WhatsNew
author Sam Lantinga <slouken@libsdl.org>
Tue, 22 Jul 2003 15:10:06 +0000
changeset 655 9c42ee1b7d77
parent 648 12a21d82a060
child 656 864e2d2a9a55
permissions -rw-r--r--
Date: Thu, 24 Apr 2003 15:13:47 -0400
From: Shawn Kirst
Subject: SDL-1.2.5 patch to add ARB_multisample support

Attached is a patch I have written for SDL-1.2.5 that adds ARB_multisample
support. I only have the X11 and Win32 video patched. The Win32 patch also
adds support for WGL_ARB_pixel_format, as it was required for getting a
multisample capable pixel format. No additional GL header files are required
to compile on either platform (though you need an up-to-date glx.h for X11).

Requesting a multisample pixel format is made possible using
SDL_GL_SetAttribute with the two new SDL_GLattr's I've added
(SDL_GL_SAMPLE_BUFFERS and SDL_GL_SAMPLES). I've been using SDL in my
projects for quite a while now, so I am happy to contribute back to the
project. Now you can have and control FSAA in your SDL/GL apps at the
application level!
     1 
     2 This is a list of API changes in SDL's version history.
     3 
     4 Version 1.0:
     5 
     6 1.2.6:
     7 	Added SDL_LoadObject(), SDL_LoadFunction(), and SDL_UnloadObject()
     8 
     9 	Added SDL_GL_SAMPLE_BUFFERS and SDL_GL_SAMPLES for FSAA support
    10 
    11 1.2.5:
    12 	Added SDL_BUTTON_WHEELUP (4) and SDL_BUTTON_WHEELDOWN (5)
    13 
    14 	Added SDL_GL_STEREO for stereoscopic OpenGL contexts
    15 
    16 1.2.0:
    17 	Added SDL_VIDEOEXPOSE event to signal that the screen needs to
    18 	be redrawn.  This is currently only delivered to OpenGL windows
    19 	on X11, though it may be delivered in the future when the video
    20 	memory is lost under DirectX.
    21 
    22 1.1.8:
    23 	You can pass SDL_NOFRAME to SDL_VideoMode() to create a window
    24 	that has no title bar or frame decoration.  Fullscreen video
    25 	modes automatically have this flag set.
    26 
    27 	Added a function to query the clipping rectangle for a surface:
    28 		void SDL_GetClipRect(SDL_Surface *surface, SDL_Rect *rect)
    29 
    30 	Added a function to query the current event filter:
    31 		SDL_EventFilter SDL_GetEventFilter(void)
    32 
    33 	If you pass -1 to SDL_ShowCursor(), it won't change the current
    34 	cursor visibility state, but will still return it.
    35 
    36 	SDL_LockSurface() and SDL_UnlockSurface() are recursive, meaning
    37 	you can nest them as deep as you want, as long as each lock call
    38 	has a matching unlock call.  The surface remains locked until the
    39 	last matching unlock call.
    40 
    41 	Note that you may not blit to or from a locked surface.
    42 
    43 1.1.7:
    44 	The SDL_SetGammaRamp() and SDL_GetGammaRamp() functions now take
    45 	arrays of Uint16 values instead of Uint8 values.  For the most part,
    46 	you can just take your old values and shift them up 8 bits to get
    47 	new correct values for your gamma ramps.
    48 
    49 	You can pass SDL_RLEACCEL in flags passed to SDL_ConvertSurface()
    50         and SDL will try to RLE accelerate colorkey and alpha blits in the
    51 	resulting surface.
    52 
    53 1.1.6:
    54 	Added a function to return the thread ID of a specific thread:
    55 		Uint32 SDL_GetThreadID(SDL_Thread *thread)
    56 	If 'thread' is NULL, this function returns the id for this thread.
    57 
    58 1.1.5:
    59 	The YUV overlay structure has been changed to use an array of
    60 	pitches and pixels representing the planes of a YUV image, to
    61 	better enable hardware acceleration.  The YV12 and IYUV formats
    62 	each have three planes, corresponding to the Y, U, and V portions
    63 	of the image, while packed pixel YUV formats just have one plane.
    64 
    65 	For palettized mode (8bpp), the screen colormap is now split in
    66 	a physical and a logical palette. The physical palette determines
    67 	what colours the screen pixels will get when displayed, and the
    68 	logical palette controls the mapping from blits to/from the screen.
    69 	A new function, SDL_SetPalette() has been added to change
    70 	logical and physical palettes separately. SDL_SetColors() works
    71 	just as before, and is equivalent to calling SDL_SetPalette() with
    72 	a flag argument of (SDL_LOGPAL|SDL_PHYSPAL).
    73 
    74 	SDL_BlitSurface() no longer modifies the source rectangle, only the
    75 	destination rectangle. The width/height members of the destination
    76 	rectangle are ignored, only the position is used.
    77 
    78 	The old source clipping function SDL_SetClipping() has been replaced
    79 	with a more useful function to set the destination clipping rectangle:
    80 		SDL_bool SDL_SetClipRect(SDL_Surface *surface, SDL_Rect *rect)
    81 		
    82 	Added a function to see what subsystems have been initialized:
    83 		Uint32 SDL_WasInit(Uint32 flags)
    84 
    85 	The Big Alpha Flip: SDL now treats alpha as opacity like everybody
    86 	else, and not as transparency:
    87 
    88 	A new cpp symbol: SDL_ALPHA_OPAQUE is defined as 255
    89 	A new cpp symbol: SDL_ALPHA_TRANSPARENT is defined as 0
    90 	Values between 0 and 255 vary from fully transparent to fully opaque.
    91 
    92 	New functions:
    93 	SDL_DisplayFormatAlpha()
    94 	    Returns a surface converted to a format with alpha-channel
    95 	    that can be blit efficiently to the screen. (In other words,
    96 	    like SDL_DisplayFormat() but the resulting surface has
    97 	    an alpha channel.)  This is useful for surfaces with alpha.
    98 	SDL_MapRGBA()
    99 	    Works as SDL_MapRGB() but takes an additional alpha parameter.
   100 	SDL_GetRGBA()
   101 	    Works as SDL_GetRGB() but also returns the alpha value
   102 	    (SDL_ALPHA_OPAQUE for formats without an alpha channel)
   103 
   104 	Both SDL_GetRGB() and SDL_GetRGBA() now always return values in
   105 	the [0..255] interval. Previously, SDL_GetRGB() would return
   106 	(0xf8, 0xfc, 0xf8) for a completely white pixel in RGB565 format.
   107 	(N.B.: This is broken for bit fields < 3 bits.)
   108 
   109 	SDL_MapRGB() returns pixels in which the alpha channel is set opaque.
   110 
   111 	SDL_SetAlpha() can now be used for both setting the per-surface
   112 	alpha, using the new way of thinking of alpha, and also to enable
   113 	and disable per-pixel alpha blending for surfaces with an alpha
   114 	channel:
   115 		To disable alpha blending:
   116 			SDL_SetAlpha(surface, 0, 0);
   117 		To re-enable alpha blending:
   118 			SDL_SetAlpha(surface, SDL_SRCALPHA, 0);
   119 	Surfaces with an alpha channel have blending enabled by default.
   120 
   121 	SDL_SetAlpha() now accepts SDL_RLEACCEL as a flag, which requests
   122 	RLE acceleration of blits, just as like with SDL_SetColorKey().
   123 	This flag can be set for both surfaces with an alpha channel
   124 	and surfaces with an alpha value set by SDL_SetAlpha().
   125 	As always, RLE surfaces must be locked before pixel access is
   126 	allowed, and unlocked before any other SDL operations are done
   127 	on it.
   128 
   129 	The blit semantics for surfaces with and without alpha and colorkey
   130 	have now been defined:
   131 
   132 	RGBA->RGB:
   133 	    SDL_SRCALPHA set:
   134 		alpha-blend (using alpha-channel).
   135 		SDL_SRCCOLORKEY ignored.
   136 	    SDL_SRCALPHA not set:
   137 		copy RGB.
   138 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   139 		RGB values of the source colour key, ignoring alpha in the
   140 		comparison.
   141 
   142 	RGB->RGBA:
   143 	    SDL_SRCALPHA set:
   144 		alpha-blend (using the source per-surface alpha value);
   145 		set destination alpha to opaque.
   146 	    SDL_SRCALPHA not set:
   147 		copy RGB, set destination alpha to opaque.
   148 	    both:
   149 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   150 		source colour key.
   151 
   152 	RGBA->RGBA:
   153 	    SDL_SRCALPHA set:
   154 		alpha-blend (using the source alpha channel) the RGB values;
   155 		leave destination alpha untouched. [Note: is this correct?]
   156 		SDL_SRCCOLORKEY ignored.
   157 	    SDL_SRCALPHA not set:
   158 		copy all of RGBA to the destination.
   159 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   160 		RGB values of the source colour key, ignoring alpha in the
   161 		comparison.
   162 
   163 	RGB->RGB: 
   164 	    SDL_SRCALPHA set:
   165 		alpha-blend (using the source per-surface alpha value).
   166 	    SDL_SRCALPHA not set:
   167 		copy RGB.
   168 	    both:
   169 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   170 		source colour key.
   171 
   172 	As a special case, blits from surfaces with per-surface alpha
   173 	value of 128 (50% transparency) are optimised and much faster
   174 	than other alpha values. This does not apply to surfaces with
   175 	alpha channels (per-pixel alpha).
   176 
   177 	New functions for manipulating the gamma of the display have
   178 	been added:
   179 		int SDL_SetGamma(float red, float green, float blue);
   180 		int SDL_SetGammaRamp(Uint8 *red, Uint8 *green, Uint8 *blue);
   181 		int SDL_GetGammaRamp(Uint8 *red, Uint8 *green, Uint8 *blue);
   182 	Gamma ramps are tables with 256 entries which map the screen color
   183 	components into actually displayed colors.  For an example of
   184 	implementing gamma correction and gamma fades, see test/testgamma.c
   185 	Gamma control is not supported on all hardware.
   186 
   187 1.1.4:
   188 	The size of the SDL_CDtrack structure changed from 8 to 12 bytes
   189 	as the size of the length member was extended to 32 bits.
   190 
   191         You can now use SDL for 2D blitting with a GL mode by passing the
   192 	SDL_OPENGLBLIT flag to SDL_SetVideoMode().  You can specify 16 or
   193 	32 bpp, and the data in the framebuffer is put into the GL scene
   194 	when you call SDL_UpdateRects(), and the scene will be visible
   195 	when you call SDL_GL_SwapBuffers().
   196 
   197 	Run the "testgl" test program with the -logo command line option
   198 	to see an example of this blending of 2D and 3D in SDL.
   199 
   200 1.1.3:
   201 	Added SDL_FreeRW() to the API, to complement SDL_AllocRW()
   202 
   203 	Added resizable window support - just add SDL_RESIZABLE to the
   204 	SDL_SetVideoMode() flags, and then wait for SDL_VIDEORESIZE events.
   205 	See SDL_events.h for details on the new SDL_ResizeEvent structure.
   206 
   207 	Added condition variable support, based on mutexes and semaphores.
   208 		SDL_CreateCond()
   209 		SDL_DestroyCond()
   210 		SDL_CondSignal()
   211 		SDL_CondBroadcast()
   212 		SDL_CondWait()
   213 		SDL_CondTimedWait()
   214 	The new function prototypes are in SDL_mutex.h
   215 
   216 	Added counting semaphore support, based on the mutex primitive.
   217 		SDL_CreateSemaphore()
   218 		SDL_DestroySemaphore()
   219 		SDL_SemWait()
   220 		SDL_SemTryWait()
   221 		SDL_SemWaitTimeout()
   222 		SDL_SemPost()
   223 		SDL_SemValue()
   224 	The new function prototypes are in SDL_mutex.h
   225 
   226 	Added support for asynchronous blitting.  To take advantage of this,
   227 	you must set the SDL_ASYNCBLIT flag when setting the video mode and
   228 	creating surfaces that you want accelerated in this way.  You must
   229 	lock surfaces that have this flag set, and the lock will block until
   230 	any queued blits have completed.
   231 
   232 	Added YUV video overlay support.
   233 	The supported YUV formats are: YV12, IYUV, YUY2, UYVY, and YVYU.
   234 	This function creates an overlay surface:
   235 		SDL_CreateYUVOverlay()
   236 	You must lock and unlock the overlay to get access to the data:
   237 		SDL_LockYUVOverlay() SDL_UnlockYUVOverlay()
   238 	You can then display the overlay:
   239 		SDL_DisplayYUVOverlay()
   240 	You must free the overlay when you are done using it:
   241 		SDL_FreeYUVOverlay()
   242 	See SDL_video.h for the full function prototypes.
   243 
   244 	The joystick hat position constants have been changed:
   245 	Old constant            New constant
   246 	------------            ------------
   247 	     0                  SDL_HAT_CENTERED
   248 	     1                  SDL_HAT_UP
   249 	     2                  SDL_HAT_RIGHTUP
   250 	     3                  SDL_HAT_RIGHT
   251 	     4                  SDL_HAT_RIGHTDOWN
   252 	     5                  SDL_HAT_DOWN
   253 	     6                  SDL_HAT_LEFTDOWN
   254 	     7                  SDL_HAT_LEFT
   255 	     8                  SDL_HAT_LEFTUP
   256 	The new constants are bitmasks, so you can check for the
   257 	individual axes like this:
   258 		if ( hat_position & SDL_HAT_UP ) {
   259 		}
   260 	and you'll catch left-up, up, and right-up.
   261 
   262 1.1.2:
   263 	Added multiple timer support:
   264 		SDL_AddTimer() and SDL_RemoveTimer()
   265 
   266 	SDL_WM_SetIcon() now respects the icon colorkey if mask is NULL.
   267 
   268 1.1.0:
   269 	Added initial OpenGL support.
   270 	First set GL attributes (such as RGB depth, alpha depth, etc.)
   271 		SDL_GL_SetAttribute()
   272 	Then call SDL_SetVideoMode() with the SDL_OPENGL flag.
   273 	Perform all of your normal GL drawing.
   274 	Finally swap the buffers with the new SDL function:
   275 		SDL_GL_SwapBuffers()
   276 	See the new 'testgl' test program for an example of using GL with SDL.
   277 
   278 	You can load GL extension functions by using the function:
   279 		SDL_GL_LoadProcAddress()
   280 
   281 	Added functions to initialize and cleanup specific SDL subsystems:
   282 		SDL_InitSubSystem() and SDL_QuitSubSystem()
   283 
   284 	Added user-defined event type:
   285 		typedef struct {
   286         		Uint8 type;
   287         		int code;
   288         		void *data1;
   289         		void *data2;
   290 		} SDL_UserEvent;
   291 	This structure is in the "user" member of an SDL_Event.
   292 
   293 	Added a function to push events into the event queue:
   294 		SDL_PushEvent()
   295 
   296 	Example of using the new SDL user-defined events:
   297 	{
   298 		SDL_Event event;
   299 
   300 		event.type = SDL_USEREVENT;
   301 		event.user.code = my_event_code;
   302 		event.user.data1 = significant_data;
   303 		event.user.data2 = 0;
   304 		SDL_PushEvent(&event);
   305 	}
   306 
   307 	Added a function to get mouse deltas since last query:
   308 		SDL_GetRelativeMouseState()
   309 
   310 	Added a boolean datatype to SDL_types.h:
   311 		SDL_bool = { SDL_TRUE, SDL_FALSE }
   312 
   313 	Added a function to get the current audio status:
   314 		SDL_GetAudioState();
   315 	It returns one of:
   316 		SDL_AUDIO_STOPPED,
   317 		SDL_AUDIO_PLAYING,
   318 		SDL_AUDIO_PAUSED
   319 
   320 	Added an AAlib driver (ASCII Art) - by Stephane Peter.
   321 
   322 1.0.6:
   323 	The input grab state is reset after each call to SDL_SetVideoMode().
   324 	The input is grabbed by default in fullscreen mode, and ungrabbed in
   325 	windowed mode.  If you want to set input grab to a particular value,
   326 	you should set it after each call to SDL_SetVideoMode().
   327 
   328 1.0.5:
   329 	Exposed SDL_AudioInit(), SDL_VideoInit()
   330 	Added SDL_AudioDriverName() and SDL_VideoDriverName()
   331 
   332 	Added new window manager function:
   333 		SDL_WM_ToggleFullScreen()
   334 	This is currently implemented only on Linux
   335 
   336 	The ALT-ENTER code has been removed - it's not appropriate for a
   337 	lib to bind keys when they aren't even emergency escape sequences.
   338 
   339 	ALT-ENTER functionality can be implemented with the following code:
   340 
   341 	int Handle_AltEnter(const SDL_Event *event)
   342 	{
   343 	    if ( event->type == SDL_KEYDOWN ) {
   344 	        if ( (event->key.keysym.sym == SDLK_RETURN) &&
   345 	             (event->key.keysym.mod & KMOD_ALT) ) {   
   346 	                SDL_WM_ToggleFullScreen(SDL_GetVideoSurface());
   347 	                return(0);
   348 	        }
   349 	    }
   350 	    return(1);
   351 	}
   352 	SDL_SetEventFilter(Handle_AltEnter);
   353 
   354 1.0.3:
   355 	Under X11, if you grab the input and hide the mouse cursor,
   356 	the mouse will go into a "relative motion" mode where you
   357 	will always get relative motion events no matter how far in
   358 	each direction you move the mouse - relative motion is not
   359 	bounded by the edges of the window (though the absolute values
   360 	of the mouse positions are clamped by the size of the window).
   361 	The SVGAlib, framebuffer console, and DirectInput drivers all
   362 	have this behavior naturally, and the GDI and BWindow drivers
   363 	never go into "relative motion" mode.
   364 
   365 1.0.2:
   366 	Added a function to enable keyboard repeat:
   367 		SDL_EnableKeyRepeat()
   368 
   369 	Added a function to grab the mouse and keyboard input
   370 		SDL_WM_GrabInput()
   371 
   372 	Added a function to iconify the window.
   373 		SDL_WM_IconifyWindow()
   374 	If this function succeeds, the application will receive an event
   375 	signaling SDL_APPACTIVE event 
   376 
   377 1.0.1:
   378 	Added constants to SDL_audio.h for 16-bit native byte ordering:
   379 		AUDIO_U16SYS, AUDIO_S16SYS
   380 
   381 1.0.0:
   382 	New public release
   383 
   384 Version 0.11:
   385 
   386 0.11.5:
   387 	A new function SDL_GetVideoSurface() has been added, and returns
   388 	a pointer to the current display surface.
   389 
   390 	SDL_AllocSurface() has been renamed SDL_CreateRGBSurface(), and
   391 	a new function SDL_CreateRGBSurfaceFrom() has been added to allow
   392 	creating an SDL surface from an existing pixel data buffer.
   393 
   394 	Added SDL_GetRGB() to the headers and documentation.
   395 
   396 0.11.4:
   397 	SDL_SetLibraryPath() is no longer meaningful, and has been removed.
   398 
   399 0.11.3:
   400 	A new flag for SDL_Init(), SDL_INIT_NOPARACHUTE, prevents SDL from
   401 	installing fatal signal handlers on operating systems that support
   402 	them.
   403 
   404 Version 0.9:
   405 
   406 0.9.15:
   407 	SDL_CreateColorCursor() has been removed.  Color cursors should
   408 	be implemented as sprites, blitted by the application when the
   409 	cursor moves.  To get smooth color cursor updates when the app
   410 	is busy, pass the SDL_INIT_EVENTTHREAD flag to SDL_Init().  This
   411 	allows you to handle the mouse motion in another thread from an
   412 	event filter function, but is currently only supported by Linux
   413 	and BeOS.  Note that you'll have to protect the display surface
   414 	from multi-threaded access by using mutexes if you do this.
   415 
   416 	Thread-safe surface support has been removed from SDL.
   417 	This makes blitting somewhat faster, by removing SDL_MiddleBlit().
   418 	Code that used SDL_MiddleBlit() should use SDL_LowerBlit() instead.
   419 	You can make your surfaces thread-safe by allocating your own
   420 	mutex and making lock/unlock calls around accesses to your surface.
   421 
   422 0.9.14:
   423 	SDL_GetMouseState() now takes pointers to int rather than Uint16.
   424 
   425 	If you set the SDL_WINDOWID environment variable under UNIX X11,
   426 	SDL will use that as the main window instead of creating it's own.
   427 	This is an unsupported extension to SDL, and not portable at all.
   428 
   429 0.9.13:
   430 	Added a function SDL_SetLibraryPath() which can be used to specify
   431 	the directory containing the SDL dynamic libraries.  This is useful
   432 	for commercial applications which ship with particular versions
   433 	of the libraries, and for security on multi-user systems.
   434 	If this function is not used, the default system directories are 
   435 	searched using the native dynamic object loading mechanism.
   436 
   437 	In order to support C linkage under Visual C++, you must declare
   438 	main() without any return type:
   439 		main(int argc, char *argv[]) {
   440 			/* Do the program... */
   441 			return(0);
   442 		}
   443 	C++ programs should also return a value if compiled under VC++.
   444 
   445 	The blit_endian member of the SDL_VideoInfo struct has been removed.
   446 
   447 	SDL_SymToASCII() has been replaced with SDL_GetKeyName(), so there
   448 	is now no longer any function to translate a keysym to a character.
   449 
   450 	The SDL_keysym structure has been extended with a 'scancode' and
   451 	'unicode' member.  The 'scancode' is a hardware specific scancode
   452 	for the key that was pressed, and may be 0.  The 'unicode' member
   453 	is a 16-bit UNICODE translation of the key that was pressed along
   454 	with any modifiers or compose keys that have been pressed.
   455 	If no UNICODE translation exists for the key, 'unicode' will be 0.
   456 
   457 	Added a function SDL_EnableUNICODE() to enable/disable UNICODE
   458 	translation of character keypresses.  Translation defaults off.
   459 
   460 	To convert existing code to use the new API, change code which
   461 	uses SDL_SymToASCII() to get the keyname to use SDL_GetKeyName(),
   462 	and change code which uses it to get the ASCII value of a sym to
   463 	use the 'unicode' member of the event keysym.
   464 
   465 0.9.12:
   466 	There is partial support for 64-bit datatypes.  I don't recommend 
   467 	you use this if you have a choice, because 64-bit datatypes are not
   468 	supported on many platforms.  On platforms for which it is supported,
   469 	the SDL_HAS_64BIT_TYPE C preprocessor define will be enabled, and
   470 	you can use the Uint64 and Sint64 datatypes.
   471 
   472 	Added functions to SDL_endian.h to support 64-bit datatypes:
   473 	    SDL_SwapLE64(), SDL_SwapBE64(),
   474 	    SDL_ReadLE64(), SDL_ReadBE64(), SDL_WriteLE64(), SDL_WriteBE64()
   475 
   476 	A new member "len_ratio" has been added to the SDL_AudioCVT structure,
   477 	and allows you to determine either the original buffer length or the
   478 	converted buffer length, given the other.
   479 
   480 	A new function SDL_FreeWAV() has been added to the API to free data
   481 	allocated by SDL_LoadWAV_RW().  This is necessary under Win32 since
   482 	the gcc compiled DLL uses a different heap than VC++ compiled apps.
   483 
   484 	SDL now has initial support for international keyboards using the
   485 	Latin character set.
   486 	If a particular mapping is desired, you can set the DEFAULT_KEYBOARD
   487 	compile-time variable, or you can set the environment variable 
   488 	"SDL_KEYBOARD" to a string identifying the keyboard mapping you desire.
   489 	The valid values for these variables can be found in SDL_keyboard.c
   490 
   491 	Full support for German and French keyboards under X11 is implemented.
   492 
   493 0.9.11:
   494 	The THREADED_EVENTS compile-time define has been replaced with the
   495 	SDL_INIT_EVENTTHREAD flag.  If this flag is passed to SDL_Init(),
   496 	SDL will create a separate thread to perform input event handling.
   497 	If this flag is passed to SDL_Init(), and the OS doesn't support 
   498 	event handling in a separate thread, SDL_Init() will fail.
   499 	Be sure to add calls to SDL_Delay() in your main thread to allow
   500 	the OS to schedule your event thread, or it may starve, leading
   501 	to slow event delivery and/or dropped events.
   502 	Currently MacOS and Win32 do not support this flag, while BeOS 
   503 	and Linux do support it.  I recommend that your application only
   504 	use this flag if absolutely necessary.
   505 
   506 	The SDL thread function passed to SDL_CreateThread() now returns a
   507 	status.  This status can be retrieved by passing a non-NULL pointer
   508 	as the 'status' argument to SDL_WaitThread().
   509 
   510 	The volume parameter to SDL_MixAudio() has been increased in range
   511 	from (0-8) to (0-128)
   512 
   513 	SDL now has a data source abstraction which can encompass a file,
   514 	an area of memory, or any custom object you can envision.  It uses
   515 	these abstractions, SDL_RWops, in the endian read/write functions,
   516 	and the built-in WAV and BMP file loaders.  This means you can load
   517 	WAV chunks from memory mapped files, compressed archives, network
   518 	pipes, or anything else that has a data read abstraction.
   519 
   520 	There are three built-in data source abstractions:
   521 	    SDL_RWFromFile(), SDL_RWFromFP(), SDL_RWFromMem()
   522 	along with a generic data source allocation function:
   523 	    SDL_AllocRW()
   524 	These data sources can be used like stdio file pointers with the
   525 	following convenience functions:
   526 	    SDL_RWseek(), SDL_RWread(), SDL_RWwrite(), SDL_RWclose()
   527 	These functions are defined in the new header file "SDL_rwops.h"
   528 
   529 	The endian swapping functions have been turned into macros for speed
   530 	and SDL_CalculateEndian() has been removed.  SDL_endian.h now defines
   531 	SDL_BYTEORDER as either SDL_BIG_ENDIAN or SDL_LIL_ENDIAN depending on
   532 	the endianness of the host system.
   533 
   534 	The endian read/write functions now take an SDL_RWops pointer
   535 	instead of a stdio FILE pointer, to support the new data source
   536 	abstraction.
   537 
   538 	The SDL_*LoadWAV() functions have been replaced with a single
   539 	SDL_LoadWAV_RW() function that takes a SDL_RWops pointer as it's
   540 	first parameter, and a flag whether or not to automatically 
   541 	free it as the second parameter.  SDL_LoadWAV() is a macro for
   542 	backward compatibility and convenience:
   543 	    SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...);
   544 
   545 	The SDL_*LoadBMP()/SDL_*SaveBMP() functions have each been replaced
   546 	with a single function that takes a SDL_RWops pointer as it's
   547 	first parameter, and a flag whether or not to automatically 
   548 	free it as the second parameter.  SDL_LoadBMP() and SDL_SaveBMP()
   549 	are macros for backward compatibility and convenience:
   550 	    SDL_LoadBMP_RW(SDL_RWFromFile("sample.bmp", "rb"), 1, ...);
   551 	    SDL_SaveBMP_RW(SDL_RWFromFile("sample.bmp", "wb"), 1, ...);
   552 	Note that these functions use SDL_RWseek() extensively, and should
   553 	not be used on pipes or other non-seekable data sources.
   554 
   555 0.9.10:
   556 	The Linux SDL_SysWMInfo and SDL_SysWMMsg structures have been 
   557 	extended to support multiple types of display drivers, as well as
   558         safe access to the X11 display when THREADED_EVENTS is enabled.
   559         The new structures are documented in the SDL_syswm.h header file.
   560 
   561 	Thanks to John Elliott <jce@seasip.demon.co.uk>, the UK keyboard
   562 	should now work properly, as well as the "Windows" keys on US
   563 	keyboards.
   564 
   565 	The Linux CD-ROM code now reads the CD-ROM devices from /etc/fstab
   566 	instead of trying to open each block device on the system.
   567 	The CD must be listed in /etc/fstab as using the iso9660 filesystem.
   568 
   569 	On Linux, if you define THREADED_EVENTS at compile time, a separate
   570 	thread will be spawned to gather X events asynchronously from the
   571 	graphics updates.  This hasn't been extensively tested, but it does
   572 	provide a means of handling keyboard and mouse input in a separate
   573 	thread from the graphics thread.  (This is now enabled by default.)
   574 
   575 	A special access function SDL_PeepEvents() allows you to manipulate
   576 	the event queue in a thread-safe manner, including peeking at events,
   577 	removing events of a specified type, and adding new events of arbitrary
   578 	type to the queue (use the new 'user' member of the SDL_Event type).
   579 
   580 	If you use SDL_PeepEvents() to gather events, then the main graphics
   581 	thread needs to call SDL_PumpEvents() periodically to drive the event
   582 	loop and generate input events.  This is not necessary if SDL has been 
   583 	compiled with THREADED_EVENTS defined, but doesn't hurt.
   584 
   585 	A new function SDL_ThreadID() returns the identifier associated with
   586 	the current thread.
   587 
   588 0.9.9:
   589 	The AUDIO_STEREO format flag has been replaced with a new 'channels'
   590 	member of the SDL_AudioSpec structure.  The channels are 1 for mono
   591 	audio, and 2 for stereo audio.  In the future more channels may be
   592 	supported for 3D surround sound.
   593 
   594 	The SDL_MixAudio() function now takes an additional volume parameter,
   595 	which should be set to SDL_MIX_MAXVOLUME for compatibility with the
   596 	original function.
   597 
   598 	The CD-ROM functions which take a 'cdrom' parameter can now be
   599 	passed NULL, and will act on the last successfully opened CD-ROM.
   600 
   601 0.9.8:
   602 	No changes, bugfixes only.
   603 	
   604 0.9.7:
   605 	No changes, bugfixes only.
   606 	
   607 0.9.6:
   608 	Added a fast rectangle fill function: SDL_FillRect()
   609 
   610 	Addition of a useful function for getting info on the video hardware:
   611 	    const SDL_VideoInfo *SDL_GetVideoInfo(void)
   612         This function replaces SDL_GetDisplayFormat().
   613 
   614 	Initial support for double-buffering:
   615 	  Use the SDL_DOUBLEBUF flag in SDL_SetVideoMode()
   616 	  Update the screen with a new function: SDL_Flip()
   617 
   618 	SDL_AllocSurface() takes two new flags:
   619 	SDL_SRCCOLORKEY means that the surface will be used for colorkey blits
   620 	  and if the hardware supports hardware acceleration of colorkey blits
   621 	  between two surfaces in video memory, to place the surface in video
   622 	  memory if possible, otherwise it will be placed in system memory.
   623 	SDL_SRCALPHA means that the surface will be used for alpha blits and
   624 	  if the hardware supports hardware acceleration of alpha blits between
   625 	  two surfaces in video memory, to place the surface in video memory
   626 	  if possible, otherwise it will be placed in system memory.
   627 	SDL_HWSURFACE now means that the surface will be created with the 
   628 	  same format as the display surface, since having surfaces in video
   629 	  memory is only useful for fast blitting to the screen, and you can't
   630 	  blit surfaces with different surface formats in video memory.
   631 
   632 0.9.5:
   633 	You can now pass a NULL mask to SDL_WM_SetIcon(), and it will assume
   634 	that the icon consists of the entire image.
   635 
   636 	SDL_LowerBlit() is back -- but don't use it on the display surface.
   637 	It is exactly the same as SDL_MiddleBlit(), but doesn't check for
   638 	thread safety.
   639 
   640 	Added SDL_FPLoadBMP(), SDL_FPSaveBMP(), SDL_FPLoadWAV(), which take
   641 	a FILE pointer instead of a file name.
   642 
   643 	Added CD-ROM audio control API:
   644 	    SDL_CDNumDrives()
   645 	    SDL_CDName()
   646 	    SDL_CDOpen()
   647 	    SDL_CDStatus()
   648 	    SDL_CDPlayTracks()
   649 	    SDL_CDPlay()
   650 	    SDL_CDPause()
   651 	    SDL_CDResume()
   652 	    SDL_CDStop()
   653 	    SDL_CDEject()
   654 	    SDL_CDClose()
   655 
   656 0.9.4:
   657 	No changes, bugfixes only.
   658 
   659 0.9.3:
   660 	Mouse motion event now includes relative motion information:
   661 	    Sint16 event->motion.xrel, Sint16 event->motion.yrel
   662 
   663 	X11 keyrepeat handling can be disabled by defining IGNORE_X_KEYREPEAT
   664 	    (Add -DIGNORE_X_KEYREPEAT to CFLAGS line in obj/x11Makefile)
   665 
   666 0.9.2:
   667 	No changes, bugfixes only.
   668 
   669 0.9.1:
   670 	Removed SDL_MapSurface() and SDL_UnmapSurface() -- surfaces are now
   671 	automatically mapped on blit.
   672 
   673 0.8.0:
   674 	SDL stable release