From 511a499c7d34ce28600121cf030387eb4b509530 Mon Sep 17 00:00:00 2001
From: Armaan Bhojwani <me@armaanb.net>
Date: Sat, 15 May 2021 20:23:21 -0400
Subject: [PATCH] Reflect ball depending on where its hit

---
 pong.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/pong.c b/pong.c
index 1363ae5..4bda2a7 100644
--- a/pong.c
+++ b/pong.c
@@ -21,6 +21,14 @@ randslope(void)
 	return (rand() % (high - low + 1)) + low;
 }
 
+double
+randspeed(void)
+{
+	const int low = 1;
+	const int high = 2;
+	return ((rand() % (high - low + 1)) + low) / 100.0;
+}
+
 int
 randsign(void)
 {
@@ -30,15 +38,15 @@ randsign(void)
 int
 main(void) {
 	srand((unsigned int)time(NULL));
-	int x, y, aoff = 0, boff = 0;
+	int aoff = 0, boff = 0;
 	int max_y, max_x;
 	int max_y_new = 0, max_x_new = 0;
 	int pad_h = 5;
 	int a_score = 0, b_score = 0;
 	int slope_x = randslope();
 	int index_dir = randsign();
-	int direction = 1;
-	double speed = 0.02;
+	int direction = randsign();
+	double speed = randspeed();
 	struct timeval start, stop;
 
 	// Initialize curses
@@ -49,8 +57,8 @@ main(void) {
 	getmaxyx(stdscr, max_y, max_x);
 	--max_x;
 	--max_y;
-	int index = slope_x*max_y/2;
-	x = max_x/2;
+	int y = max_y/2;
+	int x = max_x/2;
 
 	gettimeofday(&start, NULL);
 	while(1) {
@@ -110,16 +118,23 @@ main(void) {
 		if ((double)(stop.tv_usec - start.tv_usec) / 1000000 +
 				(double)(stop.tv_sec - start.tv_sec) > speed) {
 			gettimeofday(&start, NULL);
-			index += index_dir;
 			mvprintw(y, x, " ");
 			x += direction;
-			y = index / slope_x;
+			if (x % slope_x == 0) y += index_dir;
 			mvprintw(y, x, "o");
 		}
 
 		if ((x >= max_x - 1 && y >= boff && y <= boff + pad_h) ||
 				(x <= 1 && y >= aoff && y <= aoff + pad_h)) {
 			// Ball hits paddle
+
+			/* Find the distance that the ball hits from the center of the padel and
+				 accordingly adjust ball path */
+			int poff = (x <= 1) ? aoff : boff;
+			double fromc = fabs(0.5 * (poff + 0.5 * pad_h - y));
+			slope_x *= (slope_x < 20) ? 1 : (int) ((double) slope_x / fromc);
+			slope_x += 1;
+
 			direction *= -1;
 			x += direction;
 			speed *= 0.9;
@@ -131,16 +146,15 @@ main(void) {
 				a_score += 1;
 			}
 			x = max_x/2;
-			index = slope_x*max_y/2;
 			slope_x = randslope();
 			index_dir = randsign();
-			speed = 0.02;
+			speed = randspeed();
 			sleep(1);
 		} else if (y == 0 || y == max_y) {
 			// Ball hits top or bottom wall
 			index_dir *= -1;
 			mvprintw(y, x, " ");
-			y = max_y - 1;
+			y = (y == max_y) ? max_y - 1 : 1;
 		}
 	}
 }
-- 
2.39.2