mirror of
https://github.com/bevyengine/bevy.git
synced 2026-05-06 06:06:42 -04:00
Chris Biscardi
07288e10a2
# Objective Address the 2d use case of rotating an entity to face the cursor in the minimal amount of code ## Solution New example ## Testing ``` cargo run --example rotate_to_cursor ``` --- ## Showcase https://github.com/user-attachments/assets/2f3aeade-5def-4fa3-a343-93985be55e57 --------- Co-authored-by: Joda <jodainteractive@protonmail.com>
60 lines
2.2 KiB
Rust
60 lines
2.2 KiB
Rust
//! Demonstrates rotating sprites to face the cursor.
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use bevy::prelude::*;
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use std::f32::consts::FRAC_PI_2;
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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(FixedUpdate, player_movement_system)
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.run();
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}
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/// Player component
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#[derive(Component)]
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struct Player;
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/// Add the game's entities to our world and create an orthographic camera for 2D rendering.
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///
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/// The Bevy coordinate system is the same for 2D and 3D, in terms of 2D this means that:
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///
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/// * `X` axis goes from left to right (`+X` points right)
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/// * `Y` axis goes from bottom to top (`+Y` point up)
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/// * `Z` axis goes from far to near (`+Z` points towards you, out of the screen)
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///
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/// The world origin in this case is at the center of the screen, but the camera could
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/// move in which case the world origin would not be the center of the screen
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fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
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let ship_handle = asset_server.load("textures/simplespace/ship_C.png");
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commands.spawn(Camera2d);
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// Player controlled ship
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commands.spawn((Sprite::from_image(ship_handle), Player));
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}
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/// Demonstrates applying rotation and movement based on keyboard input.
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fn player_movement_system(
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mut player: Single<&mut Transform, With<Player>>,
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camera_query: Single<(&Camera, &GlobalTransform)>,
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window: Single<&Window>,
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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 world position based on the cursor's position.
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&& let Ok(cursor_world_pos) = camera.viewport_to_world_2d(camera_transform, cursor_position)
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{
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// The angle an entity needs to rotate to face a point is defined
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// by the vector between the two points (Vec2 - Vec2), which we can then
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// turn into radians using to_angle.
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//
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// FRAC_PI_2 is because our sprite's ship is facing "up" so we rotate it an additional 90 degrees
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// so that it faces the cursor.
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player.rotation = Quat::from_rotation_z(
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(cursor_world_pos - player.translation.xy()).to_angle() - FRAC_PI_2,
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);
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}
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}
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