1enable dual_source_blending;
2
3#import bevy_pbr::atmosphere::{
4    types::{Atmosphere, AtmosphereSettings},
5    bindings::{atmosphere, view, atmosphere_transforms, settings},
6    functions::{
7        sample_transmittance_lut, sample_transmittance_lut_segment,
8        sample_sky_view_lut, direction_world_to_atmosphere,
9        uv_to_ray_direction, uv_to_ndc, sample_aerial_view_lut,
10        sample_sun_radiance, ndc_to_camera_dist, raymarch_atmosphere, 
11        get_view_position, max_atmosphere_distance
12    },
13};
14#import bevy_render::view::View;
15
16#import bevy_core_pipeline::fullscreen_vertex_shader::FullscreenVertexOutput
17
18#ifdef MULTISAMPLED
19@group(0) @binding(13) var depth_texture: texture_depth_multisampled_2d;
20#else
21@group(0) @binding(13) var depth_texture: texture_depth_2d;
22#endif
23
24struct RenderSkyOutput {
25#ifdef DUAL_SOURCE_BLENDING
26    @location(0) @blend_src(0) inscattering: vec4<f32>,
27    @location(0) @blend_src(1) transmittance: vec4<f32>,
28#else
29    @location(0) inscattering: vec4<f32>,
30#endif
31}
32
33@fragment
34fn main(in: FullscreenVertexOutput) -> RenderSkyOutput {
35    let depth = textureLoad(depth_texture, vec2<i32>(in.position.xy), 0);
36
37    let ray_dir_ws = uv_to_ray_direction(in.uv);
38    let world_pos = get_view_position();
39    let r = length(world_pos);
40    let up = normalize(world_pos);
41    let mu = dot(ray_dir_ws, up);
42    let max_samples = settings.sky_max_samples;
43    let should_raymarch = settings.rendering_method == 1u;
44
45    var transmittance: vec3<f32>;
46    var inscattering: vec3<f32>;
47
48    let sun_radiance = sample_sun_radiance(ray_dir_ws);
49
50    if depth == 0.0 {
51        let ray_dir_as = direction_world_to_atmosphere(ray_dir_ws, up);
52        transmittance = sample_transmittance_lut(r, mu);
53        inscattering = sample_sky_view_lut(r, ray_dir_as);
54        if should_raymarch {
55            let t_max = max_atmosphere_distance(r, mu);
56            let result = raymarch_atmosphere(world_pos, ray_dir_ws, t_max, max_samples, in.uv, true);
57            inscattering = result.inscattering;
58            transmittance = result.transmittance;
59        }
60        inscattering += sun_radiance * transmittance;
61    } else {
62        let t = ndc_to_camera_dist(vec3(uv_to_ndc(in.uv), depth));
63        inscattering = sample_aerial_view_lut(in.uv, t);
64        transmittance = sample_transmittance_lut_segment(r, mu, t);
65        if should_raymarch {
66            let result = raymarch_atmosphere(world_pos, ray_dir_ws, t, max_samples, in.uv, false);
67            inscattering = result.inscattering;
68            transmittance = result.transmittance;
69        }
70    }
71
72    // exposure compensation
73    inscattering *= view.exposure;
74    
75#ifdef DUAL_SOURCE_BLENDING
76    return RenderSkyOutput(vec4(inscattering, 0.0), vec4(transmittance, 1.0));
77#else
78    let mean_transmittance = (transmittance.r + transmittance.g + transmittance.b) / 3.0;
79    return RenderSkyOutput(vec4(inscattering, mean_transmittance));
80#endif
81    
82}