Shadow mapping in distance fog

crates/bevy_pbr/src/render/pbr_functions.wgsl

@@ -12,6 +12,7 @@
     shadows,
     ambient,
     irradiance_volume,
+    view_transformations,
     mesh_types::{MESH_FLAGS_SHADOW_RECEIVER_BIT, MESH_FLAGS_TRANSMITTED_SHADOW_RECEIVER_BIT},
 }
 #import bevy_render::maths::{E, powsafe}
@@ -767,19 +768,34 @@ fn apply_fog(fog_params: mesh_view_types::Fog, input_color: vec4<f32>, fragment_
     // fog shape that looks a bit fake
     let distance = length(view_to_world);
 
+    // Calculate view_z for shadow cascade selection
+    let view_pos = view_transformations::position_world_to_view(fragment_world_position);
+    let view_z = view_pos.z;
+
+    // Approximate surface normal using view direction for shadow sampling
+    let view_direction_normal = normalize(-view_to_world);
+    let fragment_world_position_vec4 = vec4<f32>(fragment_world_position, 1.0);
+
     var scattering = vec3<f32>(0.0);
     if fog_params.directional_light_color.a > 0.0 {
         let view_to_world_normalized = view_to_world / distance;
         let n_directional_lights = view_bindings::lights.n_directional_lights;
         for (var i: u32 = 0u; i < n_directional_lights; i = i + 1u) {
-            let light = view_bindings::lights.directional_lights[i];
-            scattering += pow(
+            let light = view_bindings::lights.directional_lights[i];            
+            let scattering_contribution = pow(
                 max(
                     dot(view_to_world_normalized, light.direction_to_light),
                     0.0
                 ),
                 fog_params.directional_light_exponent
             ) * light.color.rgb * view_bindings::view.exposure;
+
+            // Sample shadow map to attenuate inscattering in shadowed areas
+            var shadow: f32 = 1.0;
+            if ((light.flags & mesh_view_types::DIRECTIONAL_LIGHT_FLAGS_SHADOWS_ENABLED_BIT) != 0u) {
+                shadow = shadows::fetch_directional_shadow(i, fragment_world_position_vec4, view_direction_normal, view_z);
+            }
+            scattering += scattering_contribution * shadow;
         }
     }