Don't allow paddles to go off of screen

[pong.git] / pong.c

diff --git a/pong.c b/pong.c
index 83d3647ec2b3a2977cd24e541b6f1dda73b212e4..cea4d2ad555187b3155b73e8ea910a5d80441cf3 100644 (file)
--- a/pong.c
+++ b/pong.c
@@ -4,6 +4,7 @@
 #include <unistd.h>
 #include <sys/time.h>
 #include <time.h>
+#include <math.h>
 
 int
 die(int code)
@@ -12,18 +13,40 @@ die(int code)
        exit(code);
 }
 
+int
+randslope(void)
+{
+       const int low = 2;
+       const int high = 10;
+       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)
+{
+       return pow(-1, rand());
+}
+
 int
 main(void) {
-       int x, y, aoff = 0, boff = 0;
+       srand((unsigned int)time(NULL));
+       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 = 8;
-       int slope_y = 1;
-       int index_dir = 1;
-       int direction = 1;
-       double speed = 0.015;
+       int slope_x = randslope();
+       int index_dir = randsign();
+       int direction = randsign();
+       double speed = randspeed();
        struct timeval start, stop;
 
        // Initialize curses
@@ -34,8 +57,8 @@ main(void) {
        getmaxyx(stdscr, max_y, max_x);
        --max_x;
        --max_y;
-       int index = (max_y/2)*(slope_x/slope_y);
-       x = max_x/2;
+       int y = max_y/2;
+       int x = max_x/2;
 
        gettimeofday(&start, NULL);
        while(1) {
@@ -55,13 +78,13 @@ main(void) {
                if (key == 'q') {
                        die(0);
                } else if (key == 'k') {
-                       boff += 2;
+                       if (boff < max_y - pad_h) boff += 1;
                } else if (key == 'i') {
-                       boff -= 2;
+                       if (boff > 0) boff -= 1;
                } else if (key == 's') {
-                       aoff += 2;
+                       if (aoff < max_y - pad_h) aoff += 1;
                } else if (key == 'w') {
-                       aoff -= 2;
+                       if (aoff > 0) aoff -= 1;
                }
 
                // Clear screen
@@ -95,38 +118,43 @@ 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 = slope_y * index / slope_x;
+                       if (x % slope_x == 0) y += index_dir;
                        mvprintw(y, x, "o");
                }
 
-               // Check if touching paddle or edges
-               if (x >= max_x - 1) {
-                       if (y >= boff && y <= boff + pad_h) {
-                               direction *= -1;
-                               x += direction;
+               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;
+               } else if (x >= max_x - 1 || x <= 1) {
+                       // Ball goes out of bounds
+                       if (x <=1) {
+                               b_score += 1;
                        } else {
                                a_score += 1;
-                               x = max_x/2;
-                               index = (max_y/2)*(slope_x/slope_y);
-                               speed /= 0.8;
-                               sleep(1);
-                       }
-               } else if (x <= 1) {
-                       if (y >= aoff && y <= aoff + pad_h) {
-                               direction *= -1;
-                               x += direction;
-                       } else {
-                               b_score += 1;
-                               x = max_x/2;
-                               index = (max_y/2)*(slope_x/slope_y);
-                               speed /= 0.8;
-                               sleep(1);
                        }
+                       x = max_x/2;
+                       slope_x = randslope();
+                       index_dir = randsign();
+                       speed = randspeed();
+                       sleep(1);
                } else if (y == 0 || y == max_y) {
+                       // Ball hits top or bottom wall
                        index_dir *= -1;
+                       mvprintw(y, x, " ");
+                       y = (y == max_y) ? max_y - 1 : 1;
                }
        }
 }