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Compute light attenuation using Beer's law #24516

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Compute light attenuation using Beer's law #24516

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91894fe
Fix volume attenuation
Jun 2, 2026
40b7d44
Compute light attenuation using Beer's law
Jun 3, 2026
f86879e
Load glTF thickness textures as linear
Jun 3, 2026
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7 changes: 7 additions & 0 deletions crates/bevy_gltf/src/loader/gltf_ext/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,13 @@ pub(crate) fn get_linear_textures(document: &Document) -> HashSet<usize> {
{
linear_textures.insert(texture_index);
}
#[cfg(feature = "pbr_transmission_textures")]
if let Some(texture) = material
.volume()
.and_then(|volume| volume.thickness_texture())
{
linear_textures.insert(texture.texture().index());
}

// None of the clearcoat maps should be loaded as sRGB.
#[cfg(feature = "pbr_multi_layer_material_textures")]
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21 changes: 8 additions & 13 deletions crates/bevy_pbr/src/render/pbr_functions.wgsl
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Original file line number Diff line number Diff line change
Expand Up @@ -851,19 +851,14 @@ fn apply_pbr_lighting(
#ifdef STANDARD_MATERIAL_SPECULAR_TRANSMISSION
transmitted_light += transmission::specular_transmissive_light(in.world_position, in.frag_coord.xyz, view_z, in.N, in.V, F0, ior, thickness, perceptual_roughness, specular_transmissive_color, specular_transmitted_environment_light).rgb;

if (in.material.flags & pbr_types::STANDARD_MATERIAL_FLAGS_ATTENUATION_ENABLED_BIT) != 0u {
// We reuse the `atmospheric_fog()` function here, as it's fundamentally
// equivalent to the attenuation that takes place inside the material volume,
// and will allow us to eventually hook up subsurface scattering more easily
var attenuation_fog: mesh_view_types::Fog;
attenuation_fog.base_color.a = 1.0;
attenuation_fog.be = pow(1.0 - in.material.attenuation_color.rgb, vec3<f32>(E)) / in.material.attenuation_distance;
// TODO: Add the subsurface scattering factor below
// attenuation_fog.bi = /* ... */
transmitted_light = bevy_pbr::fog::atmospheric_fog(
attenuation_fog, vec4<f32>(transmitted_light, 1.0), thickness,
vec3<f32>(0.0) // TODO: Pass in (pre-attenuated) scattered light contribution here
).rgb;
if (in.material.flags & pbr_types::STANDARD_MATERIAL_FLAGS_ATTENUATION_ENABLED_BIT) != 0u
&& in.material.attenuation_distance != 0.0 {
// Compute light attenuation using Beer's law.
let transmittance = pow(
in.material.attenuation_color.rgb,
vec3<f32>(thickness / in.material.attenuation_distance),
);
transmitted_light *= transmittance;
}
#endif

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