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