06bf928927
# Objective Issue #10243: rendering multiple triangles in the same place results in flickering. ## Solution Considered these alternatives: - `depth_bias` may not work, because of high number of entities, so creating a material per entity is practically not possible - rendering at slightly different positions does not work, because when camera is far, float rounding causes the same issues (edit: assuming we have to use the same `depth_bias`) - considered implementing deterministic operation like `query.par_iter().flat_map(...).collect()` to be used in `check_visibility` system (which would solve the issue since query is deterministic), and could not figure out how to make it as cheap as current approach with thread-local collectors (#11249) So adding an option to sort entities after `check_visibility` system run. Should not be too bad, because after visibility check, only a handful entities remain. This is probably not the only source of non-determinism in Bevy, but this is one I could find so far. At least it fixes the repro example. ## Changelog - `DeterministicRenderingConfig` option to enable deterministic rendering ## Test <img width="1392" alt="image" src="https://github.com/bevyengine/bevy/assets/28969/c735bce1-3a71-44cd-8677-c19f6c0ee6bd"> --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
88 lines
2.8 KiB
Rust
88 lines
2.8 KiB
Rust
//! Shows how to enable deterministic rendering which helps with flickering due to z-fighting.
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//! Rendering is not deterministic by default.
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//! Note most users don't need rendering to be deterministic, and should rely on depth bias instead.
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use bevy::app::App;
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use bevy::app::Startup;
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use bevy::prelude::shape::Plane;
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use bevy::prelude::*;
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use bevy::render::deterministic::DeterministicRenderingConfig;
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.add_systems(Startup, setup)
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.add_systems(Update, (keys, update_help).chain())
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.run();
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}
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fn setup(
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mut commands: Commands,
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mut materials: ResMut<Assets<StandardMaterial>>,
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mut meshes: ResMut<Assets<Mesh>>,
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mut deterministic_rendering_config: ResMut<DeterministicRenderingConfig>,
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) {
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// Safe default.
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deterministic_rendering_config.stable_sort_z_fighting = true;
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// Help message will be rendered there.
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commands.spawn(TextBundle::default());
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commands.spawn(Camera3dBundle {
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transform: Transform::from_xyz(3.0, 3.0, 3.0).looking_at(Vec3::new(0., 0., 0.), Vec3::Y),
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..default()
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});
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let mesh = meshes.add(Plane::from_size(2.0));
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for i in 0..360 {
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let color = Color::hsl(i as f32, 1.0, 0.5);
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commands.spawn(PbrBundle {
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mesh: mesh.clone(),
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material: materials.add(StandardMaterial {
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base_color: color,
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// Setting depth bias would be a default choice to fix z-fighting.
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// When it is not possible, deterministic rendering can be used.
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// Here we intentionally don't use depth bias to demonstrate the issue.
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depth_bias: 0.0,
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unlit: true,
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..Default::default()
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}),
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..default()
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});
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}
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}
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fn keys(
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mut deterministic_rendering_config: ResMut<DeterministicRenderingConfig>,
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keyboard_input: Res<ButtonInput<KeyCode>>,
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) {
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if keyboard_input.just_pressed(KeyCode::KeyD) {
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deterministic_rendering_config.stable_sort_z_fighting ^= true;
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}
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}
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fn update_help(
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mut text: Query<&mut Text>,
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deterministic_rendering_config: Res<DeterministicRenderingConfig>,
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) {
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if deterministic_rendering_config.is_changed() {
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*text.single_mut() = Text::from_section(
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format!(
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"\
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Press D to enable/disable deterministic rendering\n\
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\n\
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Deterministic rendering: {}\n\
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\n\
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When rendering is not deterministic, you may notice flickering due to z-fighting\n\
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\n\
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Warning: may cause seizures for people with photosensitive epilepsy",
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deterministic_rendering_config.stable_sort_z_fighting
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),
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TextStyle {
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font_size: 20.,
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..default()
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},
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);
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}
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}
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