bevy/examples/ecs/parallel_query.rs
Carter Anderson 11b41206eb Add upstream bevy_ecs and prepare for custom-shaders merge (#2815)
This updates the `pipelined-rendering` branch to use the latest `bevy_ecs` from `main`. This accomplishes a couple of goals:

1. prepares for upcoming `custom-shaders` branch changes, which were what drove many of the recent bevy_ecs changes on `main`
2. prepares for the soon-to-happen merge of `pipelined-rendering` into `main`. By including bevy_ecs changes now, we make that merge simpler / easier to review. 

I split this up into 3 commits:

1. **add upstream bevy_ecs**: please don't bother reviewing this content. it has already received thorough review on `main` and is a literal copy/paste of the relevant folders (the old folders were deleted so the directories are literally exactly the same as `main`).
2. **support manual buffer application in stages**: this is used to enable the Extract step. we've already reviewed this once on the `pipelined-rendering` branch, but its worth looking at one more time in the new context of (1).
3. **support manual archetype updates in QueryState**: same situation as (2).
2021-09-14 06:14:19 +00:00

78 lines
2.7 KiB
Rust

use bevy::{prelude::*, tasks::prelude::*};
use rand::random;
struct Velocity(Vec2);
fn spawn_system(
mut commands: Commands,
asset_server: Res<AssetServer>,
mut materials: ResMut<Assets<ColorMaterial>>,
) {
commands.spawn_bundle(OrthographicCameraBundle::new_2d());
let texture_handle = asset_server.load("branding/icon.png");
let material = materials.add(texture_handle.into());
for _ in 0..128 {
commands
.spawn_bundle(SpriteBundle {
material: material.clone(),
transform: Transform::from_scale(Vec3::splat(0.1)),
..Default::default()
})
.insert(Velocity(
20.0 * Vec2::new(random::<f32>() - 0.5, random::<f32>() - 0.5),
));
}
}
// Move sprites according to their velocity
fn move_system(pool: Res<ComputeTaskPool>, mut sprites: Query<(&mut Transform, &Velocity)>) {
// Compute the new location of each sprite in parallel on the
// ComputeTaskPool using batches of 32 sprites
//
// 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_for_each_mut(&pool, 32, |(mut transform, velocity)| {
transform.translation += velocity.0.extend(0.0);
});
}
// Bounce sprites outside the window
fn bounce_system(
pool: Res<ComputeTaskPool>,
windows: Res<Windows>,
mut sprites: Query<(&Transform, &mut Velocity)>,
) {
let window = windows.get_primary().expect("No primary window.");
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;
sprites
// Batch size of 32 is chosen to limit the overhead of
// ParallelIterator, since negating a vector is very inexpensive.
.par_for_each_mut(&pool, 32, |(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_startup_system(spawn_system)
.add_system(move_system)
.add_system(bounce_system)
.run();
}