The document discusses using the RingLibSDL library to create games in Ring using SDL, SDL_image, SDL_ttf, and SDL_mixer. It provides examples of how to create a window, display images, switch between images, draw rectangles, use TTF fonts, handle events like closing the window, mouse events, and playing sounds. The examples demonstrate basic 2D game programming tasks like initializing libraries, loading assets, rendering to the screen, getting input, and playing audio.

1. Ring Documentation, Release 1.2
Screen Shot:
43.6 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"
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2. Ring Documentation, Release 1.2
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
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*****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
43.6. Using Threads 322

4. CHAPTER
FORTYFOUR
USING RINGLIBSDL
In this chapter we will learn about using RingLibSDL to create games based on the LibSDL, SDLImage, SDLTTF and
SDLMixer libraries.
Tip: RingLibSDL is not distributed with the binary releases for desktop which uses RingAllegro
Note: To use RingLibSDL, Check ring/android/ringlibsdl folder.
44.1 Create Window
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
SDL_Delay(2000)
SDL_DestroyWindow(win)
SDL_Quit()
44.2 Display Image
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
bmp = SDL_LoadBMP("hello.bmp")
tex = SDL_CreateTextureFromSurface(ren,bmp)
SDL_FreeSurface(bmp)
SDL_RenderClear(ren)
SDL_RenderCopy2(ren,tex)
SDL_RenderPresent(ren)
SDL_Delay(2000)
SDL_DestroyTexture(tex)
SDL_DestroyRenderer(ren)
SDL_DestroyWindow(win)
SDL_Quit()
323

5. Ring Documentation, Release 1.2
44.3 Switch between two images
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
bmp = SDL_LoadBMP("hello.bmp")
tex = SDL_CreateTextureFromSurface(ren,bmp)
SDL_FreeSurface(bmp)
bmp = SDL_LoadBMP("hello2.bmp")
tex2 = SDL_CreateTextureFromSurface(ren,bmp)
SDL_FreeSurface(bmp)
for x = 1 to 10 showtex(tex) showtex(tex2) next
SDL_DestroyTexture(tex)
SDL_DestroyTexture(tex2)
SDL_DestroyRenderer(ren)
SDL_DestroyWindow(win)
SDL_Quit()
func showtex oTex
SDL_RenderClear(ren)
SDL_RenderCopy2(ren,oTex)
SDL_RenderPresent(ren)
SDL_Delay(200)
44.4 Draw Rectangle
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
SDL_RenderClear(ren)
rect = sdl_new_sdl_rect()
sdl_set_sdl_rect_x(rect,10)
sdl_set_sdl_rect_y(rect,10)
sdl_set_sdl_rect_w(rect,100)
sdl_set_sdl_rect_h(rect,100)
SDL_SetRenderDrawColor(ren,255,255,255,255)
SDL_RenderDrawRect(ren,rect)
sdl_destroy_sdl_rect(rect)
SDL_RenderPresent(ren)
SDL_Delay(2000)
SDL_DestroyRenderer(ren)
SDL_DestroyWindow(win)
SDL_Quit()
44.3. Switch between two images 324

6. Ring Documentation, Release 1.2
44.5 Display PNG Images
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
bmp = IMG_Load("hello3.png")
tex = SDL_CreateTextureFromSurface(ren,bmp)
SDL_FreeSurface(bmp)
SDL_RenderClear(ren)
SDL_RenderCopy2(ren,tex)
SDL_RenderPresent(ren)
SDL_Delay(2000)
SDL_DestroyTexture(tex)
SDL_DestroyRenderer(ren)
SDL_DestroyWindow(win)
SDL_Quit()
44.6 Use TTF Fonts
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
SDL_RenderClear(ren)
TTF_Init()
font = TTF_OpenFont("pirulen.ttf", 16)
color = sdl_new_sdl_color()
sdl_set_sdl_color_r(color,0)
sdl_set_sdl_color_g(color,255)
sdl_set_sdl_color_b(color,0)
text = TTF_RenderText_Solid(font,"Welcome to the Ring language",color)
surface = SDL_GetWindowSurface(win)
SDL_BlitSurface(text, nullpointer(), surface, nullpointer())
SDL_UpdateWindowSurface(win)
SDL_Delay(2000)
SDL_Destroy_SDL_Color(color)
SDL_FreeSurface(text)
TTF_CloseFont(font)
SDL_DestroyRenderer(ren)
SDL_DestroyWindow(win)
SDL_Quit()
44.7 Display Transparent Images
Example:
44.5. Display PNG Images 325

7. Ring Documentation, Release 1.2
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
flags = IMG_INIT_JPG | IMG_INIT_PNG
IMG_Init(flags)
win = SDL_CreateWindow("Hello World!", 100, 100, 800, 600, SDL_WINDOW_SHOWN)
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
bmp = IMG_Load("stars.jpg")
tex = SDL_CreateTextureFromSurface(ren,bmp)
SDL_FreeSurface(bmp)
SDL_RenderClear(ren)
SDL_RenderCopy(ren,tex,nullpointer(),nullpointer())
SDL_DestroyTexture(tex)
bmp = IMG_Load("player.png")
# Image - Set Transparent color (white)
myformat = sdl_get_sdl_surface_format(bmp)
white = SDL_MapRGB(myformat, 255, 255, 255)
SDL_SetColorKey(bmp, SDL_True, white)
tex = SDL_CreateTextureFromSurface(ren,bmp)
SDL_FreeSurface(bmp)
rect = sdl_new_sdl_rect()
sdl_set_sdl_rect_x(rect,0)
sdl_set_sdl_rect_y(rect,0)
sdl_set_sdl_rect_w(rect,100)
sdl_set_sdl_rect_h(rect,100)
SDL_RenderCopy(ren,tex,nullpointer(),rect)
SDL_SetTextureBlendMode(tex,2)
SDL_SetTextureAlphaMod(tex,255)
sdl_set_sdl_rect_x(rect,200)
sdl_set_sdl_rect_y(rect,200)
sdl_set_sdl_rect_w(rect,100)
sdl_set_sdl_rect_h(rect,100)
SDL_RenderCopy(ren,tex,nullpointer(),rect)
SDL_DestroyTexture(tex)
SDL_Destroy_SDL_Rect(rect)
SDL_RenderPresent(ren)
SDL_Delay(2000)
SDL_DestroyRenderer(ren)
SDL_DestroyWindow(win)
SDL_Quit()
44.8 Close Window Event
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
44.8. Close Window Event 326

8. Ring Documentation, Release 1.2
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
myevent = sdl_new_sdl_event()
while true
thevent = sdl_pollevent(myevent)
switch sdl_get_sdl_event_type(myevent)
on sdl_get_sdl_quit()
exit
on sdl_get_sdl_keydown()
Key = SDL_GET_SDL_Event_key_keysym_sym(myevent)
if key = 27 exit ok
off
end
SDL_DestroyWindow(win)
SDL_Quit()
44.9 Mouse Events
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Mouse Events ", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
TTF_Init()
font = TTF_OpenFont("pirulen.ttf", 16)
color = sdl_new_sdl_color()
sdl_set_sdl_color_r(color,0)
sdl_set_sdl_color_g(color,255)
sdl_set_sdl_color_b(color,0)
surface = SDL_GetWindowSurface(win)
myevent = sdl_new_sdl_event()
while true
cMsg = ""
sdl_pollevent(myevent)
switch sdl_get_sdl_event_type(myevent)
on SDL_QUIT
exit
on SDL_KEYDOWN
Key = SDL_GET_SDL_Event_key_keysym_sym(myevent)
if key = 27 exit ok
on SDL_MOUSEBUTTONDOWN
if sdl_get_Sdl_Event_button_button(myevent) = SDL_BUTTON_LEFT
SDL_SETWINDOWTITLE(win, " Button_Left_Down " )
but sdl_get_Sdl_Event_button_button(myevent) = SDL_BUTTON_MIDDLE
SDL_SETWINDOWTITLE(win, " Button_Middle_Down " )
but sdl_get_Sdl_Event_button_button(myevent) = SDL_BUTTON_RIGHT
SDL_SETWINDOWTITLE(win, " Button_Right_Down " )
ok
on SDL_MOUSEMOTION
44.9. Mouse Events 327

9. Ring Documentation, Release 1.2
sdl_fillrect(surface,nullpointer(),0)
if sdl_get_sdl_event_motion_xrel(myevent) < 0
cMsg += " Left "
else
cMsg += " Right "
ok
if sdl_get_sdl_event_motion_yrel(myevent) < 0
cMsg += " Up "
else
cMsg += " Down "
ok
cMsg += " x = " + sdl_get_sdl_event_motion_x(myevent)
cMsg += " y = " + sdl_get_sdl_event_motion_y(myevent)
showmsg(cMsg)
off
end
SDL_Destroy_SDL_Color(Color)
TTF_CloseFont(font)
SDL_DestroyWindow(win)
SDL_Quit()
func showmsg mymsg
text = TTF_RenderText_Solid(font,mymsg,color)
SDL_BlitSurface(text, nullpointer(), surface, nullpointer())
SDL_UpdateWindowSurface(win)
SDL_FreeSurface(text)
44.10 Play Sound
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
Mix_OpenAudio( 44100, MIX_DEFAULT_FORMAT , 2, 10000)
Mix_AllocateChannels(4)
sound = Mix_LoadWav( "sound.wav" )
Mix_VolumeChunk(sound,1)
Mix_PlayChannel(1,sound,0)
myevent = sdl_new_sdl_event()
while true
thevent = sdl_pollevent(myevent)
switch sdl_get_sdl_event_type(myevent)
on sdl_get_sdl_quit()
exit
on sdl_get_sdl_keydown()
Key = SDL_GET_SDL_Event_key_keysym_sym(myevent)
if key = 27 exit ok
off
end
Mix_FreeChunk( sound )
Mix_CloseAudio()
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Mix_Quit()
SDL_DestroyWindow(win)
SDL_Quit()
44.10. Play Sound 329