/**** 
* Plugins
****/ 
var tween = LK.import("@upit/tween.v1");

/**** 
* Classes
****/ 
var Bird = Container.expand(function () {
	var self = Container.call(this);
	var birdGraphics = self.attachAsset('bird', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.velocityX = 0;
	self.velocityY = 0;
	self.isLaunched = false;
	self.isActive = true;
	self.gravity = 0.5;
	self.hasUsedAbility = false;
	self.update = function () {
		if (self.isLaunched && self.isActive) {
			self.velocityY += self.gravity;
			self.x += self.velocityX;
			self.y += self.velocityY;
			// Check ground collision
			if (self.y >= groundY - 60) {
				self.y = groundY - 60;
				self.velocityX *= 0.5;
				self.velocityY = -self.velocityY * 0.6; // Bounce with 60% of velocity
				if (Math.abs(self.velocityX) < 0.5 && Math.abs(self.velocityY) < 0.5) {
					self.explode();
					self.isActive = false;
					checkLevelComplete();
				}
			}
			// Check screen boundaries
			if (self.x > 2048 + 100) {
				self.explode();
				self.isActive = false;
				checkLevelComplete();
			}
		}
	};
	self.launch = function (velX, velY) {
		self.velocityX = velX;
		self.velocityY = velY;
		self.isLaunched = true;
		LK.getSound('launch').play();
	};
	self.useAbility = function () {
		if (!self.hasUsedAbility && self.isLaunched) {
			self.hasUsedAbility = true;
			// Simple ability: speed boost
			self.velocityX *= 2.5;
			self.velocityY *= 2.5;
		}
	};
	self.explode = function () {
		// Create red feather particles
		for (var i = 0; i < 8; i++) {
			var feather = game.addChild(LK.getAsset('feather', {
				anchorX: 0.5,
				anchorY: 0.5,
				x: self.x,
				y: self.y,
				rotation: Math.random() * Math.PI * 2
			}));
			// Random velocity for each feather
			var angle = Math.PI * 2 * i / 8 + Math.random() * 0.5;
			var speed = 100 + Math.random() * 100;
			var targetX = self.x + Math.cos(angle) * speed;
			var targetY = self.y + Math.sin(angle) * speed;
			// Animate feather flying out and fading
			tween(feather, {
				x: targetX,
				y: targetY,
				alpha: 0,
				rotation: feather.rotation + Math.PI * 2,
				scaleX: 0.1,
				scaleY: 0.1
			}, {
				duration: 1000 + Math.random() * 500,
				easing: tween.easeOut,
				onFinish: function onFinish() {
					if (feather.parent) {
						feather.parent.removeChild(feather);
					}
				}
			});
		}
		// Make the bird disappear
		if (self.parent) {
			self.parent.removeChild(self);
		}
	};
	return self;
});
var Block = Container.expand(function (type) {
	var self = Container.call(this);
	var blockGraphics = self.attachAsset(type === 'wood' ? 'woodBlock' : 'stoneBlock', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.type = type;
	self.health = type === 'wood' ? 1 : 2;
	self.velocityX = 0;
	self.velocityY = 0;
	self.isActive = false;
	self.gravity = 0.3;
	self.update = function () {
		if (self.isActive) {
			self.velocityY += self.gravity;
			self.x += self.velocityX;
			self.y += self.velocityY;
			// Ground collision
			if (self.y >= groundY - 50) {
				self.y = groundY - 50;
				self.velocityX *= 0.3;
				self.velocityY = 0;
				if (Math.abs(self.velocityX) < 0.2) {
					self.isActive = false;
				}
			}
		}
	};
	self.takeDamage = function (damage, impactX, impactY) {
		self.health -= damage * 2;
		LK.getSound('hit').play();
		if (self.health <= 0) {
			self.destroy();
		} else {
			// Add some physics impact
			self.velocityX = (impactX - self.x) * 0.15;
			self.velocityY = (impactY - self.y) * 0.15;
			self.isActive = true;
		}
	};
	self.destroy = function () {
		LK.effects.flashObject(self, 0xffff00, 300);
		tween(self, {
			alpha: 0,
			rotation: Math.PI
		}, {
			duration: 1000,
			onFinish: function onFinish() {
				if (self.parent) {
					self.parent.removeChild(self);
				}
				var blockIndex = blocks.indexOf(self);
				if (blockIndex !== -1) {
					blocks.splice(blockIndex, 1);
				}
			}
		});
	};
	return self;
});
var Pig = Container.expand(function () {
	var self = Container.call(this);
	var pigGraphics = self.attachAsset('pig', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.isDestroyed = false;
	self.health = 1;
	self.takeDamage = function (damage) {
		self.health -= damage;
		if (self.health <= 0) {
			self.destroy();
		}
	};
	self.destroy = function () {
		if (!self.isDestroyed) {
			self.isDestroyed = true;
			LK.effects.flashObject(self, 0xff0000, 500);
			LK.getSound('destroy').play();
			tween(self, {
				alpha: 0,
				scaleX: 0.1,
				scaleY: 0.1
			}, {
				duration: 500,
				onFinish: function onFinish() {
					if (self.parent) {
						self.parent.removeChild(self);
					}
					var pigIndex = pigs.indexOf(self);
					if (pigIndex !== -1) {
						pigs.splice(pigIndex, 1);
					}
					checkLevelComplete();
				}
			});
		}
	};
	return self;
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x87CEEB
});

/**** 
* Game Code
****/ 
var groundY = 2732 - 100;
var slingshotX = 400;
var slingshotY = groundY - 150;
var birds = [];
var pigs = [];
var blocks = [];
var currentBird = null;
var trajectoryDots = [];
var isDragging = false;
var dragStartX = 0;
var dragStartY = 0;
var gameState = 'aiming'; // 'aiming', 'flying', 'waiting'
var levelComplete = false;
// Create ground
var ground = game.addChild(LK.getAsset('ground', {
	anchorX: 0,
	anchorY: 0,
	x: 0,
	y: groundY
}));
// Create slingshot
var slingshot = game.addChild(LK.getAsset('slingshot', {
	anchorX: 0.5,
	anchorY: 1,
	x: slingshotX,
	y: slingshotY
}));
// Create trajectory dots
for (var i = 0; i < 20; i++) {
	var dot = game.addChild(LK.getAsset('trajectory', {
		anchorX: 0.5,
		anchorY: 0.5,
		alpha: 0
	}));
	trajectoryDots.push(dot);
}
// Create level structure
function createLevel() {
	// Clear existing level
	while (birds.length > 0) {
		if (birds[0].parent) {
			birds[0].parent.removeChild(birds[0]);
		}
		birds.splice(0, 1);
	}
	while (pigs.length > 0) {
		if (pigs[0].parent) {
			pigs[0].parent.removeChild(pigs[0]);
		}
		pigs.splice(0, 1);
	}
	while (blocks.length > 0) {
		if (blocks[0].parent) {
			blocks[0].parent.removeChild(blocks[0]);
		}
		blocks.splice(0, 1);
	}
	// Create birds
	for (var i = 0; i < 3; i++) {
		var bird = new Bird();
		bird.x = slingshotX - 100 - i * 80;
		bird.y = slingshotY - 60;
		birds.push(bird);
		game.addChild(bird);
	}
	// Create multiple tower structures with pigs on top
	var towerPositions = [1200, 1500, 1800];
	var structureY = groundY;
	for (var towerIndex = 0; towerIndex < towerPositions.length; towerIndex++) {
		var structureX = towerPositions[towerIndex];
		// Create base level blocks (3 blocks wide)
		for (var i = 0; i < 3; i++) {
			var block = new Block('wood');
			block.x = structureX + i * 60;
			block.y = structureY - 50;
			blocks.push(block);
			game.addChild(block);
		}
		// Create second level blocks (2 blocks wide)
		for (var i = 0; i < 2; i++) {
			var block = new Block('wood');
			block.x = structureX + 30 + i * 60;
			block.y = structureY - 150;
			blocks.push(block);
			game.addChild(block);
		}
		// Create third level blocks (1 block wide)
		var block = new Block('wood');
		block.x = structureX + 60;
		block.y = structureY - 250;
		blocks.push(block);
		game.addChild(block);
		// Create fourth level blocks (1 block wide)
		var block = new Block('wood');
		block.x = structureX + 60;
		block.y = structureY - 350;
		blocks.push(block);
		game.addChild(block);
		// Create pigs on top of towers and around structures
		// Pig on top of tower (highest point)
		var pigTop = new Pig();
		pigTop.x = structureX + 60;
		pigTop.y = structureY - 500;
		pigs.push(pigTop);
		game.addChild(pigTop);
		// Pig on third level
		var pigThird = new Pig();
		pigThird.x = structureX + 60;
		pigThird.y = structureY - 400;
		pigs.push(pigThird);
		game.addChild(pigThird);
		// Pig on second level
		var pigSecond = new Pig();
		pigSecond.x = structureX + 60;
		pigSecond.y = structureY - 300;
		pigs.push(pigSecond);
		game.addChild(pigSecond);
		// Pigs around the base of the tower
		var pigLeft = new Pig();
		pigLeft.x = structureX - 30;
		pigLeft.y = structureY - 125;
		pigs.push(pigLeft);
		game.addChild(pigLeft);
		var pigRight = new Pig();
		pigRight.x = structureX + 150;
		pigRight.y = structureY - 125;
		pigs.push(pigRight);
		game.addChild(pigRight);
		// Pigs on first level blocks
		var pigFirst1 = new Pig();
		pigFirst1.x = structureX + 30;
		pigFirst1.y = structureY - 200;
		pigs.push(pigFirst1);
		game.addChild(pigFirst1);
		var pigFirst2 = new Pig();
		pigFirst2.x = structureX + 90;
		pigFirst2.y = structureY - 200;
		pigs.push(pigFirst2);
		game.addChild(pigFirst2);
	}
	// Set current bird
	currentBird = birds[0];
	currentBird.x = slingshotX;
	currentBird.y = slingshotY - 60;
	gameState = 'aiming';
	levelComplete = false;
}
function updateTrajectory(mouseX, mouseY) {
	var deltaX = mouseX - slingshotX;
	var deltaY = mouseY - slingshotY;
	var distance = Math.sqrt(deltaX * deltaX + deltaY * deltaY);
	if (distance > 150) {
		deltaX = deltaX / distance * 150;
		deltaY = deltaY / distance * 150;
	}
	var velocityX = -deltaX * 0.2;
	var velocityY = -deltaY * 0.2;
	for (var i = 0; i < trajectoryDots.length; i++) {
		var t = i * 3;
		var x = slingshotX + velocityX * t;
		var y = slingshotY - 60 + velocityY * t + 0.5 * 0.5 * t * t;
		trajectoryDots[i].x = x;
		trajectoryDots[i].y = y;
		trajectoryDots[i].alpha = Math.max(0, 1 - i * 0.05);
	}
}
function hideTrajectory() {
	for (var i = 0; i < trajectoryDots.length; i++) {
		trajectoryDots[i].alpha = 0;
	}
}
function checkCollisions() {
	if (!currentBird || !currentBird.isLaunched) return;
	// Check bird-pig collisions
	for (var i = 0; i < pigs.length; i++) {
		var pig = pigs[i];
		if (!pig.isDestroyed && currentBird.intersects(pig)) {
			pig.takeDamage(1);
			currentBird.explode();
			currentBird.isActive = false;
			checkLevelComplete();
			return;
		}
	}
	// Check bird-block collisions
	for (var i = 0; i < blocks.length; i++) {
		var block = blocks[i];
		if (currentBird.intersects(block)) {
			block.takeDamage(1, currentBird.x, currentBird.y);
			currentBird.explode();
			currentBird.isActive = false;
			checkLevelComplete();
			return;
		}
	}
}
function checkLevelComplete() {
	if (levelComplete) return;
	// Check if all blocks are destroyed
	var activeBlocks = 0;
	for (var i = 0; i < blocks.length; i++) {
		activeBlocks++;
	}
	if (activeBlocks === 0) {
		levelComplete = true;
		LK.setTimeout(function () {
			LK.showYouWin();
		}, 1000);
		return;
	}
	// Check if current bird is inactive and we need next bird
	if (currentBird && !currentBird.isActive && gameState === 'flying') {
		gameState = 'waiting';
		hideTrajectory();
		LK.setTimeout(function () {
			// Find next bird
			var nextBirdIndex = birds.indexOf(currentBird) + 1;
			if (nextBirdIndex < birds.length) {
				currentBird = birds[nextBirdIndex];
				currentBird.x = slingshotX;
				currentBird.y = slingshotY - 60;
				gameState = 'aiming';
			} else {
				// No more birds, game over
				LK.showGameOver();
			}
		}, 1000);
	}
}
// Game event handlers
game.down = function (x, y, obj) {
	if (gameState === 'aiming' && currentBird) {
		isDragging = true;
		dragStartX = x;
		dragStartY = y;
		updateTrajectory(x, y);
	}
};
game.move = function (x, y, obj) {
	if (isDragging && gameState === 'aiming' && currentBird) {
		var deltaX = x - slingshotX;
		var deltaY = y - slingshotY;
		var distance = Math.sqrt(deltaX * deltaX + deltaY * deltaY);
		if (distance > 150) {
			deltaX = deltaX / distance * 150;
			deltaY = deltaY / distance * 150;
		}
		currentBird.x = slingshotX + deltaX;
		currentBird.y = slingshotY - 60 + deltaY;
		updateTrajectory(x, y);
	}
};
game.up = function (x, y, obj) {
	if (isDragging && gameState === 'aiming' && currentBird) {
		isDragging = false;
		var deltaX = currentBird.x - slingshotX;
		var deltaY = currentBird.y - (slingshotY - 60);
		var velocityX = -deltaX * 0.2;
		var velocityY = -deltaY * 0.2;
		if (Math.abs(velocityX) > 1 || Math.abs(velocityY) > 1) {
			currentBird.launch(velocityX, velocityY);
			gameState = 'flying';
			hideTrajectory();
		} else {
			currentBird.x = slingshotX;
			currentBird.y = slingshotY - 60;
			hideTrajectory();
		}
	} else if (gameState === 'flying' && currentBird) {
		// Use bird ability
		currentBird.useAbility();
	}
};
game.update = function () {
	checkCollisions();
	// Update blocks physics
	for (var i = 0; i < blocks.length; i++) {
		var block = blocks[i];
		// Check block-pig collisions
		for (var j = 0; j < pigs.length; j++) {
			var pig = pigs[j];
			if (!pig.isDestroyed && block.intersects(pig)) {
				pig.takeDamage(1);
			}
		}
	}
};
// Create restart button in top right corner
var restartButton = game.addChild(LK.getAsset('restartButton', {
	anchorX: 0.5,
	anchorY: 0.5,
	x: 2048 - 100,
	y: 100
}));
// Create upward arrow on the button
var arrowUp = restartButton.addChild(LK.getAsset('arrowUp', {
	anchorX: 0.5,
	anchorY: 0.5,
	x: 0,
	y: -10,
	rotation: 0
}));
// Add click handler for restart button
restartButton.down = function (x, y, obj) {
	// Reset game state
	gameState = 'aiming';
	levelComplete = false;
	isDragging = false;
	currentBird = null;
	// Recreate the level
	createLevel();
	// Visual feedback
	tween(restartButton, {
		scaleX: 0.8,
		scaleY: 0.8
	}, {
		duration: 100,
		onFinish: function onFinish() {
			tween(restartButton, {
				scaleX: 1.0,
				scaleY: 1.0
			}, {
				duration: 100
			});
		}
	});
};
// Initialize level
createLevel();
;

===================================================================
--- original.js
+++ change.js
@@ -246,17 +246,23 @@
 // Create level structure
 function createLevel() {
 	// Clear existing level
 	while (birds.length > 0) {
-		birds[0].parent.removeChild(birds[0]);
+		if (birds[0].parent) {
+			birds[0].parent.removeChild(birds[0]);
+		}
 		birds.splice(0, 1);
 	}
 	while (pigs.length > 0) {
-		pigs[0].parent.removeChild(pigs[0]);
+		if (pigs[0].parent) {
+			pigs[0].parent.removeChild(pigs[0]);
+		}
 		pigs.splice(0, 1);
 	}
 	while (blocks.length > 0) {
-		blocks[0].parent.removeChild(blocks[0]);
+		if (blocks[0].parent) {
+			blocks[0].parent.removeChild(blocks[0]);
+		}
 		blocks.splice(0, 1);
 	}
 	// Create birds
 	for (var i = 0; i < 3; i++) {