/gltf-transform

name: gltf-transform
description: Optimize and post-process GLB/glTF 3D models. Use when compressing models for web delivery, reducing file size, simplifying geometry, inspecting model stats, merging models, or converting textures. Triggers on: optimize GLB, compress model, reduce file size, simplify mesh, draco compression, meshopt, webp textures, inspect model, merge GLB, model optimization.

glTF Transform

Post-process GLB/glTF files: optimize, compress, inspect, and transform 3D models.

• CLI docs: https://gltf-transform.dev/cli
• GitHub: https://github.com/donmccurdy/glTF-Transform
• npm: `@gltf-transform/cli`

Zero-Setup with bunx

No installation required. Run any command with:

bunx @gltf-transform/cli <command> [args]

First run downloads the tool, subsequent runs are instant.

Quick Start

# Inspect model stats first
bunx @gltf-transform/cli inspect model.glb

# One-command optimization (good defaults)
bunx @gltf-transform/cli optimize input.glb output.glb --compress draco --texture-compress webp

CAD Workflow Integration

Typical pipeline after generating models with build123d:

create geometry → export GLB → optimize → verify visually

1. **build123d** exports high-quality CAD geometry 2. **gltf-transform** compresses for web delivery 3. **render-glb** verifies the result

Compression Methods

| Method | Best For | Trade-offs | |--------|----------|------------| | **Draco** | Web delivery, Three.js | Smallest geometry, requires decoder | | **Meshopt** | Universal, animations | Good compression + animation support | | **Quantize** | Compatibility | No decoder needed, moderate compression |

# Draco - best geometry compression
bunx @gltf-transform/cli draco input.glb output.glb

# Meshopt - geometry + animation compression
bunx @gltf-transform/cli meshopt input.glb output.glb

# Quantize only - no external decoder needed
bunx @gltf-transform/cli quantize input.glb output.glb

Texture Compression

# WebP - good compression, wide browser support
bunx @gltf-transform/cli webp input.glb output.glb

# Resize large textures
bunx @gltf-transform/cli resize input.glb output.glb --width 1024 --height 1024

Common Operations

Inspect Model Stats

bunx @gltf-transform/cli inspect model.glb

Shows vertex count, file size breakdown, texture sizes - helps decide what to optimize.

Simplify Geometry

# Weld duplicate vertices first
bunx @gltf-transform/cli weld input.glb temp.glb

# Then simplify
bunx @gltf-transform/cli simplify temp.glb output.glb --ratio 0.5

Useful for CAD models which often have more detail than needed for web viewing.

Merge Multiple Models

bunx @gltf-transform/cli merge part1.glb part2.glb assembly.glb

Aggressive Optimization

bunx @gltf-transform/cli optimize input.glb output.glb \
  --compress draco \
  --texture-compress webp \
  --simplify true \
  --simplify-ratio 0.5

When to Use

| Scenario | Commands | |----------|----------| | Web delivery | `optimize --compress draco --texture-compress webp` | | Check model stats | `inspect` | | High-poly CAD model | `weld` then `simplify --ratio 0.5` | | Combine parts | `merge` | | Debug issues | `inspect` then targeted fixes |