Bundle.main.url(forResource: "MyCharacter_animmap", withExtension: "json")!
let data = try Data(contentsOf: mapURL)
let animMap = try JSONDecoder().decode(AnimationMap.self, from: data)

// Get a specific animation's start time
let walkAnim = animMap.views["Walk"]!
let startTime = Double(walkAnim.start) / animMap.fps

Troubleshooting

"No actions found"

• Make sure your armature has actions in the Action Editor
• Actions shorter than the minimum frame length (default: 5) are skipped
• The baked action name is excluded from the list

Exported USDZ doesn't animate

• Use Baked Action mode (default)
• Ensure the armature is selected or a mesh with an armature modifier
• Check the log panel for errors

Animation looks wrong

• Verify animations play correctly in Blender first
• Try increasing frame padding if animations blend together
• Check that bone names don't have special characters

Missing meshes in export

• Enable Selected Only and make sure meshes are selected
• Or disable Selected Only to export everything

Export fails with TypeError

• The addon has fallbacks for different Blender versions
• If issues persist, try Blender 3.6 LTS or newer

Requirements

• Blender 3.0 or newer (3.6 LTS recommended)
• No external dependencies for basic functionality

Optional: Animation Binding Fix

If animations still don't play after export (rare with Baked mode), enable Fix Animation Binding in settings. This requires the usd-core Python package:

# In Blender's Python console:
import subprocess, sys
subprocess.check_call([sys.executable, "-m", "pip", "install", "usd-core"])

License

MIT License — feel free to use, modify, and distribute.

Contributing

Issues and pull requests welcome! Please include:

• Blender version
• Steps to reproduce
• Sample .blend file if possible

Credits

Contributors

• Mike Bundy — Main contributor X (@mikebundy) | LinkedIn

• Andrew Edwards LinkedIn | Mastodon (@platformgoblin)

Special Mentions

Thanks to the following people for their generous lessons on animations and Blender:

• Steve Talkowski — LinkedIn
• Mathew Spendlove — LinkedIn

Acknowledgments

• Built for the Apple Vision Pro developer community
• Inspired by the challenges of getting skeletal animations into visionOS
• Thanks to everyone who reported issues and tested fixes