Graphics and 2D Games programming using RingAllegro¶

In this chapter we will learn how to use the allegro game programming library in our Ring applications.

We have the file gamelib.ring that load the DLL library that contains wrappers for the Allegro functions

Load "allegro.rh"
Loadlib("ring_allegro.dll")

The file gamelib.ring uses the Load instruction to execute the file allegro.rh which is a ring source code file contains constants to be used in our programs. Then using the function LoadLib() we can load the DLL library “ring_allegro.dll”.

To write portable code we can change the gamelib.ring to check the platform before loading the DLL/So file.

Drawing, Animation and Input¶

The next example uses the Allegro library for drawing, moving objects on the screen and getting input from the keyboard and the mouse.

Load "gamelib.ring"

al_init()
al_init_image_addon()

display = al_create_display(640,480)

al_show_native_message_box(display, "Hello", "Welcome",
                        "Using Allegro from the Ring programming language",
                        "", 0);

al_clear_to_color(al_map_rgb(0,0,255))

BOUNCER_SIZE = 40
bouncer_x = 10
bouncer_y = 20
bouncer = al_create_bitmap(BOUNCER_SIZE, BOUNCER_SIZE)
al_set_target_bitmap(bouncer)
al_clear_to_color(al_map_rgb(255,0,255))

for x = 1 to 30
        bouncer_x += x
        bouncer_y += x
        al_set_target_bitmap(al_get_backbuffer(display))
        al_clear_to_color(al_map_rgb(0,0,0))
        al_draw_bitmap(bouncer, bouncer_x, bouncer_y, 0)
        al_draw_bitmap(bouncer, 200+bouncer_x,200+ bouncer_y, 0)
        al_flip_display()
        al_rest(0.1)
next

al_clear_to_color(al_map_rgb(255,255,255))
image = al_load_bitmap("man2.jpg")
al_draw_bitmap(image,200,200,0)
al_flip_display()
al_rest(2)

event_queue = al_create_event_queue()
al_register_event_source(event_queue, al_get_display_event_source(display))

ev = al_new_allegro_event()
timeout = al_new_allegro_timeout()
al_init_timeout(timeout, 0.06)

FPS = 60
timer = al_create_timer(1.0 / FPS)
al_register_event_source(event_queue, al_get_timer_event_source(timer))
al_start_timer(timer)
redraw = true

SCREEN_W = 640
SCREEN_H = 480
BOUNCER_SIZE = 32
bouncer_x = SCREEN_W / 2.0 - BOUNCER_SIZE / 2.0
bouncer_y = SCREEN_H / 2.0 - BOUNCER_SIZE / 2.0
bouncer_dx = -4.0
bouncer_dy = 4.0

al_install_mouse()
al_register_event_source(event_queue, al_get_mouse_event_source())

al_install_keyboard()
al_register_event_source(event_queue, al_get_keyboard_event_source())

KEY_UP = 1
KEY_DOWN = 2
KEY_LEFT = 3
KEY_RIGHT = 4
Key = [false,false,false,false]

while true
        al_wait_for_event_until(event_queue, ev, timeout)
        switch al_get_allegro_event_type(ev)
        on ALLEGRO_EVENT_DISPLAY_CLOSE
                exit
        on ALLEGRO_EVENT_TIMER

                # Animation
                if bouncer_x < 0 or bouncer_x > SCREEN_W - BOUNCER_SIZE
                        bouncer_dx = -bouncer_dx
                ok

                if bouncer_y < 0 or bouncer_y > SCREEN_H - BOUNCER_SIZE
                        bouncer_dy = -bouncer_dy
                ok

                bouncer_x += bouncer_dx
                bouncer_y += bouncer_dy

                # Keyboard
                if key[KEY_UP] and bouncer_y >= 4.0
                        bouncer_y -= 4.0
                ok
                if key[KEY_DOWN] and bouncer_y <= SCREEN_H - BOUNCER_SIZE - 4.0
                        bouncer_y += 4.0
                ok
                if key[KEY_LEFT] and bouncer_x >= 4.0
                        bouncer_x -= 4.0
                ok
                if key[KEY_RIGHT] and bouncer_x <= SCREEN_W - BOUNCER_SIZE - 4.0
                        bouncer_x += 4.0
                ok

                redraw = true

        on ALLEGRO_EVENT_MOUSE_AXES
                bouncer_x = al_get_allegro_event_mouse_x(ev)
                bouncer_y = al_get_allegro_event_mouse_y(ev)
        on ALLEGRO_EVENT_MOUSE_ENTER_DISPLAY
                bouncer_x = al_get_allegro_event_mouse_x(ev)
                bouncer_y = al_get_allegro_event_mouse_y(ev)
        on ALLEGRO_EVENT_MOUSE_BUTTON_UP
                exit
        on ALLEGRO_EVENT_KEY_DOWN
                switch al_get_allegro_event_keyboard_keycode(ev)
                        on ALLEGRO_KEY_UP
                                key[KEY_UP] = true
                        on ALLEGRO_KEY_DOWN
                                key[KEY_DOWN] = true
                        on ALLEGRO_KEY_LEFT
                                key[KEY_LEFT] = true
                        on ALLEGRO_KEY_RIGHT
                                key[KEY_RIGHT] = true
                off
        on ALLEGRO_EVENT_KEY_UP
                switch al_get_allegro_event_keyboard_keycode(ev)
                        on ALLEGRO_KEY_UP
                                key[KEY_UP] = false
                        on ALLEGRO_KEY_DOWN
                                key[KEY_DOWN] = false
                        on ALLEGRO_KEY_LEFT
                                key[KEY_LEFT] = false
                        on ALLEGRO_KEY_RIGHT
                                key[KEY_RIGHT] = false
                        on ALLEGRO_KEY_ESCAPE
                                exit
                off
        off
        if redraw and al_is_event_queue_empty(event_queue)
                redraw = false
                al_clear_to_color(al_map_rgb(0,0,0))
                al_draw_bitmap(bouncer, bouncer_x, bouncer_y, 0)
                al_flip_display()
        ok
        callgc()
end

al_destroy_timer(timer)
al_destroy_allegro_event(ev)
al_destroy_allegro_timeout(timeout)
al_destroy_event_queue(event_queue)
al_destroy_bitmap(bouncer)
al_destroy_bitmap(image)
al_destroy_display(display)

Note

In the previous example we used the function callgc() which is a Ring function to force calling the Garbage collector inside the While/End loop.

Program Output:

At first the program display a messagebox

Displaying a messagebox from our program

Then we see two rectangles are moving on the screen

Animation - Moving two rectangles in the screen

Then we see an image displayed on the screen

Finally we have one rectangle, and we see it moving all of the time on the screen but we can control it using the Mouse and/or the Keyborad

Animation and Getting Input from keyboard and the mouse to move the object

Using TrueType Fonts¶

In this example we will see how to use TrueType Fonts *.ttf in our Games using Allegro

Load "gamelib.ring"

al_init()
al_init_font_addon()
al_init_ttf_addon()

display = al_create_display(800,600)

al_clear_to_color(al_map_rgb(0,0,255))
font = al_load_ttf_font("pirulen.ttf",14,0 )
al_draw_text(font, al_map_rgb(255,255,255), 10, 10,ALLEGRO_ALIGN_LEFT,
         "Welcome to the Ring programming language")
al_flip_display()
al_rest(2)

al_destroy_display(display)

Screen Shot:

Playing Sound Files¶

The next example play a sound file

Load "gamelib.ring"

al_init()
al_install_audio()
al_init_acodec_addon()
al_reserve_samples(1)

sample = al_load_sample( "footstep.wav" )

sampleid = al_new_allegro_sample_id()
al_play_sample(sample, 1.0, 0.0,1.0,ALLEGRO_PLAYMODE_LOOP,sampleid)

display = al_create_display(640,480)
al_clear_to_color(al_map_rgb(0,0,255))
al_flip_display()
al_rest(10)

al_destroy_allegro_sample_id(sampleid)
al_destroy_sample(sample)
al_destroy_display(display)

al_exit()

Scaling and Rotating Images¶

The next example display and rotate an image

Load "gamelib.ring"

al_init()
al_init_image_addon()

display = al_create_display(640,480)
al_set_target_bitmap(al_get_backbuffer(display))
al_clear_to_color(al_map_rgb(255,255,255))

image = al_load_bitmap("man2.jpg")
al_draw_rotated_bitmap(image,0,0,250,250,150,0)
al_draw_scaled_bitmap(image,0,0,250,250,20,20,400,400,0)

al_flip_display()
al_rest(2)

al_destroy_bitmap(image)
al_destroy_display(display)

Screen Shot:

Display Transparent Image¶

The next example display image with white background on another image

Load "gamelib.ring"

al_init()
al_init_image_addon()

display = al_create_display(640,480)
imageback = al_load_bitmap("palace.jpg")
al_draw_bitmap(imageback,0,0,0)

image = al_load_bitmap("man4.png")
al_convert_mask_to_alpha(image,al_map_rgb(255,255,255))
al_draw_bitmap(image,0,0,0)
al_flip_display()
al_rest(10)

al_destroy_bitmap(image)
al_destroy_display(display)

Screen Shot:

Using Threads¶

In this example we will learn how to use threads from the Allegro library

Load "gamelib.ring"

o1 = new mythreads

Func Main
        al_init()
        for k = 1 to 5
                al_create_thread("o1.thread1()")
                al_create_thread("o1.thread2()")
                al_create_thread("o1.thread3()")
        next
        al_rest(2)

Class Mythreads

        cAppName = "Threads Application"

        Func Thread1
                for x = 1 to 5
                        see x + nl
                next
                See 'Thread(1) : Application Name : '  + cAppName + nl

        Func Thread2
                for x = 1 to 5
                        see '*****' + x + nl
                next
                See 'Thread(2) : Application Name : '  + cAppName + nl

        Func Thread3
                for x = 1 to 5
                        see '!!!!' + x + nl
                next
                See 'Thread(3) : Application Name : '  + cAppName + nl

Output:

1
2
3
4
5
Thread(1) : Application Name : Threads Application
*****1
*****2
*****3
*****4
*****5
Thread(2) : Application Name : Threads Application
!!!!1
!!!!2
!!!!3
!!!!4
!!!!5
Thread(3) : Application Name : Threads Application
1
2
3
4
5
Thread(1) : Application Name : Threads Application
!!!!1
!!!!2
!!!!3
!!!!4
!!!!5
Thread(3) : Application Name : Threads Application
*****1
*****2
*****3
*****4
*****5
Thread(2) : Application Name : Threads Application
*****1
*****2
*****3
*****4
*****5
Thread(2) : Application Name : Threads Application
!!!!1
!!!!2
!!!!3
!!!!4
!!!!5
Thread(3) : Application Name : Threads Application
1
2
3
4
5
Thread(1) : Application Name : Threads Application
*****1
*****2
*****3
*****1
*****4
*****2
!!!!1
*****5
*****3
1
!!!!2
Thread(2) : Application Name : Threads Application
1
*****4
!!!!1
2
!!!!3
!!!!4
*****5
!!!!2
3
2
!!!!5
Thread(2) : Application Name : Threads Application
!!!!3
4
3
Thread(3) : Application Name : Threads Application
!!!!4
5
4
!!!!5
Thread(1) : Application Name : Threads Application
5
Thread(3) : Application Name : Threads Application
Thread(1) : Application Name : Threads Application

Graphics and 2D Games programming using RingAllegro¶

Drawing, Animation and Input¶

Using TrueType Fonts¶

Playing Sound Files¶

Scaling and Rotating Images¶

Display Transparent Image¶

Using Threads¶

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