From 79f4334cd7b4b3bed94691339e1dc09224c930eb Mon Sep 17 00:00:00 2001
From: Matt Low <mattjlow94@gmail.com>
Date: Sun, 11 Nov 2018 15:07:29 +0400
Subject: [PATCH] Add screen edge reflection.

---
 core/src/com/me/brickbuster/BrickBuster.java |  6 ++++++
 core/src/com/me/brickbuster/Utils.java       | 12 ++++++++++++
 core/src/com/me/brickbuster/entity/Ball.java | 18 +++++++++++++++---
 3 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 core/src/com/me/brickbuster/Utils.java

diff --git a/core/src/com/me/brickbuster/BrickBuster.java b/core/src/com/me/brickbuster/BrickBuster.java
index a438c22..f284d8c 100644
--- a/core/src/com/me/brickbuster/BrickBuster.java
+++ b/core/src/com/me/brickbuster/BrickBuster.java
@@ -3,6 +3,7 @@ package com.me.brickbuster;
 import com.badlogic.gdx.ApplicationAdapter;
 import com.badlogic.gdx.Gdx;
 import com.badlogic.gdx.graphics.GL20;
+import com.badlogic.gdx.math.Vector2;
 import com.me.brickbuster.entity.Ball;
 import com.me.brickbuster.entity.Block;
 import com.me.brickbuster.entity.Paddle;
@@ -15,6 +16,11 @@ public class BrickBuster extends ApplicationAdapter {
 	public static final int HEIGHT = 600;
 	public static final String TITLE = "Brick Buster";
 
+	public static final Vector2 RIGHT_EDGE = new Vector2(0, 1);
+	public static final Vector2 TOP_EDGE = new Vector2(-1, 0);
+	public static final Vector2 LEFT_EDGE = new Vector2(0, -1);
+	public static final Vector2 BOTTOM_EDGE = new Vector2(1, 0);
+
 	Ball ball;
 	Paddle paddle;
 	ArrayList<Block> blocks;
diff --git a/core/src/com/me/brickbuster/Utils.java b/core/src/com/me/brickbuster/Utils.java
new file mode 100644
index 0000000..0f950b6
--- /dev/null
+++ b/core/src/com/me/brickbuster/Utils.java
@@ -0,0 +1,12 @@
+package com.me.brickbuster;
+
+import com.badlogic.gdx.math.Vector2;
+
+public class Utils {
+
+	public static Vector2 reflect(Vector2 incoming, Vector2 surface) {
+		Vector2 normal = new Vector2(-surface.y, surface.x);
+		return incoming.sub(normal.scl(normal.dot(incoming) * 2));
+	}
+
+}
diff --git a/core/src/com/me/brickbuster/entity/Ball.java b/core/src/com/me/brickbuster/entity/Ball.java
index 74b35d0..c23af4b 100644
--- a/core/src/com/me/brickbuster/entity/Ball.java
+++ b/core/src/com/me/brickbuster/entity/Ball.java
@@ -5,6 +5,7 @@ import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
 import com.badlogic.gdx.math.MathUtils;
 import com.badlogic.gdx.math.Vector2;
 import com.me.brickbuster.BrickBuster;
+import com.me.brickbuster.Utils;
 
 public class Ball extends Entity {
 
@@ -31,11 +32,22 @@ public class Ball extends Entity {
 		if (!getBrickBuster().isPlaying()) {
 			return;
 		}
+
+		int newX = getX() + (int) (direction.x * speed);
+		int newY = getY() + (int) (direction.y * speed);
+
+		if (newX + RADIUS > BrickBuster.WIDTH) {
+			Utils.reflect(direction, BrickBuster.RIGHT_EDGE);
+		} else if (newY + RADIUS > BrickBuster.HEIGHT) {
+			Utils.reflect(direction, BrickBuster.TOP_EDGE);
+		} else if (newX - RADIUS < 0) {
+			Utils.reflect(direction, BrickBuster.LEFT_EDGE);
+		} else if (newY - RADIUS < 0) {
+			Utils.reflect(direction, BrickBuster.BOTTOM_EDGE);
+		}
+
 		setX(getX() + (int) (direction.x * speed));
 		setY(getY() + (int) (direction.y * speed));
-		/*if (this.getX() + RADIUS < BrickBuster.WIDTH) {
-			this.setX(this.getX() + 1);
-		}*/
 	}
 
 	public void launch() {