Add camera and reset controls

src/main.rs

@@ -1,35 +1,92 @@
-use bevy::{prelude::*, render::pass::ClearColor};
+use bevy::{
+    diagnostic::{FrameTimeDiagnosticsPlugin, PrintDiagnosticsPlugin},
+    input::keyboard::{ElementState, KeyboardInput},
+    input::mouse::{MouseButtonInput, MouseMotion},
+    prelude::*,
+    render::camera::{Camera, OrthographicProjection},
+    render::pass::ClearColor,
+    window::CursorMoved,
+};
 use bigbang::{Entity, GravTree};
 use rand::Rng;
 
 struct Simulation(GravTree<Entity>);
 
+#[derive(Default)]
+struct State {
+    mouse_button_event_reader: EventReader<MouseButtonInput>,
+    mouse_motion_event_reader: EventReader<MouseMotion>,
+    cursor_moved_event_reader: EventReader<CursorMoved>,
+    keyboard_event_reader: EventReader<KeyboardInput>,
+    cursor_position: Option<Vec2>,
+    zooming: bool,
+    panning: bool,
+    follow_body_index: Option<usize>,
+}
+
+static INITIAL_WIDTH: u32 = 1280;
+static INITIAL_HEIGHT: u32 = 720;
+static INITIAL_SCALE: f32 = 10.;
+static TIME_STEP: f64 = 0.02;
+static NUM_BODIES: u32 = 100;
+
 fn main() {
-    let mut rng = rand::thread_rng();
-    let mut bodies = vec![];
-    for _ in 0..100 {
-        bodies.push(Entity {
-            x: rng.gen_range(-400., 400.),
-            y: rng.gen_range(-400., 400.),
-            z: 0.,
-            vx: rng.gen_range(-20., 20.),
-            vy: rng.gen_range(-20., 20.),
-            vz: 0.,
-            mass: rng.gen_range(1., 20.),
-            radius: rng.gen_range(1., 10.),
-        });
-    }
     App::build()
         .add_resource(Msaa { samples: 4 })
+        .add_resource(WindowDescriptor {
+            title: "bevy-nbody".to_string(),
+            width: INITIAL_WIDTH,
+            height: INITIAL_HEIGHT,
+            ..Default::default()
+        })
         .add_default_plugins()
+        .add_plugin(FrameTimeDiagnosticsPlugin::default())
+        .add_plugin(PrintDiagnosticsPlugin::default())
+        .init_resource::<State>()
         .add_resource(ClearColor(Color::rgb(0.01, 0.01, 0.01)))
-        .add_resource(Simulation(GravTree::new(&bodies, 0.02)))
+        .add_resource(Simulation(GravTree::new(
+            &initialize_bodies(INITIAL_WIDTH, INITIAL_HEIGHT, INITIAL_SCALE),
+            TIME_STEP,
+        )))
         .add_startup_system(add_bodies.system())
         .add_system(time_step.system())
         .add_system(update_bodies.system())
+        .add_system(follow.system())
+        .add_system(mouse_input.system())
+        .add_system(keyboard_input.system())
         .run();
 }
 
+fn initialize_bodies(width: u32, height: u32, scale: f32) -> Vec<Entity> {
+    let mut rng = rand::thread_rng();
+    let mut bodies = vec![];
+    for i in 0..NUM_BODIES {
+        let mass = if i == 0 {
+            // big boi
+            rng.gen_range(500., 1500.)
+        } else {
+            rng.gen_range(50., 500.)
+        };
+        bodies.push(Entity {
+            x: rng.gen_range(
+                -(width as f64 / 2.) * scale as f64,
+                (width as f64 / 2.) * scale as f64,
+            ),
+            y: rng.gen_range(
+                -(height as f64 / 2.) * scale as f64,
+                (height as f64 / 2.) * scale as f64,
+            ),
+            z: 0.,
+            vx: rng.gen_range(-50., 50.),
+            vy: rng.gen_range(-50., 50.),
+            vz: 0.,
+            mass,
+            radius: mass / 30.,
+        });
+    }
+    bodies
+}
+
 fn add_bodies(
     mut commands: Commands,
     mut materials: ResMut<Assets<ColorMaterial>>,
@@ -37,21 +94,30 @@ fn add_bodies(
     asset_server: Res<AssetServer>,
     grav_tree: Res<Simulation>,
 ) {
+    let mut rng = rand::thread_rng();
     let texture = asset_server.load("assets/circle.png").unwrap();
-    // TODO: texture transparency not working
-    commands
-        .spawn(Camera2dComponents::default())
-        .spawn(UiCameraComponents::default());
+    commands.spawn(Camera2dComponents {
+        scale: Scale(INITIAL_SCALE),
+        ..Camera2dComponents::default()
+    });
 
+    let mut index = 0;
     for body in grav_tree.0.as_vec() {
         commands
             .spawn(SpriteComponents {
                 mesh: meshes.add(Mesh::from(shape::Quad::new(Vec2::new(
-                    (body.radius / 100.) as f32,
-                    (body.radius / 100.) as f32,
+                    (body.radius / 10.) as f32,
+                    (body.radius / 10.) as f32,
                 )))),
-                material: materials.add(texture.into()),
-                translation: Translation(Vec3::new(body.x as f32, body.y as f32, body.z as f32)),
+                material: materials.add(ColorMaterial {
+                    color: Color::rgb(
+                        rng.gen_range(0.8, 1.),
+                        rng.gen_range(0., 0.6),
+                        rng.gen_range(0., 0.05),
+                    ),
+                    texture: texture.into(),
+                }),
+                translation: Translation(Vec3::new(body.x as f32, body.y as f32, index as f32)),
                 draw: Draw {
                     is_transparent: true,
                     ..Default::default()
@@ -59,6 +125,7 @@ fn add_bodies(
                 ..Default::default()
             })
             .with(body);
+        index += 1;
     }
 }
 
@@ -68,16 +135,141 @@ fn time_step(mut grav_tree: ResMut<Simulation>) {
 
 fn update_bodies(grav_tree: Res<Simulation>, mut body_query: Query<(&Entity, &mut Translation)>) {
     let updated_bodies = grav_tree.0.as_vec();
-    // for body in updated_bodies.iter() {
-    //     println!("body: {}", body.as_string());
-    // }
-
     let mut index = 0;
     for (_, mut translation) in &mut body_query.iter() {
         let updated_body = &updated_bodies[index];
         translation.0.set_x(updated_body.x as f32);
         translation.0.set_y(updated_body.y as f32);
-        translation.0.set_z(updated_body.z as f32);
         index += 1;
     }
 }
+
+fn screen_to_translation_coord(
+    screen_coord: Vec2,
+    projection: &OrthographicProjection,
+    translation: &Translation,
+    scale: &Scale,
+) -> Vec2 {
+    Vec2::new(
+        ((projection.left + screen_coord.x()) * scale.0) + translation.x(),
+        ((projection.bottom + screen_coord.y()) * scale.0) + translation.y(),
+    )
+}
+
+fn mouse_input(
+    mut state: ResMut<State>,
+    grav_tree: Res<Simulation>,
+    mouse_button_input_events: Res<Events<MouseButtonInput>>,
+    mouse_motion_events: Res<Events<MouseMotion>>,
+    cursor_moved_events: Res<Events<CursorMoved>>,
+    mut query: Query<(
+        &mut Camera,
+        &mut Scale,
+        &mut Translation,
+        &mut OrthographicProjection,
+    )>,
+) {
+    for event in state
+        .mouse_button_event_reader
+        .iter(&mouse_button_input_events)
+    {
+        if event.button == MouseButton::Middle && event.state == ElementState::Pressed {
+            state.zooming = true;
+        } else if event.button == MouseButton::Middle && event.state == ElementState::Released {
+            state.zooming = false;
+        } else if event.button == MouseButton::Left && event.state == ElementState::Pressed {
+            state.panning = true;
+            state.follow_body_index = None;
+        } else if event.button == MouseButton::Left && event.state == ElementState::Released {
+            state.panning = false;
+        } else if event.button == MouseButton::Right && event.state == ElementState::Released {
+            if let Some(position) = state.cursor_position {
+                for (_, scale, translation, projection) in &mut query.iter() {
+                    if let Some((closest_index, _)) = grav_tree
+                        .0
+                        .as_vec()
+                        .into_iter()
+                        .enumerate()
+                        .find(|(_, body)| {
+                            let hit_slop = body.radius as f32 * 2. + (10. * scale.0);
+                            let translation_coord = screen_to_translation_coord(
+                                position,
+                                &projection,
+                                &translation,
+                                &scale,
+                            );
+                            if (translation_coord.x() - body.x as f32).abs() <= hit_slop
+                                && (translation_coord.y() - body.y as f32).abs() <= hit_slop
+                            {
+                                return true;
+                            }
+                            false
+                        })
+                    {
+                        state.follow_body_index = Some(closest_index);
+                    } else {
+                        state.follow_body_index = None;
+                    }
+                }
+            }
+        }
+    }
+
+    for event in state.mouse_motion_event_reader.iter(&mouse_motion_events) {
+        if state.zooming || state.panning {
+            for (_, mut scale, mut translation, _) in &mut query.iter() {
+                if state.zooming {
+                    scale.0 += (event.delta.y() / 500.) * (scale.0 / 3.);
+                }
+                if state.panning {
+                    *translation.x_mut() -= event.delta.x() * (scale.0 / 3.);
+                    *translation.y_mut() += event.delta.y() * (scale.0 / 3.);
+                }
+            }
+        }
+    }
+
+    for event in state.cursor_moved_event_reader.iter(&cursor_moved_events) {
+        state.cursor_position = Some(event.position);
+    }
+}
+
+fn keyboard_input(
+    mut state: ResMut<State>,
+    keyboard_input_events: Res<Events<KeyboardInput>>,
+    mut grav_tree: ResMut<Simulation>,
+    windows: Res<Windows>,
+    mut query: Query<(&Camera, &Scale, &mut Translation)>,
+) {
+    for event in state.keyboard_event_reader.iter(&keyboard_input_events) {
+        if let Some(key_code) = event.key_code {
+            if key_code == KeyCode::R {
+                for (_, scale, mut translation) in &mut query.iter() {
+                    if let Some(window) = windows.get_primary() {
+                        translation.0.set_x(0.);
+                        translation.0.set_y(0.);
+                        grav_tree.0 = GravTree::new(
+                            &initialize_bodies(window.width, window.height, scale.0),
+                            TIME_STEP,
+                        );
+                    }
+                }
+            }
+        }
+    }
+}
+
+fn follow(
+    state: Res<State>,
+    mut body_query: Query<(&Entity, &mut Translation)>,
+    mut camera_query: Query<(&mut Camera, &mut Translation)>,
+) {
+    if let Some(follow_body_index) = state.follow_body_index {
+        for (_, mut translation) in &mut camera_query.iter() {
+            if let Some((_, body_translation)) = body_query.iter().iter().nth(follow_body_index) {
+                translation.0.set_x(body_translation.0.x());
+                translation.0.set_y(body_translation.0.y());
+            }
+        }
+    }
+}