Implement y-velocity, and added other minor changes

pong.c

@@ -1,9 +1,11 @@
 #include <stdio.h>
+#include <stdlib.h>
 #include <allegro5/allegro.h>
 #include <allegro5/allegro_font.h>
 #include <allegro5/allegro_ttf.h>
 #include <allegro5/allegro_image.h>
 #include <allegro5/allegro_primitives.h>
+#include <math.h>
 
 #define WIN_WIDTH 1000
 #define WIN_HEIGHT 600
@@ -32,7 +34,8 @@ int main(int argc, char** argv) {
 	ALLEGRO_COLOR black = al_map_rgba(0,0,0,255);
 	ALLEGRO_COLOR white = al_map_rgba(255,255,255,255);
 	ALLEGRO_EVENT event;
-	bool running = true;
+	bool running = false;
+	srand(time(NULL)); // Seed for RNG
 
 	float width = 25;  // Width and height of paddles
 	float height = 150;
@@ -43,11 +46,14 @@ int main(int argc, char** argv) {
 	float velocity_1 = 0;  // Vertical velocity of first paddle
 	float velocity_2 = 0;  // Vertical velocity of second paddle
 
-	float circ_x = WIN_WIDTH / 2; // Center coordinates of ball
-	float circ_y = WIN_HEIGHT / 2;
-	float circ_rad = 10;  // Radius of ball
-	float circ_vel_x = 5; // Horizontal velocity of ball
-	float circ_vel_y = 0; // Vertical velocity of ball
+	float circ_x = 25; // Center coordinates of ball
+	float circ_y = 25;
+	float circ_rad = 15;  // Radius of ball
+	float ball_speed = sqrt(72); // Pythagorean distance travelled by ball in one main-loop iteration
+	float circ_vel_x = (float)(rand())/(float)(RAND_MAX / 3) + 4.0; // Horizontal velocity of ball (Randomly generated, 4 to 7) - borrowed from https://stackoverflow.com/a/13409133
+	printf("%f\n",circ_vel_x);
+	float circ_vel_y = sqrt(pow(ball_speed,2) - pow(circ_vel_x,2)); // Vertical velocity of ball - Subtract X velocity from hypotenuse / ball_speed
+	printf("%f\n",circ_vel_y);
 
 	al_clear_to_color(black);
 	al_draw_filled_rectangle(start_x_1, start_y_1, start_x_1 + width, start_y_1 + height, white);
@@ -55,6 +61,12 @@ int main(int argc, char** argv) {
 	al_draw_filled_circle(circ_x, circ_y, circ_rad, white);
 	al_flip_display();
 
+	do {
+		al_wait_for_event(queue, &event);
+	} while (!(event.type == ALLEGRO_EVENT_KEY_DOWN && event.keyboard.keycode == ALLEGRO_KEY_SPACE));
+
+	running = true;
+
 	while (running) {
 		// Code borrowed from: https://stackoverflow.com/a/30078011
 
@@ -68,7 +80,7 @@ int main(int argc, char** argv) {
 						break;
 					case ALLEGRO_KEY_S:
 						velocity_1 += 5;
-						break; 
+						break;
 					case ALLEGRO_KEY_UP:
 						velocity_2 -= 5;
 						break;
@@ -107,12 +119,6 @@ int main(int argc, char** argv) {
 		((velocity_2 < 0 && start_y_2  > 0) || (velocity_2 > 0 && start_y_2 + height < WIN_HEIGHT)) && (start_y_2 += velocity_2);
 		circ_x += circ_vel_x;
 		circ_y += circ_vel_y;
-		
-		//Redraw shapes
-		al_draw_filled_rectangle(start_x_1, start_y_1, start_x_1 + width, start_y_1 + height + velocity_1, white);		
-		al_draw_filled_rectangle(start_x_2, start_y_2, start_x_2 + width, start_y_2 + height + velocity_2, white);		
-		al_draw_filled_circle(circ_x, circ_y, circ_rad, white);
-		al_flip_display();
 
 		if (circ_x + circ_rad >= WIN_WIDTH - 10 - width) { // FOR PADDLE 2: If the circle has reached the point where the paddle would be...
 			if (circ_y > start_y_2 && circ_y < start_y_2 + height) { // If the circle is touching the paddle...
@@ -120,15 +126,27 @@ int main(int argc, char** argv) {
 			}
 		} else if (circ_x - circ_rad <= 10 + width) { // FOR PADDLE 1
 			if (circ_y > start_y_1 && circ_y < start_y_1 + height) {
-				circ_vel_x =- circ_vel_x;
+				circ_vel_x = -circ_vel_x;
 			}
 		}
 
+		if ((circ_y + circ_rad >= WIN_HEIGHT) || (circ_y - circ_rad <= 0)) {
+			circ_vel_y = -circ_vel_y;
+		}
+
+
+
+		//Redraw shapes
+		al_draw_filled_rectangle(start_x_1, start_y_1, start_x_1 + width, start_y_1 + height + velocity_1, white);
+		al_draw_filled_rectangle(start_x_2, start_y_2, start_x_2 + width, start_y_2 + height + velocity_2, white);
+		al_draw_filled_circle(circ_x, circ_y, circ_rad, white);
+		al_flip_display();
+
 	}
 
 //	Clean up
 	al_destroy_display(disp);
-	al_destroy_event_queue(queue);	
-	
+	al_destroy_event_queue(queue);
+
 	return 0;
 }