From f08b0d5b75304bdb2d997fcafe9596a55ef781d0 Mon Sep 17 00:00:00 2001
From: Joe <dev@joea.co.uk>
Date: Sun, 10 Dec 2017 20:39:34 +0000
Subject: [PATCH] Added some comments and changed X velocity post
 paddle-collision to be proportional to the relative position of the ball and
 paddle

---
 breakout/breakout.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/breakout/breakout.c b/breakout/breakout.c
index 0bc1736..baff5f7 100644
--- a/breakout/breakout.c
+++ b/breakout/breakout.c
@@ -234,24 +234,25 @@ int main(void) {
 }
 
 void updateBall(double *ballX, double *ballY, double *ballVX, double *ballVY, double paddleX, int paddleWidth, int winWidth, int winHeight) {
-  double ballNX = *ballX + *ballVX;
+  double ballNX = *ballX + *ballVX; // Calculates the position of the ball on the next step
   double ballNY = *ballY + *ballVY;
   double paddleRX = paddleX - (double)(winWidth / 2);
   double paddleRY = 20 - (double)(winHeight / 2);
 
-  if (ballNX > paddleRX && ballNY<paddleRY) {
-    if (ballNX < paddleRX + paddleWidth) {
+  if (ballNX > paddleRX && ballNY<paddleRY) { // If to the right or below the top left corner of paddle
+    if (ballNX < paddleRX + (double)paddleWidth) { // ...and to the left of the right side of the paddle (i.e. about to go inside inside the paddle)
       *ballVY *= -1.0;
+      *ballVX = ((ballNX - paddleRX - (double)(paddleWidth/2))/((double)paddleWidth/2))*0.5; // Sets X velocity to be proportional to the relative position of the ball and the paddle on collision
     }
   }
 
-  if (ballNX > winWidth / 2 || ballNX < (-1.0*winWidth/2)) {
+  if (ballNX > winWidth / 2 || ballNX < (-1.0*winWidth/2)) { // Collision with walls
     *ballVX *= -1.0;
   }
-  if (ballNY > winHeight / 2) {
+  if (ballNY > winHeight / 2) { // Collision with ceiling
     *ballVY *= -1.0;
   }
-  if (ballNY < (-1.0*winHeight/2)) {
+  if (ballNY < (-1.0*winHeight/2)) { // Collision with floor
     *ballX = 0;
     *ballY = 0;
     *ballVX = -0.1;