Add randomPowerUpChance to Level type.

Allow defining said chance in level files.
Generate powerups on the fly when a brick is hit and the chance is met

core/src/com/me/brickbuster/entity/Brick.java

@@ -165,6 +165,11 @@ public class Brick extends Entity implements PhysicsBody, CollisionListener {
 			}
 		}
 
+		float powerUpChance = ((PlayState) state).currentLevel.getRandomPowerUpChance();
+		if (powerUpType == null && powerUpChance > 0f && MathUtils.randomBoolean(powerUpChance)) {
+			powerUpType = PowerUpType.getWeightedRandom();
+		}
+
 		if (powerUpType != null) {
 			((PlayState) state).powerUps.add(powerUpType.createInstance((PlayState) state, this));
 		}

core/src/com/me/brickbuster/layout/FileLayout.java

@@ -1,30 +1,26 @@
 package com.me.brickbuster.layout;
 
-import com.badlogic.gdx.files.FileHandle;
 import com.badlogic.gdx.utils.Array;
-import com.badlogic.gdx.utils.Json;
 import com.me.brickbuster.entity.Brick;
+import com.me.brickbuster.state.FieldState;
 import com.me.brickbuster.state.PlayState;
 
 public class FileLayout implements BrickLayout {
 
-	private static final Json JSON = new Json();
+	private FieldState state;
-
+	private LevelJsonTemplate template;
-	private PlayState state;
 	private Array<Brick> bricks;
-	private FileHandle file;
 
-	public FileLayout(PlayState state, FileHandle file) {
+	public FileLayout(FieldState state, LevelJsonTemplate template) {
 		this.state = state;
-		this.file = file;
+		this.template = template;
 	}
 
 	@Override
 	public void initialize() {
 		bricks = new Array<Brick>();
 
-		LevelJsonTemplate level = JSON.fromJson(LevelJsonTemplate.class, file);
+		for (LevelJsonTemplate.BrickJsonTemplate brick : template.bricks) {
-		for (LevelJsonTemplate.BrickJsonTemplate brick : level.bricks) {
 			final float x = PlayState.EDGE_PADDING + Brick.BRICK_WIDTH/2 + brick.col * Brick.BRICK_WIDTH;
 			final float y = PlayState.EDGE_PADDING + Brick.BRICK_HEIGHT/2 + brick.row * Brick.BRICK_HEIGHT;
 

core/src/com/me/brickbuster/layout/FileLevelLoader.java

@@ -2,14 +2,19 @@ package com.me.brickbuster.layout;
 
 import com.badlogic.gdx.Gdx;
 import com.badlogic.gdx.files.FileHandle;
+import com.badlogic.gdx.graphics.Texture;
+import com.badlogic.gdx.utils.Json;
+import com.me.brickbuster.state.FieldState;
 import com.me.brickbuster.state.PlayState;
 
 public class FileLevelLoader implements LevelLoader {
 
-	private PlayState state;
+	private static final Json JSON = new Json();
+
+	private FieldState state;
 	private int level = 1;
 
-	public FileLevelLoader(PlayState state) {
+	public FileLevelLoader(FieldState state) {
 		this.state = state;
 	}
 
@@ -17,8 +22,15 @@ public class FileLevelLoader implements LevelLoader {
 	public Level getNextLevel() {
 		FileHandle file = Gdx.files.internal("levels/level_" + level + ".json");
 		if (file.exists()) {
+			LevelJsonTemplate template = JSON.fromJson(LevelJsonTemplate.class, file);
+
+			Texture background = null;
+			if (template.backgroundFile != null && !"".equals(template.backgroundFile)) {
+				background = new Texture(Gdx.files.internal(template.backgroundFile));
+			}
+
 			level++;
-			return new Level(new FileLayout(state, file), null, null);
+			return new Level(new FileLayout(state, template), background, template.randomPowerUpChance);
 		}
 		return null;
 	}

core/src/com/me/brickbuster/layout/Level.java

@@ -6,16 +6,16 @@ public class Level {
 
 	private final BrickLayout layout;
 	private final Texture background;
-	private final Texture border;
+	private final float randomPowerUpChance;
 
 	public Level(BrickLayout layout) {
-		this(layout, null, null);
+		this(layout, null, 0f);
 	}
 
-	public Level(BrickLayout layout, Texture background, Texture border) {
+	public Level(BrickLayout layout, Texture background, float randomPowerUpChance) {
 		this.layout = layout;
 		this.background = background;
-		this.border = border;
+		this.randomPowerUpChance = randomPowerUpChance;
 	}
 
 	public BrickLayout getLayout() {
@@ -26,8 +26,8 @@ public class Level {
 		return background;
 	}
 
-	public Texture getBorder() {
+	public float getRandomPowerUpChance() {
-		return border;
+		return randomPowerUpChance;
 	}
 
 }

core/src/com/me/brickbuster/layout/LevelJsonTemplate.java

@@ -9,7 +9,7 @@ import java.util.List;
 public class LevelJsonTemplate {
 
 	public String backgroundFile;
-	public String borderFile;
+	public float randomPowerUpChance;
 	public List<BrickJsonTemplate> bricks;
 
 	public static class BrickJsonTemplate {