I'm trying to make a basic
space invaders clone in allegro 5, I've got my game set up, basic events and such, here is
the code:
#include <allegro5/allegro.h>
#include <allegro5/allegro_image.h>
#include <allegro5/allegro_primitives.h>
#include <allegro5/allegro_font.h>
#include <allegro5/allegro_ttf.h>
#include "Entity.h"
// GLOBALS ==========================================
const int width = 500;
const int height = 500;
const int imgsize = 3;
bool key[5] = {false, false, false, false, false};
bool running = true;
bool draw = true;
// FUNCTIONS ========================================
void initSpaceship(Spaceship &ship);
void moveSpaceshipRight(Spaceship &ship);
void moveSpaceshipLeft(Spaceship &ship);
void initInvader(Invader &invader);
void moveInvaderRight(Invader &invader);
void moveInvaderLeft(Invader &invader);
void initBullet(Bullet &bullet);
void fireBullet();
void doCollision();
void updateInvaders();
void drawText();
enum key_t { UP, DOWN, LEFT, RIGHT,
SPACE };
enum source_t { INVADER, DEFENDER };
int main(void)
{
if(!al_init())
{ return -1; }
Spaceship ship;
Invader invader;
Bullet bullet;
al_init_image_addon();
al_install_keyboard();
al_init_font_addon();
al_init_ttf_addon();
ALLEGRO_DISPLAY *display = al_create_display(width, height);
ALLEGRO_EVENT_QUEUE *event_queue = al_create_event_queue();
ALLEGRO_TIMER *timer = al_create_timer(1.0 / 60);
ALLEGRO_BITMAP *images[imgsize];
ALLEGRO_FONT *font1 = al_load_font("arial.ttf", 20, 0);
al_register_event_source(event_queue, al_get_keyboard_event_source());
al_register_event_source(event_queue, al_get_display_event_source(display));
al_register_event_source(event_queue, al_get_timer_event_source(timer));
images[0] = al_load_bitmap("defender.bmp");
images[1] = al_load_bitmap("invader.bmp");
images[2] = al_load_bitmap("explosion.bmp");
al_convert_mask_to_alpha(images[0], al_map_rgb(0, 0, 0));
al_convert_mask_to_alpha(images[1], al_map_rgb(0, 0, 0));
al_convert_mask_to_alpha(images[2], al_map_rgb(0, 0, 0));
initSpaceship(ship);
initBullet(bullet);
initInvader(invader);
al_start_timer(timer);
while(running)
{
ALLEGRO_EVENT ev;
al_wait_for_event(event_queue, &ev);
if(ev.type == ALLEGRO_EVENT_TIMER)
{
draw = true;
if(key[RIGHT] == true)
moveSpaceshipRight(ship);
if(key[LEFT] == true)
moveSpaceshipLeft(ship);
}
else if(ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE)
running = false;
else if(ev.type == ALLEGRO_EVENT_KEY_DOWN)
{
switch(ev.keyboard.keycode)
{
case ALLEGRO_KEY_ESCAPE:
running = false;
break;
case ALLEGRO_KEY_LEFT:
key[LEFT] = true;
break;
case ALLEGRO_KEY_RIGHT:
key[RIGHT] = true;
break;
case ALLEGRO_KEY_SPACE:
key[SPACE] = true;
break;
}
}
else if(ev.type == ALLEGRO_KEY_UP)
{
switch(ev.keyboard.keycode)
{
case ALLEGRO_KEY_LEFT:
key[LEFT] = false;
break;
case ALLEGRO_KEY_RIGHT:
key[RIGHT] = false;
break;
case ALLEGRO_KEY_SPACE:
key[SPACE] = false;
break;
}
}
if(draw && al_is_event_queue_empty(event_queue))
{
draw = false;
al_draw_bitmap(images[0], ship.pos_x, ship.pos_y, 0);
al_flip_display();
al_clear_to_color(al_map_rgb(0, 0, 0));
}
}
al_destroy_font(font1);
al_destroy_event_queue(event_queue);
al_destroy_timer(timer);
for(int i = 0; i < imgsize; i++)
al_destroy_bitmap(images[i]);
al_destroy_display(display);
}
// FUNCTION LOGIC ======================================
void initSpaceship(Spaceship &ship)
{
ship.lives = 3;
ship.speed = 2;
ship.pos_x = width / 2;
ship.pos_y = height - 20;
}
void initInvader(Invader &invader)
{
invader.health = 100;
invader.count = 40;
invader.speed = 0.5;
invader.pos_x = 300;
invader.pos_y = 300;
}
void initBullet(Bullet &bullet)
{
bullet.speed = 10;
}
void moveSpaceshipRight(Spaceship &ship)
{
ship.pos_x += ship.speed;
if(ship.pos_x >= width)
ship.pos_x = width-30;
}
void moveSpaceshipLeft(Spaceship &ship)
{
ship.pos_x -= ship.speed;
if(ship.pos_x <= 0)
ship.pos_x = 0+30;
}
However it's not behaving
the way I want it to behave, in fact
the behavior for
the ship movement is un-normal. Basically I specified that
the ship only moves when
the right/left key is down, however
the ship is moving constantly to
the direction of
the key pressed, it never stops although it should only move while my key is down. Even more weird behavior, when I press
the opposite key
the ship completely stops no matter what else I press.
What's wrong with
the code? Why does
the ship move constantly even after I specified it only moves when a key is down?
