cb64a4aa8a
# Objective Make use of let chains to reduce LoC where we previously used let else to cut down on indentation. Best of both worlds.
69 lines
1.9 KiB
Rust
69 lines
1.9 KiB
Rust
//! This example demonstrates how to use the `Camera::viewport_to_world` method.
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use bevy::prelude::*;
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.add_systems(Startup, setup)
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.add_systems(Update, draw_cursor)
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.run();
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}
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fn draw_cursor(
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camera_query: Single<(&Camera, &GlobalTransform)>,
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ground: Single<&GlobalTransform, With<Ground>>,
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window: Single<&Window>,
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mut gizmos: Gizmos,
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) {
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let (camera, camera_transform) = *camera_query;
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if let Some(cursor_position) = window.cursor_position()
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// Calculate a ray pointing from the camera into the world based on the cursor's position.
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&& let Ok(ray) = camera.viewport_to_world(camera_transform, cursor_position)
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// Calculate if and at what distance the ray is hitting the ground plane.
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&& let Some(distance) =
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ray.intersect_plane(ground.translation(), InfinitePlane3d::new(ground.up()))
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{
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let point = ray.get_point(distance);
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// Draw a circle just above the ground plane at that position.
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gizmos.circle(
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Isometry3d::new(
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point + ground.up() * 0.01,
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Quat::from_rotation_arc(Vec3::Z, ground.up().as_vec3()),
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),
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0.2,
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Color::WHITE,
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);
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}
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}
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#[derive(Component)]
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struct Ground;
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fn setup(
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mut commands: Commands,
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mut meshes: ResMut<Assets<Mesh>>,
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mut materials: ResMut<Assets<StandardMaterial>>,
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) {
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// plane
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commands.spawn((
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Mesh3d(meshes.add(Plane3d::default().mesh().size(20., 20.))),
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MeshMaterial3d(materials.add(Color::srgb(0.3, 0.5, 0.3))),
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Ground,
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));
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// light
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commands.spawn((
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DirectionalLight::default(),
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Transform::from_translation(Vec3::ONE).looking_at(Vec3::ZERO, Vec3::Y),
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));
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// camera
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commands.spawn((
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Camera3d::default(),
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Transform::from_xyz(15.0, 5.0, 15.0).looking_at(Vec3::ZERO, Vec3::Y),
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));
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}
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