1#import bevy_pbr::utils::rand_f
2
3struct InstanceData {
4    pos_and_scale: vec4<f32>,
5    index: u32,
6    pad1: u32,
7    pad2: u32,
8    pad3: u32,
9}
10
11struct DrawIndexedIndirectArgs {
12    index_count: u32,
13    instance_count: atomic<u32>,
14    first_index: u32,
15    base_vertex: i32,
16    first_instance: u32,
17}
18
19struct CameraCullData {
20    view_pos: vec4<f32>,
21}
22
23struct LodCullData {
24    visibility_range: vec4<f32>,
25    world_from_local: mat4x4<f32>,
26}
27
28@group(0) @binding(0) var<storage, read> source_buffer: array<InstanceData>;
29@group(0) @binding(1) var<storage, read_write> instance_buffer: array<InstanceData>;
30@group(0) @binding(2) var<storage, read_write> indirect_args: DrawIndexedIndirectArgs;
31@group(0) @binding(3) var<uniform> camera: CameraCullData;
32@group(0) @binding(4) var<uniform> lod_data: LodCullData;
33
34
35fn hash_noise(index: u32) -> f32 {
36    var state = index;
37    return rand_f(&state);
38}
39
40@compute @workgroup_size(64)
41fn main(@builtin(global_invocation_id) global_id: vec3<u32>) {
42    let i = global_id.x;
43    if (i >= arrayLength(&source_buffer)) { return; }
44
45    let instance = source_buffer[i];
46    let local_pos = vec4<f32>(instance.pos_and_scale.xyz, 1.0);
47    let world_pos = lod_data.world_from_local * local_pos;
48
49    let dist = distance(world_pos.xyz, camera.view_pos.xyz);
50
51    if (dist < lod_data.visibility_range.x || dist > lod_data.visibility_range.w) {
52        return;
53    }
54
55    let write_index = atomicAdd(&indirect_args.instance_count, 1u);
56
57    instance_buffer[write_index] = instance;
58}