OpenEuphoria

The modules of allegro

Modules is probably a bit of a misnomer, as there aren't individual modules, but we can group then together to get a set of functions to create a game. Look at http://www.connellybarnes.com/documents/quick_reference.html for a quick reference to several of them, and the allegro help file in the downloads.

The function groups can be broken down to

• Video and graphic routines
• Input routines
• Sound and music routines

Which basically sums up what you need to do for a game.

What can you do with modules? Anything you want! You should always do some things to set allegro up, and close it down properly, but apart from that have a look through the examples for what's possible.

What you should do everytime.

ret = allegro_init()                                             --initialise allegro            
ret = install_keyboard()                                         --if you want to use the keyboard routines  
                                                                 --to read the keyboard 
ret = install_timer()                                            --if you want to use the timer functions, but they are a 
                                                                 --unreliable (at the moment) 
ret = install_mouse()                                            --if you want to use the mouse 
ret = install_sound(DIGI_AUTODETECT, MIDI_NONE, "")              --if you want to use allegro's sound functions 
ret = set_gfx_mode(GFX_AUTODETECT_WINDOWED, 320, 200, 0, 0)      --set a video mode 
 
--each of these returns -1 if unsuccessful, so you could test for success at this stage 
 
--some monitors / graphics cards can't cope with allegro's fullscreen graphics modes, so what I do is 
ret = set_gfx_mode(GFX_AUTODETECT_FULLSCREEN, 640,480, 0, 0) 
if ret = -1 then 
    --switch to a safe mode instead 
    ret = set_gfx_mode(GFX_SAFE, 640, 480, 0, 0) 
end if 
 

and at the end

ellegro_exit()                                                   --will close allegro cleanly 

The available graphics modes are GFX_TEXT GFX_AUTODETECT GFX_AUTODETECT_FULLSCREEN GFX_AUTODETECT_WINDOWED GFX_SAFE GFX_DIRECTX_WIN

and the available resolutions are 320*240, 640*480, 1025*768 - this may seem restrictive for modern computers, but for what allegro does, it is more than adequate.

You do not need to initialise the jouystick - we aren't using allegro's joystick functions, just include joy .ew, create a sequence, and use the global variables global integer XPOS = 1, YPOS = 2, ZPOS = 3, RPOS = 4, UPOS = 5, VPOS = 6, BUTTONS = 7, POV = 8 to reference it - see joytest for details.

If you want to read mp3, then you have to use fmod, include the fmod.ew wrapper - like allegro you need to initialise it - I will add another page for this.

Once you've done this, you can get on with playing samples, loading sprites and bitmap, and blitting them left right and centre.

• Allegro home