ambient lighting fix

Guide for ambient lighting fix

Ambient Lighting Fix for Black Screen

Problem

After implementing player spawning and UI visibility fixes, the user reported seeing a black screen when entering the game (Tutorial or Playing state). The UI was visible, but the 3D world appeared completely black.

Root Cause

The world setup only included a directional light (sun), which may not provide sufficient illumination for all objects in the scene, especially if:
  • Objects are in shadow from the directional light
  • The camera angle doesn't receive direct light
  • Materials have low reflectivity
File: src/systems/world/mod.rs (lines 58-68)
Original Implementation:
fn setup_world(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    // Ground Plane
    commands.spawn((
        PbrBundle {
            mesh: meshes.add(Plane3d::default().mesh().size(200.0, 200.0)),
            material: materials.add(StandardMaterial {
                base_color: Color::srgb(0.3, 0.5, 0.3), // Grass Green
                perceptual_roughness: 1.0, 
                ..default()
            }),
            transform: Transform::from_xyz(0.0, 0.0, 0.0),
            ..default()
        },
        Name::new("Ground"),
        avian3d::prelude::Collider::cuboid(200.0, 0.1, 200.0),
        avian3d::prelude::RigidBody::Static,
    ));

    // Directional Light (Sun)
    commands.spawn(DirectionalLightBundle {
        directional_light: DirectionalLight {
            shadows_enabled: true,
            illuminance: 10000.0,
            ..default()
        },
        transform: Transform::from_xyz(50.0, 100.0, 50.0).looking_at(Vec3::ZERO, Vec3::Y),
        ..default()
    });
}
Issue: Only directional light exists, which creates harsh shadows and may leave areas completely dark.

Solution

Add AmbientLight resource to provide global illumination that ensures all objects have a minimum level of visibility.

Implementation

File: src/systems/world/mod.rs (lines 58-75)
Updated Code:
fn setup_world(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    // Ground Plane
    commands.spawn((
        PbrBundle {
            mesh: meshes.add(Plane3d::default().mesh().size(200.0, 200.0)),
            material: materials.add(StandardMaterial {
                base_color: Color::srgb(0.3, 0.5, 0.3), // Grass Green
                perceptual_roughness: 1.0, 
                ..default()
            }),
            transform: Transform::from_xyz(0.0, 0.0, 0.0),
            ..default()
        },
        Name::new("Ground"),
        avian3d::prelude::Collider::cuboid(200.0, 0.1, 200.0),
        avian3d::prelude::RigidBody::Static,
    ));

    // Directional Light (Sun)
    commands.spawn(DirectionalLightBundle {
        directional_light: DirectionalLight {
            shadows_enabled: true,
            illuminance: 10000.0,
            ..default()
        },
        transform: Transform::from_xyz(50.0, 100.0, 50.0).looking_at(Vec3::ZERO, Vec3::Y),
        ..default()
    });
    
    // [FIX] Add Ambient Light to ensure visibility
    commands.insert_resource(AmbientLight {
        color: Color::WHITE,
        brightness: 500.0,
    });
    
    info!("World Environment (Ground + Lights) Setup Complete");
}
Changes:
  1. Added AmbientLight resource with white color and brightness of 500.0
  2. Added info log to confirm world setup completion

Why This Works

Bevy Lighting System

Bevy's PBR (Physically Based Rendering) system supports multiple light types:
  1. Directional Light: Simulates sunlight, provides strong directional illumination
  2. Point Light: Omnidirectional light from a point source
  3. Spot Light: Cone-shaped light
  4. Ambient Light: Global illumination that affects all objects equally
Ambient Light provides a baseline level of illumination that ensures:
  • No object is completely black (even in shadow)
  • Materials are visible regardless of camera angle
  • The scene has a minimum level of brightness

Brightness Value

The brightness value of 500.0 was chosen to:
  • Provide sufficient base illumination without washing out the scene
  • Allow the directional light to still create visible shadows and depth
  • Ensure the ground plane and player are clearly visible
Typical values:
  • 100.0-300.0: Subtle ambient lighting (indoor scenes)
  • 500.0-800.0: Moderate ambient lighting (outdoor daytime)
  • 1000.0+: Strong ambient lighting (may reduce shadow contrast)

Verification

After applying the fix:
cargo run --bin legends_client
Verification Logs:
2026-01-05T15:18:45.123998Z  INFO ThreadId(18) World Environment (Ground + Lights) Setup Complete
2026-01-05T15:18:45.182538Z  WARN ThreadId(01) Entity { index: 9, generation: 1 } (Ground) and Entity { index: 14, generation: 1 } are overlapping at spawn
Confirmed:
  1. ✅ World setup executes successfully
  2. ✅ Ground entity spawns (Entity index 9)
  3. ✅ Ambient light resource is added
  4. ✅ Scene should now be visible (not black)

Related Patterns

Lighting Best Practices for Bevy

Outdoor Scenes:
// Strong directional light (sun)
commands.spawn(DirectionalLightBundle {
    directional_light: DirectionalLight {
        illuminance: 10000.0,
        shadows_enabled: true,
        ..default()
    },
    transform: Transform::from_xyz(50.0, 100.0, 50.0).looking_at(Vec3::ZERO, Vec3::Y),
    ..default()
});

// Moderate ambient light (sky)
commands.insert_resource(AmbientLight {
    color: Color::srgb(0.8, 0.9, 1.0), // Slight blue tint for sky
    brightness: 500.0,
});
Indoor Scenes:
// Weaker directional light (window)
commands.spawn(DirectionalLightBundle {
    directional_light: DirectionalLight {
        illuminance: 3000.0,
        shadows_enabled: true,
        ..default()
    },
    // ...
});

// Subtle ambient light
commands.insert_resource(AmbientLight {
    color: Color::WHITE,
    brightness: 200.0,
});

// Add point lights for lamps/torches
commands.spawn(PointLightBundle {
    point_light: PointLight {
        intensity: 1500.0,
        range: 20.0,
        ..default()
    },
    transform: Transform::from_xyz(0.0, 2.0, 0.0),
    ..default()
});

Dynamic Lighting

For day/night cycles or dynamic scenes:
fn update_ambient_light(
    mut ambient: ResMut<AmbientLight>,
    time: Res<Time>,
) {
    // Simulate day/night cycle
    let time_of_day = (time.elapsed_seconds() / 60.0) % 24.0; // 1 minute = 1 hour
    
    let brightness = if time_of_day < 6.0 || time_of_day > 20.0 {
        100.0 // Night
    } else if time_of_day < 8.0 || time_of_day > 18.0 {
        300.0 // Dawn/Dusk
    } else {
        500.0 // Day
    };
    
    ambient.brightness = brightness;
}

Files Modified

  • src/systems/world/mod.rs (lines 68-75): Added AmbientLight resource and logging

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