pong/pong.c

#include <stdio.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>

#define WIN_WIDTH 1000
#define WIN_HEIGHT 600

void alleg_init();

void alleg_init() {
	al_init();
	al_install_keyboard();
	al_install_mouse();
	al_init_image_addon();
	al_init_font_addon();
	al_init_ttf_addon();

	return;
}


int main(int argc, char** argv) {
//	Initialization

	alleg_init();
	ALLEGRO_DISPLAY* disp = al_create_display(WIN_WIDTH, WIN_HEIGHT);
	ALLEGRO_EVENT_QUEUE* queue  = al_create_event_queue();
	al_register_event_source(queue,al_get_keyboard_event_source());
	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 key_down_1 = false;
	bool key_down_2 = false;

	float width = 25;
	float height = 150;
	float start_x_1 = 10;
	float start_y_1 = 10;
	float start_x_2 = WIN_WIDTH - 10 - width;
	float start_y_2 = 10;
	float velocity_1 = 0;
	float velocity_2 = 0;

	al_clear_to_color(black);
	al_draw_filled_rectangle(start_x_1, start_y_1, start_x_1 + width, start_y_1 + height, white);
	al_draw_filled_rectangle(start_x_2, start_y_2, start_x_2 + width, start_y_2 + height, white);
	al_flip_display();

	while (running) {
		// Code borrowed from: https://stackoverflow.com/a/30078011

		while (!al_is_event_queue_empty(queue)) {
			al_wait_for_event(queue, &event);

			if (event.type == ALLEGRO_EVENT_KEY_DOWN) {
				switch (event.keyboard.keycode) {
					case ALLEGRO_KEY_W:
						velocity_1 -= 5;
						break;
					case ALLEGRO_KEY_S:
						velocity_1 += 5;
						break; 
					case ALLEGRO_KEY_UP:
						velocity_2 -= 5;
						break;
					case ALLEGRO_KEY_DOWN:
						velocity_2 += 5;
						break;

					case ALLEGRO_KEY_Q:
						running = false;
						break;
				}

			} else if (event.type == ALLEGRO_EVENT_KEY_UP) {
				switch (event.keyboard.keycode) {
					case ALLEGRO_KEY_W:
						velocity_1 += 5;
						break;
					case ALLEGRO_KEY_S:
						velocity_1 -= 5;
						break;
					case ALLEGRO_KEY_UP:
						velocity_2 += 5;
						break;
					case ALLEGRO_KEY_DOWN:
						velocity_2 -= 5;
						break;

				}
			}
		}

		al_clear_to_color(black);
		((velocity_1 < 0 && start_y_1  > 0) || (velocity_1 > 0 && start_y_1 + height < WIN_HEIGHT)) && (start_y_1 += velocity_1);
		((velocity_2 < 0 && start_y_2  > 0) || (velocity_2 > 0 && start_y_2 + height < WIN_HEIGHT)) && (start_y_2 += velocity_2);
		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_flip_display();
	}

//	Clean up
	al_destroy_display(disp);
	al_destroy_event_queue(queue);	
	
	return 0;
}