Example Allegro Program

#include <stdio.h>
#include <allegro5/allegro.h>
#include <allegro5/allegro_primitives.h>
 
const float FPS = 60;
const int SCREEN_W = 1640;
const int SCREEN_H = 800;
const int BOUNCER_SIZE = 32;

int main(int argc, char **argv){
   ALLEGRO_DISPLAY *display = NULL;
   ALLEGRO_EVENT_QUEUE *event_queue = NULL;
   ALLEGRO_TIMER *timer = NULL;
   float bouncer_x = SCREEN_W / 2.0 - BOUNCER_SIZE / 2.0;
   float bouncer_y = SCREEN_H / 2.0 - BOUNCER_SIZE / 2.0;
   float bouncer_dx = -4.0, bouncer_dy = 4.0;
   bool redraw = true;
 
   if(!al_init()) {
      fprintf(stderr, "failed to initialize allegro!\n");
      return -1;
   }
 
   timer = al_create_timer(1.0 / FPS);
   if(!timer) {
      fprintf(stderr, "failed to create timer!\n");
      return -1;
   }
 
   display = al_create_display(SCREEN_W, SCREEN_H);
   if(!display) {
      fprintf(stderr, "failed to create display!\n");
      al_destroy_timer(timer);
      return -1;
   }

   al_clear_to_color(al_map_rgb(255, 0, 255));

   al_set_target_bitmap(al_get_backbuffer(display));
 
   event_queue = al_create_event_queue();
   if(!event_queue) {
      fprintf(stderr, "failed to create event_queue!\n");
      al_destroy_display(display);
      al_destroy_timer(timer);
      return -1;
   }
 
   al_register_event_source(event_queue, al_get_display_event_source(display));
 
   al_register_event_source(event_queue, al_get_timer_event_source(timer));
 
   al_clear_to_color(al_map_rgb(0,0,0));
 
   al_flip_display();
   

 
   al_start_timer(timer);
 
   while(1)
   {
      ALLEGRO_EVENT ev;
      al_wait_for_event(event_queue, &ev);
 
      if(ev.type == ALLEGRO_EVENT_TIMER) {
         if(bouncer_x < 0 || bouncer_x > SCREEN_W - BOUNCER_SIZE) {
            bouncer_dx = -bouncer_dx;
         }

         if(bouncer_y < 0 || bouncer_y > SCREEN_H - BOUNCER_SIZE) {
            bouncer_dy = -bouncer_dy;
         }

         bouncer_x += bouncer_dx;
         bouncer_y += bouncer_dy;
         

         
         redraw = true;
      }
      else if(ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE) {
         break;
      }
 
      if(redraw && al_is_event_queue_empty(event_queue)) {
         redraw = false;

         al_clear_to_color(al_map_rgb(0,0,0));

         al_draw_line(bouncer_x,  20,  800,  bouncer_y, al_map_rgb(255,0,0),20.0);
         al_draw_circle( bouncer_x, bouncer_y, 40 , al_map_rgb(0,0,255),3.0);
         al_flip_display();
      }
   }
 
   al_destroy_timer(timer);
   al_destroy_display(display);
   al_destroy_event_queue(event_queue);
 
   return 0;
}
Topic revision: r1 - 2017-10-09 - JimSkon
 
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