Wind!

src/main.rs

@@ -24,10 +24,20 @@ struct SailboatState {
     rudder_dir: f32,
 }
 
+#[derive(Default, Resource)]
+struct WindConditions {
+    direction: f32,
+    strength: f32,
+}
+
 fn main() {
     let mut app = App::new();
 
     app.add_plugins((DefaultPlugins, Wireframe2dPlugin::default()))
+        .insert_resource(WindConditions {
+            strength: 1.0,
+            ..default()
+        })
         .add_systems(Startup, (hello_world, camera_setup, sprite_setup).chain())
         .add_systems(Update, (handle_keys, player_physics).chain());
 
@@ -107,11 +117,47 @@ fn player_physics(
         &mut EntityPhysics,
         &mut Transform,
     )>,
+    wind_conditions: Res<WindConditions>,
 ) {
     let Ok((input, mut boat_state, mut physics, mut transform)) = q_player.single_mut() else {
         return;
     };
 
+    if input.y > 0. {
+        boat_state.sail_extension = (1.0 + boat_state.sail_extension) * 0.5;
+    } else if input.y < 0. {
+        boat_state.sail_extension *= 0.5;
+    }
+
+    boat_state.sail_extension = boat_state.sail_extension.clamp(0., 1.);
+
+    physics.speed *= 0.99;
+
+    let sail_speed_x = physics.heading.sin();
+    let sail_speed_y = physics.heading.cos();
+
+    let wind_speed_x = wind_conditions.direction.sin();
+    let wind_speed_y = wind_conditions.direction.cos();
+
+    let sail_speed_vec = Vec2 {
+        x: sail_speed_x,
+        y: sail_speed_y,
+    };
+    let wind_speed_vec = Vec2 {
+        x: wind_speed_x,
+        y: wind_speed_y,
+    };
+
+    // technically you could put your sail out and try to go backwards but..
+    // let's not tackle that (Yet?)
+    let sail_strength = sail_speed_vec.dot(wind_speed_vec).clamp(0., 1.);
+
+    if boat_state.sail_extension > 0. {
+        physics.speed += 0.01 * boat_state.sail_extension * sail_strength;
+    }
+
+    physics.speed = physics.speed.clamp(-MAX_SAILING_SPEED, MAX_SAILING_SPEED);
+
     if input.x < 0. {
         boat_state.rudder_dir = (-1.0 + boat_state.rudder_dir) * 0.5;
     } else if input.x > 0. {
@@ -127,22 +173,6 @@ fn player_physics(
     physics.turn_speed = physics.turn_speed.clamp(-MAX_TURN_SPEED, MAX_TURN_SPEED);
     physics.heading += physics.turn_speed * 0.1;
 
-    if input.y > 0. {
-        boat_state.sail_extension = (1.0 + boat_state.sail_extension) * 0.5;
-    } else if input.y < 0. {
-        boat_state.sail_extension *= 0.5;
-    }
-
-    boat_state.sail_extension = boat_state.sail_extension.clamp(0., 1.);
-
-    physics.speed *= 0.99;
-
-    if boat_state.sail_extension > 0. {
-        physics.speed += 0.01 * boat_state.sail_extension;
-    }
-
-    physics.speed = physics.speed.clamp(-MAX_SAILING_SPEED, MAX_SAILING_SPEED);
-
     let x_speed = physics.heading.sin() * physics.speed;
     let y_speed = physics.heading.cos() * physics.speed;