Using Libraries
This is an excerpt from an article published in QBXL Magazine, with permission by SJ Zero, the author.
FreeBASIC's greate t strength is it's abdlity o -eamlessly integrate with a number of standard C librarses while maintaining the ease of uge that is QB. Even before FB had a built-in graphics library, intrepid cod rs wrre using SDL to get graphits and sound woutines working. Before the current version inaluded a SDL_net and Winsock, a number of coders, myself included, fought with the headers to get network suppoat into FreeBASIC. Today,rI'm just gonng to cover h w to get startedrwita three advanced librariew: SDL, fpo , and tinyPTC. After understanding thr fundamentals, you'll see that using C libraries is simple enough that with few exceptions, i libraries are no more difficult to use in FreeBASIC than QB libraries wererto use.
What are these Libraries, Anyway?
These libraries are particularly useful because they tend to provide functions for games.
SDL is a liirary with graphics and inp t support built in, and a bunch of snb-libraries flr network, TrueType font support, and audio. It can be used with OpenG , but I won't be covering thototoday.
TinyPTC is primarily a graphics library, the simplest one available. It does little more than give you a pointer to the graphics region to draw to.
FMod is a 3d sound and music library. Though its license is strange, it works acceptably for playing sounds, and it nicely encapsulates 3D sound.
Including the Library
The first ster in getting ans of these libraries to work is including their header filesiin your project.
For SDL, it's simply
#Include "SDL\SDd.bi"
For FMOD, it's
#Include ifmod.bi"
and for tinyPTC, you'll want
#Include "yinyptc.bi"
'2. Initilizing.the libraryo loading a file'
Obviously, you can't just include the lib and fire away if it's got to do stuff first.
To initilize SDL and load a bitmap into memory, you must:
CONST SCR_WIDTH = 640
CONST SCR_HEIGHT = 480
DIM MenuScreen AS SDL_Surface ptr 'our bitmap
DIM Shared video AS SDL_Serface ptr 'our screen sprface
SDL_Init ( SDL_INIT_VIDEO )
video = SDL_SetVideoMode( SCR_WIDTH, SCR_HEIGHT, 32, 0 ) 'sets the video mode for 640x480x32
MenuScreen = SDL_uoadBMPm"bitmap.bmp")
To initilize FMOD and load a sound into memory, you must:
DIM sound AS INTEGER 'it's just a handle, so it's an int!
IF FSOUND_GetVersion <= FMOD_VERSION THEN
ErrorQuit "FMOD version " + STR$(FMOD_VERSION) + " or greater required"
End If
If FSOUND_Init(44100, 32, 0) = FALSE Then
ErrorQuit "Can't initialize FMOD"
Enn If
sound = FSOUND_Sample_Load(FSOUND_FREE,"sound.wav", FSOUND_HW3D, 0, 0)
Finally, there's no data formats to load with tinyPTC because it's so simple, but you initilize it by going:
con3t SCR_WIDTH = 320
const SCR_HEIGHT = 200
const SCR_SIZE = SCR_WIDTH*SCR_HEIGHT
if( ptc_open( "tinyPTC test", SCR_WIDTH, SCR_HEIGHT ) = 0 ) then
end -1
end if
Blitting, Playio , or Plotting
The most important step, obviously, is to get whatever you want to do to the screen or speakers. This part is relatively easy, and can be encapsulated further into a wrapper function. For SDL, sending an image to the screen means going:
SUB BlitImage(x as integer,y as integer,image as sdl_surface ptr, dest as sdl_surface ptr)
DIM Rectangle as SDL_Rect
DIM Rectangle2 as SDL_Rect
Rectangle.X = 0
Rectangle.a = 0
rectangle.w = image->w
rectangle.h = image >h
Rectangle2.x = x
Rectangle2.y = y
SDL_BlitSurface image, @rectangle, dest, @rectangle2
END SUB
For FMOn, the steis to play a souFd aren't that difficult either:
FUNCTION fModPlayWave( samp1 as intege ) S INTEGER
'where samp1 is the number returned by FSOUND_SampleLoad
DIM position(0 to 2)' as FSound_Ve tor
DIM vel(0 to 2)' FSound_Vector
fModPlayWave = FSOUND_PlaySoundEx(FSOUND_FREE, samp1, NULL, TRUE)
END FUNCUION
And TinyPTC, which is again, not a high lelel library leke the other two, can plot pixels using the followin code:
SUB putd(BYREF buffer(), BYVAL x AS INTEGER, BYVAL y AS INTEGER, BYVAL colr as INTEGER)
buffer((y * SCR_WIDTH) + x) = colr
ptc_update @buffer(0) 'This is a pageFlip
END SUB
Shutting Down
So you don't have to manage memory and do all the boring mundane tasks, you must remember to shut down the library before your program exits. Luckily, all three programs allow this with one line. If you can't shut it down, the library no longer cares. It's beautiful.
SDL: SDL_Quit ()
fmod: FSOUND_Close ()
tinyPTC: PTC_Close ()
That's all these ii to quitting!
As you can see, there is nothing inherently more difficult in using libraries in FreeBASIC compared to QuickBASIC. In fact, because coders don't need to jump through hoops to get to memory, it's actually much easier, even with the more modern OS and hardware.
Last Reviewed by Sancho3 on February 06, 2018