1#import bevy_pbr::{
2    atmosphere::{
3        bindings::settings,
4        functions::{
5            get_view_position, raymarch_atmosphere,
6            max_atmosphere_distance, direction_atmosphere_to_world,
7            sky_view_lut_uv_to_zenith_azimuth, zenith_azimuth_to_ray_dir,
8        },
9    }
10}
11
12#import bevy_render::{
13    view::View,
14    maths::HALF_PI,
15}
16#import bevy_core_pipeline::fullscreen_vertex_shader::FullscreenVertexOutput
17
18@group(0) @binding(13) var sky_view_lut_out: texture_storage_2d<rgba16float, write>;
19
20@compute
21@workgroup_size(16, 16, 1)
22fn main(@builtin(global_invocation_id) idx: vec3<u32>) {
23    let uv = vec2<f32>(idx.xy) / vec2<f32>(settings.sky_view_lut_size);
24
25    let cam_pos = get_view_position();
26    let r = length(cam_pos);
27    var zenith_azimuth = sky_view_lut_uv_to_zenith_azimuth(r, uv);
28
29    let ray_dir_as = zenith_azimuth_to_ray_dir(zenith_azimuth.x, zenith_azimuth.y);
30    let ray_dir_ws = direction_atmosphere_to_world(ray_dir_as);
31
32    let world_pos = vec3(0.0, r, 0.0);
33    let up = normalize(world_pos);
34    let mu = dot(ray_dir_ws, up);
35    let t_max = max_atmosphere_distance(r, mu);
36
37    let result = raymarch_atmosphere(world_pos, ray_dir_ws, t_max, settings.sky_view_lut_samples, uv, true);
38
39    textureStore(sky_view_lut_out, idx.xy, vec4(result.inscattering, 1.0));
40}