# Resource formats

## Dictionary format

```
[kkkk vvvv KK... VV...]...
 ^    ^    ^     ^
 |    |    |     | value
 |    |    | key
 |    | 16-bit kalue length
 | 16-bit key length
```

## PrefabIndex

| Key      | Value Type |
| -------- | ---------- |
| \<Name\> | `Res`      |

## Prefab

| Key           | Value Type                             |           |
| ------------- | -------------------------------------- | --------- |
| `mesh`        | `Matrix3`, `Vec3`, `Res<MeshPart>`     | Multi key |
| `collision`   | `Matrix3`, `Vec3`, `Res<ColliderPart>` | Multi key |
| `light`       | `Vec3`, `Res<LightPart>`               | Multi key |
| `environment` | `Res<EnvironmentPart>`                 |           |

## MeshPart

Vertex attribute arrays (va_\*) are resources that contain a packed float32
array. ombinations of g_\*, va_\* and tex_\* are multiplied except normal which
is added. Defaults should be the identity for that operation, so default is 1 /
white except normals are zero.

| Key                  | Value Type     |                    |
| -------------------- | -------------- | ------------------ |
| `name`               | `String`       |                    |
| `index`              | `Res`          |                    |
| `g_metallic`         | `Float`        |                    |
| `g_roughness`        | `Float`        |                    |
| `g_albedo`           | `Vec3`         |                    |
| `g_alpha`            | `Float`        |                    |
| `g_transmission`     | `Float`        |                    |
| `g_emission`         | `Vec3`         |                    |
| `g_refractive_index` | `Float`        |                    |
| `g_attenuation`      | `Vec3`         |                    |
| `g_dispersion`       | `Float`        |                    |
| `g_thickness`        | `Float`        |                    |
| `g_unlit`            |                |                    |
| `g_double_sided`     |                |                    |
| `va_position`        | `Res<[Vec3]>`  |                    |
| `va_normal`          | `Res<[Vec3]>`  |                    |
| `va_texcoord`        | `Res<[Vec2]>`  |                    |
| `va_roughness`       | `Res<[Float]>` |                    |
| `va_metallic`        | `Res<[Float]>` |                    |
| `va_albedo`          | `Res<[Vec3]>`  |                    |
| `va_alpha`           | `Res<[Float]>` |                    |
| `va_transmission`    | `Res<[Float]>` |                    |
| `va_emission`        | `Res<[Vec3]>`  |                    |
| `tex_normal`         | `Res<Texture>` | Use color channels |
| `tex_roughness`      | `Res<Texture>` | Use green channel  |
| `tex_metallic`       | `Res<Texture>` | Use blue channel   |
| `tex_albedo`         | `Res<Texture>` | Use color channels |
| `tex_alpha`          | `Res<Texture>` | Use alpha channel  |
| `tex_transmission`   | `Res<Texture>` | Use red channel    |
| `tex_emission`       | `Res<Texture>` | Use color channels |
| `tex_thickness`      | `Res<Texture>` | Use green channel  |
| `tex_occlusion`      | `Res<Texture>` | Use red channel    |

- **Attenuation**: Attenuation coefficient for each color channel due to
  scattering within the material volume expressed as e-folding distance (m^-1).
  See [KHR_materials_volume].
- **Transmission**: Equivalent to `transmissionFactor` and `transmissionTexture`
  of [KHR_materials_transmission].
- **Refractive Index**: Equivalent to `ior` of [KHR_materials_ior]
- **Thickness**: Equivalent to `thicknessFactor` and `thicknessTexture` of
  [KHR_materials_volume].
- **Dispersion**: 20 / Abbe Number. Equivalent to `dispersion` of
  [KHR_materials_dispersion].
- **Unlit**: Directly transfers \*_albedo to the screen if set. No lighting
  shaders are applied. See [KHR_materials_unlit]
- **Double Sided**: Disable backface culling for this mesh. Equivalent to
  `material.doubleSided` of glTF 2.0.

## LightPart

| Key        | Value Type               |
| ---------- | ------------------------ |
| `radius`   | `Float`                  |
| `emission` | `Vec3`                   |
| `spot`     | `Vec3`, `Float`, `Float` |

- **Emission**: Luminous intensity in candela per channel. Equivalent of `color`
  multiplied with `intensity` of [KHR_lights_punctual].
- **Radius**: Radius for soft shadow calculation. If set, the light source can
  be modelled to be a light emitting sphere of that radius. Not suported by
  glTF.
- **Spot**: Normalized direction vector, inner and outer cone radius like
  `innerConeAngle` and `outerConeAngle` in [KHR_lights_punctual].

## EnvironmentPart

| Key      | Value Type     |                  |
| -------- | -------------- | ---------------- |
| `skybox` | `Res`          |                  |
| `sun`    | `Vec3`, `Vec3` | Direction, Color |

## Texture

WebP

## CollisionPart

Only one key for shape should be set.

| Key                 | Value Type                |                            |
| ------------------- | ------------------------- | -------------------------- |
| `restitution_coeff` | `Float`                   |                            |
| `friction_kinetic`  | `Float`                   | Coeffient                  |
| `friction_static`   | `Float`                   | Coeffient                  |
| `sh_box`            | `Vec3`                    | Side lengths               |
| `sh_sphere`         | `Float`                   | Radius                     |
| `sh_cylinder`       | `Float`, `Float`, `Float` | Bottom/Top Radius, Height  |
| `sh_capsule`        | `Float`, `Float`, `Float` | Bottom/Top Radius, Height  |
| `sh_convex_hull`    | `Res<[Vec3]>`             | Convex hull points         |
| `sh_mesh`           | `Res<u32>`, `Res<[Vec3]>` | Mesh index + vertex buffer |

[KHR_materials_transmission]: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_transmission
[KHR_materials_ior]: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_ior
[KHR_materials_volume]: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_volume
[KHR_materials_dispersion]: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_dispersion
[KHR_lights_punctual]: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_lights_punctual
[KHR_lights_unlit]: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_lights_unlit