1#define_import_path bevy_pbr::skinning
2
3#import bevy_pbr::mesh_types::SkinnedMesh
4#import bevy_pbr::mesh_bindings::mesh
5
6#ifdef SKINNED
7
8#ifdef SKINS_USE_UNIFORM_BUFFERS
9@group(2) @binding(1) var<uniform> joint_matrices: SkinnedMesh;
10#else   // SKINS_USE_UNIFORM_BUFFERS
11@group(2) @binding(1) var<storage> joint_matrices: array<mat4x4<f32>>;
12#endif  // SKINS_USE_UNIFORM_BUFFERS
13
14// An array of matrices specifying the joint positions from the previous frame.
15//
16// This is used for motion vector computation.
17//
18// If this is the first frame, or we're otherwise prevented from using data from
19// the previous frame, this is simply the same as `joint_matrices` above.
20#ifdef SKINS_USE_UNIFORM_BUFFERS
21@group(2) @binding(6) var<uniform> prev_joint_matrices: SkinnedMesh;
22#else   // SKINS_USE_UNIFORM_BUFFERS
23@group(2) @binding(6) var<storage> prev_joint_matrices: array<mat4x4<f32>>;
24#endif  // SKINS_USE_UNIFORM_BUFFERS
25
26fn skin_model(
27    indexes: vec4<u32>,
28    weights: vec4<f32>,
29    instance_index: u32,
30) -> mat4x4<f32> {
31#ifdef SKINS_USE_UNIFORM_BUFFERS
32    return weights.x * joint_matrices.data[indexes.x]
33        + weights.y * joint_matrices.data[indexes.y]
34        + weights.z * joint_matrices.data[indexes.z]
35        + weights.w * joint_matrices.data[indexes.w];
36#else   // SKINS_USE_UNIFORM_BUFFERS
37    var skin_index = mesh[instance_index].current_skin_index;
38    return weights.x * joint_matrices[skin_index + indexes.x]
39        + weights.y * joint_matrices[skin_index + indexes.y]
40        + weights.z * joint_matrices[skin_index + indexes.z]
41        + weights.w * joint_matrices[skin_index + indexes.w];
42#endif  // SKINS_USE_UNIFORM_BUFFERS
43}
44
45// Returns the skinned position of a vertex with the given weights from the
46// previous frame.
47//
48// This is used for motion vector computation.
49fn skin_prev_model(
50    indexes: vec4<u32>,
51    weights: vec4<f32>,
52    instance_index: u32,
53) -> mat4x4<f32> {
54#ifdef SKINS_USE_UNIFORM_BUFFERS
55    return weights.x * prev_joint_matrices.data[indexes.x]
56        + weights.y * prev_joint_matrices.data[indexes.y]
57        + weights.z * prev_joint_matrices.data[indexes.z]
58        + weights.w * prev_joint_matrices.data[indexes.w];
59#else   // SKINS_USE_UNIFORM_BUFFERS
60    let skin_index = mesh[instance_index].current_skin_index;
61    return weights.x * prev_joint_matrices[skin_index + indexes.x]
62        + weights.y * prev_joint_matrices[skin_index + indexes.y]
63        + weights.z * prev_joint_matrices[skin_index + indexes.z]
64        + weights.w * prev_joint_matrices[skin_index + indexes.w];
65#endif  // SKINS_USE_UNIFORM_BUFFERS
66}
67
68fn inverse_transpose_3x3m(in: mat3x3<f32>) -> mat3x3<f32> {
69    let x = cross(in[1], in[2]);
70    let y = cross(in[2], in[0]);
71    let z = cross(in[0], in[1]);
72    let det = dot(in[2], z);
73    return mat3x3<f32>(
74        x / det,
75        y / det,
76        z / det
77    );
78}
79
80fn skin_normals(
81    world_from_local: mat4x4<f32>,
82    normal: vec3<f32>,
83) -> vec3<f32> {
84    return normalize(
85        inverse_transpose_3x3m(
86            mat3x3<f32>(
87                world_from_local[0].xyz,
88                world_from_local[1].xyz,
89                world_from_local[2].xyz
90            )
91        ) * normal
92    );
93}
94
95#endif