bevy/examples/3d/wireframe.rs
Joona Aalto a795de30b4
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.
2024-01-08 22:14:43 +00:00

165 lines
4.9 KiB
Rust

//! Showcases wireframe rendering.
//!
//! Wireframes currently do not work when using webgl or webgpu.
//! Supported platforms:
//! - DX12
//! - Vulkan
//! - Metal
//!
//! This is a native only feature.
use bevy::{
pbr::wireframe::{NoWireframe, Wireframe, WireframeColor, WireframeConfig, WireframePlugin},
prelude::*,
render::{
render_resource::WgpuFeatures,
settings::{RenderCreation, WgpuSettings},
RenderPlugin,
},
};
fn main() {
App::new()
.add_plugins((
DefaultPlugins.set(RenderPlugin {
render_creation: RenderCreation::Automatic(WgpuSettings {
// WARN this is a native only feature. It will not work with webgl or webgpu
features: WgpuFeatures::POLYGON_MODE_LINE,
..default()
}),
}),
// You need to add this plugin to enable wireframe rendering
WireframePlugin,
))
// Wireframes can be configured with this resource. This can be changed at runtime.
.insert_resource(WireframeConfig {
// The global wireframe config enables drawing of wireframes on every mesh,
// except those with `NoWireframe`. Meshes with `Wireframe` will always have a wireframe,
// regardless of the global configuration.
global: true,
// Controls the default color of all wireframes. Used as the default color for global wireframes.
// Can be changed per mesh using the `WireframeColor` component.
default_color: Color::WHITE,
})
.add_systems(Startup, setup)
.add_systems(Update, update_colors)
.run();
}
/// set up a simple 3D scene
fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
// plane
commands.spawn(PbrBundle {
mesh: meshes.add(shape::Plane::from_size(5.0)),
material: materials.add(Color::BLUE),
..default()
});
// Red cube: Never renders a wireframe
commands.spawn((
PbrBundle {
mesh: meshes.add(shape::Cube { size: 1.0 }),
material: materials.add(Color::RED),
transform: Transform::from_xyz(-1.0, 0.5, -1.0),
..default()
},
NoWireframe,
));
// Orange cube: Follows global wireframe setting
commands.spawn(PbrBundle {
mesh: meshes.add(shape::Cube { size: 1.0 }),
material: materials.add(Color::ORANGE),
transform: Transform::from_xyz(0.0, 0.5, 0.0),
..default()
});
// Green cube: Always renders a wireframe
commands.spawn((
PbrBundle {
mesh: meshes.add(shape::Cube { size: 1.0 }),
material: materials.add(Color::GREEN),
transform: Transform::from_xyz(1.0, 0.5, 1.0),
..default()
},
Wireframe,
// This lets you configure the wireframe color of this entity.
// If not set, this will use the color in `WireframeConfig`
WireframeColor {
color: Color::GREEN,
},
));
// light
commands.spawn(PointLightBundle {
transform: Transform::from_xyz(4.0, 8.0, 4.0),
..default()
});
// camera
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
// Text used to show controls
commands.spawn(
TextBundle::from_section("", TextStyle::default()).with_style(Style {
position_type: PositionType::Absolute,
top: Val::Px(10.0),
left: Val::Px(10.0),
..default()
}),
);
}
/// This system let's you toggle various wireframe settings
fn update_colors(
keyboard_input: Res<ButtonInput<KeyCode>>,
mut config: ResMut<WireframeConfig>,
mut wireframe_colors: Query<&mut WireframeColor>,
mut text: Query<&mut Text>,
) {
text.single_mut().sections[0].value = format!(
"
Controls
---------------
Z - Toggle global
X - Change global color
C - Change color of the green cube wireframe
WireframeConfig
-------------
Global: {}
Color: {:?}
",
config.global, config.default_color,
);
// Toggle showing a wireframe on all meshes
if keyboard_input.just_pressed(KeyCode::KeyZ) {
config.global = !config.global;
}
// Toggle the global wireframe color
if keyboard_input.just_pressed(KeyCode::KeyX) {
config.default_color = if config.default_color == Color::WHITE {
Color::PINK
} else {
Color::WHITE
};
}
// Toggle the color of a wireframe using WireframeColor and not the global color
if keyboard_input.just_pressed(KeyCode::KeyC) {
for mut color in &mut wireframe_colors {
color.color = if color.color == Color::GREEN {
Color::RED
} else {
Color::GREEN
};
}
}
}