35f1af522a
# Objective This example uses a seeded RNG for the initial setup, but new unseeded RNGs during each timed update. This is causing the example to produce different output each time in the [example report](https://bevyengine.github.io/bevy-example-runner/). <img width="838" alt="image" src="https://github.com/user-attachments/assets/05d78083-97d0-4bcf-aebc-f645b570d144" /> ## Solution Store and reuse the RNG, following the pattern used in other examples. ## Testing `cargo run --example tilemap_chunk`
82 lines
2.3 KiB
Rust
82 lines
2.3 KiB
Rust
//! Shows a tilemap chunk rendered with a single draw call.
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use bevy::{
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prelude::*,
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sprite::{TilemapChunk, TilemapChunkIndices},
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};
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use rand::{Rng, SeedableRng};
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use rand_chacha::ChaCha8Rng;
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins.set(ImagePlugin::default_nearest()))
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.add_systems(Startup, setup)
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.add_systems(Update, (update_tileset_image, update_tilemap))
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.run();
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}
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#[derive(Component, Deref, DerefMut)]
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struct UpdateTimer(Timer);
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#[derive(Resource, Deref, DerefMut)]
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struct SeededRng(ChaCha8Rng);
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fn setup(mut commands: Commands, assets: Res<AssetServer>) {
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// We're seeding the PRNG here to make this example deterministic for testing purposes.
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// This isn't strictly required in practical use unless you need your app to be deterministic.
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let mut rng = ChaCha8Rng::seed_from_u64(42);
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let chunk_size = UVec2::splat(64);
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let tile_display_size = UVec2::splat(8);
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let indices: Vec<Option<u16>> = (0..chunk_size.element_product())
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.map(|_| rng.gen_range(0..5))
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.map(|i| if i == 0 { None } else { Some(i - 1) })
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.collect();
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commands.spawn((
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TilemapChunk {
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chunk_size,
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tile_display_size,
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tileset: assets.load("textures/array_texture.png"),
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..default()
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},
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TilemapChunkIndices(indices),
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UpdateTimer(Timer::from_seconds(0.1, TimerMode::Repeating)),
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));
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commands.spawn(Camera2d);
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commands.insert_resource(SeededRng(rng));
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}
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fn update_tileset_image(
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chunk_query: Single<&TilemapChunk>,
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mut events: EventReader<AssetEvent<Image>>,
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mut images: ResMut<Assets<Image>>,
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) {
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let chunk = *chunk_query;
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for event in events.read() {
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if event.is_loaded_with_dependencies(chunk.tileset.id()) {
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let image = images.get_mut(&chunk.tileset).unwrap();
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image.reinterpret_stacked_2d_as_array(4);
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}
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}
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}
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fn update_tilemap(
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time: Res<Time>,
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mut query: Query<(&mut TilemapChunkIndices, &mut UpdateTimer)>,
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mut rng: ResMut<SeededRng>,
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) {
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for (mut indices, mut timer) in query.iter_mut() {
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timer.tick(time.delta());
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if timer.just_finished() {
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for _ in 0..50 {
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let index = rng.gen_range(0..indices.len());
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indices[index] = Some(rng.gen_range(0..5));
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}
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}
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}
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}
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