Question

I’m new in Allegro 5, I’ve written some code with the few tutorials there are so far, but I cannot get the joystick sticks input.

Here the code, it is just two bars moving perpendicularly(and a very lazy approach, just swapped the x an y coordinates on the second bar).

#pragma comment (lib,"allegro-5.0.2-monolith-md-debug.lib")
#include <stdio.h>
#include <string>
#include <iostream>
#include <allegro5/allegro.h>
#include <allegro5/allegro_font.h>
#include <allegro5/allegro_ttf.h>

#define FPS 0xFF
#define SCREEN_W 1000
#define SCREEN_H 750
#define BAR_W 75
#define BAR_H 10

enum KEYS
{
    KEY_LEFT, KEY_RIGHT
};

int main(int argc, char **argv)
{
    ALLEGRO_DISPLAY *display = NULL;
    ALLEGRO_EVENT_QUEUE *event_queue = NULL;
    ALLEGRO_JOYSTICK *joystick = NULL;
    ALLEGRO_TIMER *timer = NULL;
    ALLEGRO_BITMAP *bouncer = NULL;
    float bouncer_x = SCREEN_W / 2.0 - BAR_W / 2.0;
    float bouncer_y = SCREEN_H - BAR_H;
    bool key[2] = {false, false};
    bool redraw = true;
    bool doexit = false;

    if(!al_init())
    {
        fprintf(stderr, "failed to initialize allegro!\n");
        return -1;
    }

    if(!al_install_keyboard())
    {
        fprintf(stderr, "failed to initialize the keyboard!\n");
        return -1;
    }

    if(!al_install_joystick())
    {
        fprintf(stderr, "failed to initialize the joystick!\n");
    }
    al_reconfigure_joysticks();
    joystick=al_get_joystick(al_get_num_joysticks()-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;
    }

    bouncer = al_create_bitmap(BAR_W, BAR_H);
    if(!bouncer)
    {
        fprintf(stderr, "failed to create bouncer bitmap!\n");
        al_destroy_display(display);
        al_destroy_timer(timer);
        return -1;
    }

    al_set_target_bitmap(bouncer);
    al_clear_to_color(al_map_rgb(0, 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_bitmap(bouncer);
        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_register_event_source(event_queue, al_get_keyboard_event_source());
    al_register_event_source(event_queue, al_get_joystick_event_source());
    al_clear_to_color(al_map_rgb(0,0,0));

    al_flip_display();
    al_start_timer(timer);

    while(!doexit)
    {
        ALLEGRO_EVENT ev;
        al_wait_for_event(event_queue, &ev);


        if(ev.type == ALLEGRO_EVENT_TIMER)
        {

            if(key[KEY_LEFT] && bouncer_x >= 2.0)
                bouncer_x -= 2.0;

            if(key[KEY_RIGHT] && bouncer_x <= SCREEN_W - BAR_W - 2.0)
                bouncer_x += 2.0;

            redraw = true;
        }

        else if(ev.type == ALLEGRO_EVENT_JOYSTICK_AXIS
                && ev.joystick.stick == 0
                && ev.joystick.axis == 0)
        {        
            float joypos=ev.joystick.pos;

            if(joypos<0 && bouncer_x >= 2.0)
                bouncer_x-=joypos;

            if(joypos>0 && bouncer_x <= SCREEN_W - BAR_W - 2.0)
                bouncer_x+=joypos;

            if(joypos=0)
                bouncer_x=SCREEN_W/2;
        }

        else if(ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE)
            break;

        else if(ev.type == ALLEGRO_EVENT_KEY_DOWN)
        {
            switch(ev.keyboard.keycode)
            {
            case ALLEGRO_KEY_LEFT:
                key[KEY_LEFT] = true;
                break;

            case ALLEGRO_KEY_RIGHT:
                key[KEY_RIGHT] = true;
                break;
            }
        }
        else if(ev.type == ALLEGRO_EVENT_KEY_UP)
        {
            switch(ev.keyboard.keycode)
            {
            case ALLEGRO_KEY_LEFT: 
                key[KEY_LEFT] = false;
                break;

            case ALLEGRO_KEY_RIGHT:
                key[KEY_RIGHT] = false;
                break;

            case ALLEGRO_KEY_ESCAPE:
                doexit = true;
                break;
            }
        }

        if(redraw && al_is_event_queue_empty(event_queue))
        {
            std::string str=al_get_joystick_name(joystick);
            redraw = false;

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

            al_draw_bitmap(bouncer, bouncer_x, bouncer_y, 0);
            al_draw_bitmap(bouncer, bouncer_y, bouncer_x, 0);

            std::cout << ev.joystick.pos << " ";
            std::cout << str << " ";
            std::cout << al_get_joystick_active(joystick) << std::endl;

            al_flip_display();
        }
    }

    al_destroy_bitmap(bouncer);
    al_destroy_timer(timer);
    al_destroy_display(display);
    al_destroy_event_queue(event_queue);

    return 0;
}

Now, the trouble: ev.joystick.pos has a relatively static value (viewed trough MSVC2010 debugger), no matter if I have all the axis of my joystick at the max position.

Also, I don’t know how to get the value of an specific axis of an specific stick. I managed to get the bar move only when an specific axis and stick changes, but not “how much” it changes.

Thanks in advance.

Answer 1

I can’t see what you’re doing wrong, but I got the controller working in my game, so maybe my code will shed some insight. By the way, I’m using an Xbox 360 controller. Actually, I’m using a GameStop brand 360 controller, so it’s not technically official. Anyway, here’s my relevant code (the full source is a monster):

    if(ev.type == ALLEGRO_EVENT_JOYSTICK_AXIS){
        if(ev.type == ALLEGRO_EVENT_JOYSTICK_AXIS){
        if(ev.joystick.stick == 0){ //float joys[3][2]
            joys[ev.joystick.stick][ev.joystick.axis] = ev.joystick.pos;
        }
     }


    void SetPosition(){

    int leftStick = 0;
    int rightStick = 1;
    int dPad = 2;

    int x = 0;
    int y = 1;
    int z = 2;

    bitmapX += joys[leftStick][x];
    bitmapY += joys[leftStick][y];
    }