gltf_opt

A Rust library for optimizing GLB (GL Transmission Format) files by resizing textures and optionally converting them to KTX2/Basis Universal format.

Description

This library provides functionality to optimize GLB files by:

• Resizing textures to reduce file size
• Converting textures to KTX2 format with Basis Universal compression for better performance
• Optionally removing normal textures to further reduce file size
• Repositioning model pivot point to bottom center

Features

• Resize textures to a specified dimension
• Convert textures to JPEG, PNG, or KTX2/Basis Universal format
• Remove normal textures to reduce file size
• Center pivot point to bottom center of the model (modifies vertex positions directly)
• Preserve GLB structure and other non-texture data
• Full support for skeleton/skin bindings and animations

Installation

Add this to your Cargo.toml:

[dependencies]
gltf_opt = { git = "https://github.com/AllenDang/gltf_opt" }

Usage

use gltf_opt::prelude::*;

// Assuming you have a GLB file loaded into a reader
let mut reader = /* your GLB file reader */;

// Optimize the GLB file:
// - new_texture_size: Target size for textures (e.g., 512 for 512x512)
// - remove_normal_texture: Whether to remove normal textures
// - convert_to_ktx2: Whether to convert textures to KTX2/Basis Universal format
// - center_pivot: Whether to move pivot point to bottom center
let optimized_glb = optimize(&mut reader, 512, false, true, false)?;

// Save the optimized GLB to a file
std::fs::write("optimized.glb", optimized_glb)?;

Parameters

• new_texture_size: The target size for resizing textures (textures will be resized to new_texture_size x new_texture_size)
• remove_normal_texture: If true, normal textures will be removed from the model
• convert_to_ktx2: If true, textures will be converted to KTX2 format with Basis Universal compression
• center_pivot: If true, the model's pivot point will be moved to the bottom center by modifying vertex positions

Notes

• Skinned/animated models: When a model contains skeleton/skin bindings or animations, the center_pivot option is automatically ignored to prevent incorrect deformation. Texture optimization is still applied normally.

Dependencies

• fast_image_resize: For fast image resizing
• gltf: For parsing GLTF/GLB files
• image: For image loading and encoding
• ktx2-rw: For KTX2 texture handling
• num_cpus: For detecting CPU count for parallel processing

License

MIT

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.