dmitsuki / gltf2

Native Odin implementation of glTF2 loading file format as described by khronos: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html

Why another glTF2 library?

1. I want to learn Odin because I like philosophy behind it and syntax. I also tried Zig for few weeks, but it's syntax is not compelling to me.
2. I don't like cgltf implementation in vendor:cgltf and it doesn't work on *Nix based systems (for now), only on Windows.
3. Odin has built-in many great native packages like core/encoding/json so why not write glTF file format package that uses Odin types and remove C hint fields from cgltf wrapper?
4. Learning how to implement specification document into working code. In this case it's glTF2
5. Because it's fun.

Progress

✔️ - fully implemented ➕ - partially implemented ❌ - not implemented

Type	Status	Details	Specification URL
Accessors	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-accessor
Animations	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-animation
Asset	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-asset
Buffers	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-buffer
Buffer Views	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-bufferview
Cameras	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-camera
Images	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-image
Materials	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-material
Meshes	➕	Missing mesh primitive targets	https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-mesh
Nodes	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-node
Samplers	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-sampler
Scene	✔️	It's just an integer
Scenes	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-scene
Skins	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-skin
Textures	✔️		https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-texture
Extensions	✔️	Represented as JSON.Value	https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-extension
Extensions Used	✔️	Array of strings
Extensions Required	✔️	Array of strings
Extras	✔️	Represented as JSON.Value	https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-extras

How to use it

1. Download glTF2 package from github and put in your source folder.
2. Load entire glTF2 file into memory (simplest way).

import "gltf2"

main :: proc() {
    // This procedure sets file format from file extension [gltf/glb]
    data, error := gltf2.load_from_file("file_name.[gltf/glb]")
    switch err in error {
    case gltf2.JSON_Error: // handle json parsing errors
    case gltf2.GLTF_Error: // handle gltf2 parsing errors
    }
    // if there are no errors we want to free memory when we are done with processing gltf/glb file.
    defer gltf2.unload(data)

    // do stuff with 'data'
    ...

    // Iterate over buffer elements using accessor:
    for it := gltf2.buf_iter_make([3]f32, &data.accessors[0], data); it.idx < it.count; it.idx += 1 {
        fmt.printf("Index: %v = %v\n", it.idx, gltf2.buf_iter_elem(&it))
    }
}

3. Load parts of file into memory and parse itself. It can be handy if you can't load entire file into memory.

import "gltf2"

main :: proc () {
    // Set options for gltf2 parser.
    // is_glb must be set to true if file is in binary format. Most likely it will have "*.glb" suffix. By default it's gltf or JSON file format.
    // delete_content set to true will delete bytes provided in procedure call. This is what 'load_from_file' does.
    // parse_uris will try to parse all URI links, this will take CPU time to do so it's not default option.
    options := gltf2.Options{ is_glb = [true/false(default)], delete_content = [true/false(default)], parse_uris = [true/false(default)] }

    // Load some part of file that is valid JSON object
    data, error := gltf2.parse(bytes, options)
    switch err in error {
    case gltf2.JSON_Error: // Handle JSON parsing errors
    case gltf2.GLTF_Error: // Handle GLTF2 parsing errors
    }
    // If there are no errors we want to free memory when we are done with processing gltf/glb file.
    defer gltf2.unload(data)
}

How You can help.

1. Implement missing functionality (package is still missing some stuff).
2. Remove bugs (they are for sure).
3. Optimize code.