accelerate ball

Author: juan-medina

src/pong.rs

@@ -34,8 +34,11 @@ const PADDLE_Z: f32 = Z_BACK;
 const PADDLE_SPRITE_NUM: usize = 0;
 
 const BALL_RADIUS: f32 = 2.0;
-const BALL_VELOCITY_X: f32 = 25.0;
+const BALL_VELOCITY_X: f32 = 30.0;
 const BALL_VELOCITY_Y: f32 = 15.0;
+const BALL_ACCELERATION: f32 = 0.2;
+const MAX_BALL_VELOCITY_X: f32 = BALL_VELOCITY_X * 2.0;
+const MAX_BALL_VELOCITY_Y: f32 = BALL_VELOCITY_Y * 2.0;
 pub const BALL_Z: f32 = Z_BACK;
 const BALL_SPRITE_NUM: usize = 1;
 
@@ -88,6 +91,7 @@ pub enum BallState {
 
 pub struct Ball {
     pub velocity: [f32; 2],
+    pub acceleration: f32,
     pub radius: f32,
     pub state: BallState,
     pub waiting_time: f32,
@@ -99,6 +103,11 @@ impl Ball {
         self.waiting_time = 2.0;
         self.velocity = [BALL_VELOCITY_X, BALL_VELOCITY_Y]
     }
+    pub fn accelerate(&mut self) {
+        let velocity_x = (self.velocity[0] + (self.velocity[0] * self.acceleration)).min(MAX_BALL_VELOCITY_X);
+        let velocity_y = (self.velocity[1] + (self.velocity[1] * self.acceleration)).min(MAX_BALL_VELOCITY_Y);
+        self.velocity = [velocity_x, velocity_y]
+    }
 }
 
 impl Component for Ball {
@@ -172,6 +181,7 @@ fn initialise_ball(world: &mut World, sprite_sheet_handle: Handle<SpriteSheet>)
         .with(Ball {
             radius: BALL_RADIUS,
             velocity: [BALL_VELOCITY_X, BALL_VELOCITY_Y],
+            acceleration: BALL_ACCELERATION,
             state: BallState::Waiting,
             waiting_time: 2.0,
         })

src/systems/bounce.rs

@@ -39,6 +39,7 @@ impl<'s> System<'s> for BounceSystem {
                 || (ball_y >= ARENA_HEIGHT - ball.radius && ball.velocity[1] > 0.0)
             {
                 ball.velocity[1] = -ball.velocity[1];
+                ball.accelerate();
                 play_bounce(&*sounds, &storage, audio_output.as_ref().map(|o| o.deref()));
             }
 
@@ -64,6 +65,7 @@ impl<'s> System<'s> for BounceSystem {
                         || (paddle.side == Side::Right && ball.velocity[0] > 0.0)
                     {
                         ball.velocity[0] = -ball.velocity[0];
+                        ball.accelerate();
                         play_bounce(&*sounds, &storage, audio_output.as_ref().map(|o| o.deref()));
                     }
                 }