SpotLight / PointLight artifacts in FogVolume

[TimiSillman]

Bevy version

0.15.3

[Optional] Relevant system information

AdapterInfo { name: "NVIDIA GeForce RTX 3060 Ti", vendor: 4318, device: 9353, device_type: DiscreteGpu, driver: "NVIDIA", driver_info: "570.124.04", backend: Vulkan }

What you did

use bevy::{
    color::palettes::css::RED,
    core_pipeline::{bloom::Bloom, tonemapping::Tonemapping},
    pbr::{FogVolume, VolumetricFog, VolumetricLight},
    prelude::*,
};

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, setup)
        .add_systems(Update, move_camera)
        .run();
}

fn setup(mut commands: Commands) {
    commands.spawn((
        Transform::from_xyz(-2., 0., 0.),
        SpotLight {
            intensity: 5000.0, // lumens
            color: RED.into(),
            shadows_enabled: true,
            ..default()
        },
        VolumetricLight,
    ));

    commands.spawn((
        Transform::from_xyz(2., 0., 0.),
        SpotLight {
            intensity: 5000.0, // lumens
            color: RED.into(),
            shadows_enabled: true,
            ..default()
        },
        VolumetricLight,
    ));

    commands.spawn((
        FogVolume::default(),
        Transform::from_scale(Vec3::splat(35.0)),
    ));

    commands.spawn((
        Camera3d::default(),
        Camera {
            hdr: true,
            ..default()
        },
        Transform::from_xyz(0., 0., 5.),
        Tonemapping::TonyMcMapface,
        Bloom::default(),
        VolumetricFog {
            ambient_intensity: 0.,
            ..default()
        },
    ));
}

fn move_camera(
    mut query: Query<&mut Transform, With<Camera3d>>,
    input: Res<ButtonInput<KeyCode>>,
    time: Res<Time>,
) {
    for mut transform in query.iter_mut() {
        if input.pressed(KeyCode::ArrowUp) {
            transform.translation.z -= 10. * time.delta_secs();
        }

        if input.pressed(KeyCode::ArrowDown) {
            transform.translation.z += 10. * time.delta_secs();
        }

        if input.pressed(KeyCode::KeyZ) {
            transform.translation.z = 5.;
        }

        if input.pressed(KeyCode::KeyX) {
            transform.translation.z = 130.;
        }
    }
}

What went wrong

Using SpotLights or PointLights creates weird artifacts and is not always rendered. See video below

Additional information

First half of the video shows camera at z position 5. and creates weird artifacts. In second half of the video camera is positioned at z 130. lights are rendered and when moving camera back or forward lights disappear.

untitled.mp4

[eero-lehtinen]

I had the exact same issue when testing out fog volumes in a large scene. It just wasn't usable at all. (Windows 11, 3070 TI)

[mate-h]

I've done some initial triage and it seems that the reason those artifacts appear is because the light clusters in the center of the screen in this example don't get rendered. These lines are to blame:

https://github.com/bevyengine/bevy/blob/main/crates/bevy_pbr/src/volumetric_fog/volumetric_fog.wgsl#L312-L315

Further investigation is needed why those light clusters that are in the viewport are not in the marked as in range to do the raymarch for.