# Objective
- Some examples crash in CI because of needing too many resources for
the windows runner
- Some examples have random results making it hard to compare
screenshots
## Solution
- `bloom_3d`: reduce the number of spheres
- `pbr`:  use simpler spheres and reuse the mesh
- `tonemapping`: use simpler spheres and reuse the mesh
- `shadow_biases`: reduce the number of spheres
- `spotlight`: use a seeded rng, move more cubes in view while reducing
the total number of cubes, and reuse meshes and materials
- `external_source_external_thread`, `iter_combinations`,
`parallel_query`: use a seeded rng
Examples of errors encountered:
```
Caused by:
    In Device::create_bind_group
      note: label = `bloom_upsampling_bind_group`
    Not enough memory left
```
```
Caused by:
    In Queue::write_buffer
    Parent device is lost
```
```
ERROR wgpu_core::device::life: Mapping failed Device(Lost)
```
		
	
			
		
			
				
	
	
		
			77 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
			
		
		
	
	
			77 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
//! Illustrates parallel queries with `ParallelIterator`.
 | 
						|
 | 
						|
use bevy::ecs::query::BatchingStrategy;
 | 
						|
use bevy::prelude::*;
 | 
						|
use rand::{rngs::StdRng, Rng, SeedableRng};
 | 
						|
 | 
						|
#[derive(Component, Deref)]
 | 
						|
struct Velocity(Vec2);
 | 
						|
 | 
						|
fn spawn_system(mut commands: Commands, asset_server: Res<AssetServer>) {
 | 
						|
    commands.spawn(Camera2dBundle::default());
 | 
						|
    let texture = asset_server.load("branding/icon.png");
 | 
						|
    let mut rng = StdRng::seed_from_u64(19878367467713);
 | 
						|
    for _ in 0..128 {
 | 
						|
        commands.spawn((
 | 
						|
            SpriteBundle {
 | 
						|
                texture: texture.clone(),
 | 
						|
                transform: Transform::from_scale(Vec3::splat(0.1)),
 | 
						|
                ..default()
 | 
						|
            },
 | 
						|
            Velocity(20.0 * Vec2::new(rng.gen::<f32>() - 0.5, rng.gen::<f32>() - 0.5)),
 | 
						|
        ));
 | 
						|
    }
 | 
						|
}
 | 
						|
 | 
						|
// Move sprites according to their velocity
 | 
						|
fn move_system(mut sprites: Query<(&mut Transform, &Velocity)>) {
 | 
						|
    // Compute the new location of each sprite in parallel on the
 | 
						|
    // ComputeTaskPool
 | 
						|
    //
 | 
						|
    // This example is only for demonstrative purposes. Using a
 | 
						|
    // ParallelIterator for an inexpensive operation like addition on only 128
 | 
						|
    // elements will not typically be faster than just using a normal Iterator.
 | 
						|
    // See the ParallelIterator documentation for more information on when
 | 
						|
    // to use or not use ParallelIterator over a normal Iterator.
 | 
						|
    sprites
 | 
						|
        .par_iter_mut()
 | 
						|
        .for_each(|(mut transform, velocity)| {
 | 
						|
            transform.translation += velocity.extend(0.0);
 | 
						|
        });
 | 
						|
}
 | 
						|
 | 
						|
// Bounce sprites outside the window
 | 
						|
fn bounce_system(windows: Query<&Window>, mut sprites: Query<(&Transform, &mut Velocity)>) {
 | 
						|
    let window = windows.single();
 | 
						|
    let width = window.width();
 | 
						|
    let height = window.height();
 | 
						|
    let left = width / -2.0;
 | 
						|
    let right = width / 2.0;
 | 
						|
    let bottom = height / -2.0;
 | 
						|
    let top = height / 2.0;
 | 
						|
    // The default batch size can also be overridden.
 | 
						|
    // In this case a batch size of 32 is chosen to limit the overhead of
 | 
						|
    // ParallelIterator, since negating a vector is very inexpensive.
 | 
						|
    sprites
 | 
						|
        .par_iter_mut()
 | 
						|
        .batching_strategy(BatchingStrategy::fixed(32))
 | 
						|
        .for_each(|(transform, mut v)| {
 | 
						|
            if !(left < transform.translation.x
 | 
						|
                && transform.translation.x < right
 | 
						|
                && bottom < transform.translation.y
 | 
						|
                && transform.translation.y < top)
 | 
						|
            {
 | 
						|
                // For simplicity, just reverse the velocity; don't use realistic bounces
 | 
						|
                v.0 = -v.0;
 | 
						|
            }
 | 
						|
        });
 | 
						|
}
 | 
						|
 | 
						|
fn main() {
 | 
						|
    App::new()
 | 
						|
        .add_plugins(DefaultPlugins)
 | 
						|
        .add_systems(Startup, spawn_system)
 | 
						|
        .add_systems(Update, (move_system, bounce_system))
 | 
						|
        .run();
 | 
						|
}
 |