draco-gltf

Lossless glTF 2.0 and pinned 2.1-draft scene handling with optional KHR_draco_mesh_compression geometry.

use draco_gltf::{MeshIndex, PrimitiveIndex};

let scene = draco_gltf::import("model.glb")?;
let geometry = scene.read_primitive(PrimitiveIndex::new(MeshIndex(0), 0))?;
println!("{} vertices", geometry.vertex_count());
# Ok::<(), draco_gltf::Error>(())

Import owns a lossless Document, resolved resources and container provenance. Typed views cover complete scenes, while unknown properties, extras, extension JSON and draft fields survive edits and serialization. Document::to_json_bytes retains untouched source bytes; to_minified_json_bytes explicitly emits whitespace-free JSON while retaining object order and number lexemes.

PackedGeometry is the shared primitive boundary for read and write APIs. Import::read_primitive reads ordinary accessors or decodes Draco. With feature write, write_primitive, push_primitive, and from_geometry write the same value back as ordinary accessors. Feature draco-encode additionally allows GeometryEncoding::Draco; Draco-only is explicit and fallback storage must also be selected explicitly.

use draco_gltf::{
    GeometryWriteOptions, Import, OutputFormat, ValidationProfile,
};
# let geometry = todo!();
let scene = Import::from_geometry(
    &geometry,
    ValidationProfile::Gltf20,
    GeometryWriteOptions::default(),
)?;
let glb = scene.to_bytes(OutputFormat::GlbV2)?;
# Ok::<(), draco_gltf::Error>(())

Raw writing preserves profile-valid glTF 2.1 scalar storage such as f16, f64, i64, and u64. Draco encoding never normalizes or casts unsupported types: it returns a typed error instead. Primitive writes are atomic, do not mutate shared accessors in place, and preserve material, extras, morph targets with compatible counts, and unrelated extensions. Generated POSITION accessors include exact min/max bounds for every supported scalar type.

For portable .gltf output, Import::to_gltf_output returns JSON plus named companion resources. Import::to_bytes emits JSON without new companions or a self-contained GLB v2/v3. Explicit glTF 2.1 files loading remains controlled by the caller and resource limits.

Features

• document: lossless DOM, typed views, containers and serialization.
• geometry: accessor materialization and PackedGeometry.
• draco-decode: KHR_draco_mesh_compression decoding.
• resources: explicit URI and files resolution.
• strict-validation: strict scene-reference, node-tree, and POSITION-bounds validation.
• read: ordinary primitive reading with resources and validation.
• accessors: generic accessor materialization, including matrix accessors.
• write: raw geometry construction and document mutation.
• draco-encode: Draco writing; depends on write and draco-decode.
• full: the default complete profile.

Use default-features = false, features = ["read", "draco-decode"] for a small Draco-capable reader. Add strict-validation when opening untrusted assets requires a full graph pass, write for raw output or draco-encode for compressed output, and accessors when animation, skin, morph, or other non-primitive payloads must be materialized. Every profile uses the same document and packed-geometry types; no second parser or scene model exists.

See GLTF_2_1_SUPPORT.md for the support matrix and upstream links. GLTF_2_1_SNAPSHOT.md records the pinned draft and update policy.

License

Apache-2.0.