bevy/examples/2d/mesh2d.rs

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//! Shows how to render a polygonal [`Mesh`], generated from a [`Quad`] primitive, in a 2D scene.
Fix intra-doc link warnings (#10445) When `cargo doc -Zunstable-options -Zrustdoc-scrape-examples` (trying to figure out why it doesn't work with bevy), I had the following warnings: ``` warning: unresolved link to `Quad` --> examples/2d/mesh2d.rs:1:66 | 1 | //! Shows how to render a polygonal [`Mesh`], generated from a [`Quad`] primitive, in a 2D scene. | ^^^^ no item named `Quad` in scope | = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]` = note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default warning: `bevy` (example "mesh2d") generated 1 warning warning: unresolved link to `update_weights` --> examples/animation/morph_targets.rs:6:17 | 6 | //! See the [`update_weights`] system for details. | ^^^^^^^^^^^^^^ no item named `update_weights` in scope | = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]` = note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default warning: public documentation for `morph_targets` links to private item `name_morphs` --> examples/animation/morph_targets.rs:7:43 | 7 | //! - How to read morph target names in [`name_morphs`]. | ^^^^^^^^^^^ this item is private | = note: this link will resolve properly if you pass `--document-private-items` = note: `#[warn(rustdoc::private_intra_doc_links)]` on by default warning: public documentation for `morph_targets` links to private item `setup_animations` --> examples/animation/morph_targets.rs:8:48 | 8 | //! - How to play morph target animations in [`setup_animations`]. | ^^^^^^^^^^^^^^^^ this item is private | = note: this link will resolve properly if you pass `--document-private-items` warning: `bevy` (example "morph_targets") generated 3 warnings warning: unresolved link to `Quad` --> examples/2d/mesh2d_vertex_color_texture.rs:1:66 | 1 | //! Shows how to render a polygonal [`Mesh`], generated from a [`Quad`] primitive, in a 2D scene. | ^^^^ no item named `Quad` in scope | = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]` = note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default warning: `bevy` (example "mesh2d_vertex_color_texture") generated 1 warning warning: unresolved link to `UIScale` --> examples/ui/ui_scaling.rs:1:36 | 1 | //! This example illustrates the [`UIScale`] resource from `bevy_ui`. | ^^^^^^^ no item named `UIScale` in scope | = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]` = note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default warning: `bevy` (example "ui_scaling") generated 1 warning warning: unresolved link to `dependencies` --> examples/app/headless.rs:5:6 | 5 | //! [dependencies] | ^^^^^^^^^^^^ no item named `dependencies` in scope | = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]` = note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default warning: `bevy` (example "headless") generated 1 warning warning: unresolved link to `Material2d` --> examples/2d/mesh2d_manual.rs:3:26 | 3 | //! It doesn't use the [`Material2d`] abstraction, but changes the vertex buffer to include verte... | ^^^^^^^^^^ no item named `Material2d` in scope | = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]` = note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default warning: `bevy` (example "mesh2d_manual") generated 1 warning ```
2023-11-08 14:33:46 +00:00
//!
//! [`Quad`]: shape::Quad
use bevy::{prelude::*, sprite::MaterialMesh2dBundle};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.run();
}
fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<ColorMaterial>>,
) {
Spawn now takes a Bundle (#6054) # Objective Now that we can consolidate Bundles and Components under a single insert (thanks to #2975 and #6039), almost 100% of world spawns now look like `world.spawn().insert((Some, Tuple, Here))`. Spawning an entity without any components is an extremely uncommon pattern, so it makes sense to give spawn the "first class" ergonomic api. This consolidated api should be made consistent across all spawn apis (such as World and Commands). ## Solution All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input: ```rust // before: commands .spawn() .insert((A, B, C)); world .spawn() .insert((A, B, C); // after commands.spawn((A, B, C)); world.spawn((A, B, C)); ``` All existing instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api. A new `spawn_empty` has been added, replacing the old `spawn` api. By allowing `world.spawn(some_bundle)` to replace `world.spawn().insert(some_bundle)`, this opened the door to removing the initial entity allocation in the "empty" archetype / table done in `spawn()` (and subsequent move to the actual archetype in `.insert(some_bundle)`). This improves spawn performance by over 10%: ![image](https://user-images.githubusercontent.com/2694663/191627587-4ab2f949-4ccd-4231-80eb-80dd4d9ad6b9.png) To take this measurement, I added a new `world_spawn` benchmark. Unfortunately, optimizing `Commands::spawn` is slightly less trivial, as Commands expose the Entity id of spawned entities prior to actually spawning. Doing the optimization would (naively) require assurances that the `spawn(some_bundle)` command is applied before all other commands involving the entity (which would not necessarily be true, if memory serves). Optimizing `Commands::spawn` this way does feel possible, but it will require careful thought (and maybe some additional checks), which deserves its own PR. For now, it has the same performance characteristics of the current `Commands::spawn_bundle` on main. **Note that 99% of this PR is simple renames and refactors. The only code that needs careful scrutiny is the new `World::spawn()` impl, which is relatively straightforward, but it has some new unsafe code (which re-uses battle tested BundlerSpawner code path).** --- ## Changelog - All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input - All instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api - World and Commands now have `spawn_empty()`, which is equivalent to the old `spawn()` behavior. ## Migration Guide ```rust // Old (0.8): commands .spawn() .insert_bundle((A, B, C)); // New (0.9) commands.spawn((A, B, C)); // Old (0.8): commands.spawn_bundle((A, B, C)); // New (0.9) commands.spawn((A, B, C)); // Old (0.8): let entity = commands.spawn().id(); // New (0.9) let entity = commands.spawn_empty().id(); // Old (0.8) let entity = world.spawn().id(); // New (0.9) let entity = world.spawn_empty(); ```
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commands.spawn(Camera2dBundle::default());
commands.spawn(MaterialMesh2dBundle {
Use `impl Into<A>` for `Assets::add` (#10878) # Motivation When spawning entities into a scene, it is very common to create assets like meshes and materials and to add them via asset handles. A common setup might look like this: ```rust fn setup( mut commands: Commands, mut meshes: ResMut<Assets<Mesh>>, mut materials: ResMut<Assets<StandardMaterial>>, ) { commands.spawn(PbrBundle { mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })), material: materials.add(StandardMaterial::from(Color::RED)), ..default() }); } ``` Let's take a closer look at the part that adds the assets using `add`. ```rust mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })), material: materials.add(StandardMaterial::from(Color::RED)), ``` Here, "mesh" and "material" are both repeated three times. It's very explicit, but I find it to be a bit verbose. In addition to being more code to read and write, the extra characters can sometimes also lead to the code being formatted to span multiple lines even though the core task, adding e.g. a primitive mesh, is extremely simple. A way to address this is by using `.into()`: ```rust mesh: meshes.add(shape::Cube { size: 1.0 }.into()), material: materials.add(Color::RED.into()), ``` This is fine, but from the names and the type of `meshes`, we already know what the type should be. It's very clear that `Cube` should be turned into a `Mesh` because of the context it's used in. `.into()` is just seven characters, but it's so common that it quickly adds up and gets annoying. It would be nice if you could skip all of the conversion and let Bevy handle it for you: ```rust mesh: meshes.add(shape::Cube { size: 1.0 }), material: materials.add(Color::RED), ``` # Objective Make adding assets more ergonomic by making `Assets::add` take an `impl Into<A>` instead of `A`. ## Solution `Assets::add` now takes an `impl Into<A>` instead of `A`, so e.g. this works: ```rust commands.spawn(PbrBundle { mesh: meshes.add(shape::Cube { size: 1.0 }), material: materials.add(Color::RED), ..default() }); ``` I also changed all examples to use this API, which increases consistency as well because `Mesh::from` and `into` were being used arbitrarily even in the same file. This also gets rid of some lines of code because formatting is nicer. --- ## Changelog - `Assets::add` now takes an `impl Into<A>` instead of `A` - Examples don't use `T::from(K)` or `K.into()` when adding assets ## Migration Guide Some `into` calls that worked previously might now be broken because of the new trait bounds. You need to either remove `into` or perform the conversion explicitly with `from`: ```rust // Doesn't compile let mesh_handle = meshes.add(shape::Cube { size: 1.0 }.into()), // These compile let mesh_handle = meshes.add(shape::Cube { size: 1.0 }), let mesh_handle = meshes.add(Mesh::from(shape::Cube { size: 1.0 })), ``` ## Concerns I believe the primary concerns might be: 1. Is this too implicit? 2. Does this increase codegen bloat? Previously, the two APIs were using `into` or `from`, and now it's "nothing" or `from`. You could argue that `into` is slightly more explicit than "nothing" in cases like the earlier examples where a `Color` gets converted to e.g. a `StandardMaterial`, but I personally don't think `into` adds much value even in this case, and you could still see the actual type from the asset type. As for codegen bloat, I doubt it adds that much, but I'm not very familiar with the details of codegen. I personally value the user-facing code reduction and ergonomics improvements that these changes would provide, but it might be worth checking the other effects in more detail. Another slight concern is migration pain; apps might have a ton of `into` calls that would need to be removed, and it did take me a while to do so for Bevy itself (maybe around 20-40 minutes). However, I think the fact that there *are* so many `into` calls just highlights that the API could be made nicer, and I'd gladly migrate my own projects for it.
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mesh: meshes.add(shape::Quad::default()).into(),
transform: Transform::default().with_scale(Vec3::splat(128.)),
material: materials.add(Color::PURPLE),
..default()
});
}