pong: reset counter on idle and increase idle length

src/pong.ts

@@ -45,6 +45,7 @@ class Paddle {
     isLeft: boolean;
     score: number;
     dy: number;
+    idleCounter: number;
 
     constructor(_geometry: Box, _isLeft: boolean) {
         this.geometry = _geometry;
@@ -53,6 +54,7 @@ class Paddle {
         this.isBot = true;
         this.score = 0;
         this.dy = 0;
+        this.idleCounter = 0;
     }
 
     scored() {
@@ -122,8 +124,13 @@ class PongCore {
 
     // Simulate game logic
     simulate() {
-        this.botInput(this.left);
-        this.botInput(this.right);
+        if (this.ball.dx < 0) {
+            this.botInput(this.left);
+            this.botIdle(this.right);
+        } else {
+            this.botInput(this.right);
+            this.botIdle(this.left);
+        }
 
         // move paddles by their velocity
         this.left.geometry.y += this.left.dy;
@@ -246,6 +253,27 @@ class PongCore {
         if (ballRegion > paddleRegion) player.dy = player.speed; 
         if (ballRegion === paddleRegion) player.dy = 0; 
     }
+
+    // Randomly move the bot paddle when ball not towards it
+    botIdle(player: Paddle) {
+        player.idleCounter++;
+        if (player.idleCounter < 20)
+            return;
+        else
+            player.idleCounter = 0;
+        let direction: number = Math.floor(Math.random() * 3);
+        switch (direction) {
+            case 0:
+                player.dy = 0;
+                break;
+            case 1:
+                player.dy = -player.speed;
+                break;
+            case 2:
+                player.dy = player.speed;
+                break;
+        }
+    }
 }
 
 // listen to keyboard events to move the paddles