bevy/examples/3d/3d_viewport_to_world.rs
Joona Aalto d9aac887b5
Split Ray into Ray2d and Ray3d and simplify plane construction (#10856)
# Objective

A better alternative version of #10843.

Currently, Bevy has a single `Ray` struct for 3D. To allow better
interoperability with Bevy's primitive shapes (#10572) and some third
party crates (that handle e.g. spatial queries), it would be very useful
to have separate versions for 2D and 3D respectively.

## Solution

Separate `Ray` into `Ray2d` and `Ray3d`. These new structs also take
advantage of the new primitives by using `Direction2d`/`Direction3d` for
the direction:

```rust
pub struct Ray2d {
    pub origin: Vec2,
    pub direction: Direction2d,
}

pub struct Ray3d {
    pub origin: Vec3,
    pub direction: Direction3d,
}
```

and by using `Plane2d`/`Plane3d` in `intersect_plane`:

```rust
impl Ray2d {
    // ...
    pub fn intersect_plane(&self, plane_origin: Vec2, plane: Plane2d) -> Option<f32> {
        // ...
    }
}
```

---

## Changelog

### Added

- `Ray2d` and `Ray3d`
- `Ray2d::new` and `Ray3d::new` constructors
- `Plane2d::new` and `Plane3d::new` constructors

### Removed

- Removed `Ray` in favor of `Ray3d`

### Changed

- `direction` is now a `Direction2d`/`Direction3d` instead of a vector,
which provides guaranteed normalization
- `intersect_plane` now takes a `Plane2d`/`Plane3d` instead of just a
vector for the plane normal
- `Direction2d` and `Direction3d` now derive `Serialize` and
`Deserialize` to preserve ray (de)serialization

## Migration Guide

`Ray` has been renamed to `Ray3d`.

### Ray creation

Before:

```rust
Ray {
    origin: Vec3::ZERO,
    direction: Vec3::new(0.5, 0.6, 0.2).normalize(),
}
```

After:

```rust
// Option 1:
Ray3d {
    origin: Vec3::ZERO,
    direction: Direction3d::new(Vec3::new(0.5, 0.6, 0.2)).unwrap(),
}

// Option 2:
Ray3d::new(Vec3::ZERO, Vec3::new(0.5, 0.6, 0.2))
```

### Plane intersections

Before:

```rust
let result = ray.intersect_plane(Vec2::X, Vec2::Y);
```

After:

```rust
let result = ray.intersect_plane(Vec2::X, Plane2d::new(Vec2::Y));
```
2023-12-06 14:09:04 +00:00

72 lines
2 KiB
Rust

//! This example demonstrates how to use the `Camera::viewport_to_world` method.
use bevy::prelude::*;
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.add_systems(Update, draw_cursor)
.run();
}
fn draw_cursor(
camera_query: Query<(&Camera, &GlobalTransform)>,
ground_query: Query<&GlobalTransform, With<Ground>>,
windows: Query<&Window>,
mut gizmos: Gizmos,
) {
let (camera, camera_transform) = camera_query.single();
let ground = ground_query.single();
let Some(cursor_position) = windows.single().cursor_position() else {
return;
};
// Calculate a ray pointing from the camera into the world based on the cursor's position.
let Some(ray) = camera.viewport_to_world(camera_transform, cursor_position) else {
return;
};
// Calculate if and where the ray is hitting the ground plane.
let Some(distance) =
ray.intersect_plane(ground.translation(), primitives::Plane3d::new(ground.up()))
else {
return;
};
let point = ray.get_point(distance);
// Draw a circle just above the ground plane at that position.
gizmos.circle(point + ground.up() * 0.01, ground.up(), 0.2, Color::WHITE);
}
#[derive(Component)]
struct Ground;
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(20.).into()),
material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
..default()
},
Ground,
));
// light
commands.spawn(DirectionalLightBundle {
transform: Transform::from_translation(Vec3::ONE).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
// camera
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(15.0, 5.0, 15.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
}