FPC and SDL/zh CN

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简介

关于SDL的详细信息和文档，请访问 SDL homepage. This page is going to explain how to use SDL with Free Pascal, where to obtain the pascal headers etc.

取得FPC 的 SDL 头文件

After installing SDL itself on your system you'll need pascal headers to be able to use SDL with FPC. Since version 2.2.2, most SDL units are included with FPC itself. You can of course also download them from JEDI-SDL in case you need some bug fix or a unit not in the version shipped with FPC.

来自 JEDI-SDL 的 SDL 头文件

查看 JEDI-SDL Home Page. 你能下载到 JEDI-SDLv1.0 Beta..

You can also download and browse current CVS sources, see JEDI-SDL SourceForge CVS for instructions. In short, just do 

  cvs -d:pserver:anonymous@jedi-sdl.cvs.sourceforge.net:/cvsroot/jedi-sdl login

(when prompted for a password, simply press the Enter key) 

  cvs -z3 -d:pserver:anonymous@jedi-sdl.cvs.sourceforge.net:/cvsroot/jedi-sdl co JEDI-SDLv1.0

After you downloaded (and eventually unpacked) JEDI-SDL sources, you want to be able to use these units in your programs. For the simplest scenario, just add the following lines to your fpc.cfg file: 

 -Fi<jedi-sdl-path>/JEDI-SDLv1.0/SDL/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/SDL/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/SDL_Mixer/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/SDL_Image/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/SDL_Net/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/SDL_ttf/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/smpeg/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/SFont/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/SDL_Sound/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/SDLMonoFonts/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/SDLSpriteEngine/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/Cal3D/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/ODE/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/SDLCtrls/Pas
 -Fu<jedi-sdl-path>/JEDI-SDLv1.0/SDL_flic/Pas

(where <jedi-sdl-path> is the path where you placed jedi-sdl sources).

或者, 你复制所有的 *.pas 和 *.inc 文件到你指定的目录，并且你必须把你选定的目录修正到 fpc.cfg.

测试那些……, 你可以编译和运行许多Demo 程序, 例如下面这样. 

 cd <jedi-sdl-path>/JEDI-SDLv1.0/SDLSpriteEngine/Demos/Oxygene/
 fpc -Sd Oxygene.dpr
 ./Oxygene

Note that all jedi-sdl code should be compiled in Delphi-compatible mode. Most jedi-sdl units include jedi-sdl.inc that already has the line {$mode delphi} added, but some example programs don't include jedi-sdl.inc. So be sure to compiled them with -Sd command-line option (or add {$mode delphi} directive).

SDL headers from FreePascal CVS (deprecated)

Get them using CVS: 

cvs -d :pserver:cvs@cvs.freepascal.org:/FPC/CVS login

(password is 'cvs') 

cvs -d :pserver:cvs@cvs.freepascal.org:/FPC/CVS -z3 co projects/contrib/sdl

Tips and tricks

SDL_mixer library

When using SDL_mixer, the call to Mix_OpenAudio MUST happen before the call to SDL_SetVideoMode, otherwise you will get a ( sometimes load ) audible pop.

SMPEG library

If you use SDL_mixer you'll notice that it's dependent on smpeg library. For modern Linux distros and FreeBSD this is not a problem (because smpeg is distributed with them), but it can be troublesome e.g. for Windows. You can get smpeg.dll for Windows from SDL_sound for Visual C sources.

Alternatively, you can simply modify the source of SDL_mixer.pas: remove smpeg from it's uses clause and comment out one line in the sources mentioning mp3s (it's a case near the end). Remember that you will also need to have SDL_mixer dll/so that is not linked to smpeg -- otherwise SDL_mixer library will depend on smpeg anyway.

Mac OS X specific issues

SDL 架构 and SDL 库

On Mac OS X, SDL uses Cocoa to setup the drawing window and to handle all events (such as keypresses). This is done using a small piece of code that is automatically called when the program starts up, and which subsequently calls a function with the name SDLmain. More information is available at http://www.libsdl.org/faq.php?action=listentries&category=7#55

There are however two different ways to package/distribute SDL for Mac OS X, and depending on which version you use, the procedure to get this startup code into your program is slightly different.

架构版本

This the version that you get when you download the Mac OS X version of SDL from libsdl.org. In this case, the startup code is only available in source form. It is located on the installation disk image, in the folder devel-lite. After copying the SDL.framework from the disk image to /Library/Frameworks and copying the devel-lite folder anywhere on your hard drive (e.g., in your home directory), you can compile it into libSDLMain.a by opening a Terminal session, navigating to the copied devel-lite folder, and executing the following commands: 

gcc -c -o SDLMain.o SDLMain.m -I /Library/Frameworks/SDL.framework/Headers
ar r libSDLMain.a SDLMain.o
ranlib libSDLMain.a

You can then move the generated libSDLMain.a librray anywhere you want. To make sure the linker can find it when you compile SDL applications, pass the -Fl/full/path/to/folder/containing/libSDLMain.a command line parameter to the compiler.

Unix 库版本

There is also a "classic Unix" version of SDL for Mac OS X (no framework, just a bunch of separate libraries), which you get if you compile SDL from sources, or if you install SDL using Fink or MacPorts. In this case, libSDLmain.a is already included in a compiled form. You just have to use the compiler's -Fl parameter, as explained in the previous section, to make sure that the linker can find this library.

For FPC 2.2.2 and later

The SDL unit included with FPC includes all necessary framework, library and main procedure name renaming statements, so you no longer have to do anything special. Just add the sdl unit to your program and everything will be taken care of. However, the remarks about libSDLMain in the above section still hold (libSDLMain.a is required by the SDL unit included with FPC).

Note that if you use the original units as distributed by the JEDI team, you may still need to follow the instructions in the section below.

关于 FPC 2.0.2 至 2.2.0

fpc 2.0.2 至 2.2.0, and possibly also when using the original SDL units as distributed by the JEDI team, you have to use the -XMSDL_main command line option and tell the linker to include some frameworks:

1) install sdl, for example using fink.

2) Add the following to your program: 

 {$linklib gcc}
 {$linklib SDLmain}
 uses sdl;

3) Then, this command line does it: 

 fpc -XMSDL_main -k-L/sw/lib -k-lSDL -k-framework -kOpenGL -k-framework -kCocoa -Fu<pathtosdl.pas files> -Fi<pathtosdl.inc files> YourProgram.pas

If you installed the SDL libraries using fink, also add -k-L/sw/lib -k-lSDL to your fpc command.

If sdl.pas and jedi-sdl.inc are in the directory of your program, you can omit -Fu<pathtosdl.pas files> -Fi<pathtosdl.inc files>.

例程

建立一个空的 SDL 窗口: 

program sdltest;

{$linklib gcc}
{$linklib SDLmain}

uses sdl;

var scr: PSDL_Surface; // Our main screen

begin
 SDL_Init(SDL_INIT_VIDEO); // Initialize the video SDL subsystem
 scr:=SDL_SetVideoMode(640, 480, 8, SDL_SWSURFACE); // Create a software window of 640x480x8 and assign to scr
 SDL_Quit; // close the subsystems and SDL
end.

You can then compile this code with 

 fpc -Fu<pathtosdl.pas files> -Fi<pathtosdl.inc files> example.pas

如果你是使用 lazarus, 请将 "other unit files" 和 "include files" 设置正确.

译者注: 

  "other unit files" 和 "include files"两个设置项，在lazarus的Project菜单->Compiler Options (编译选项)

译者注

  英文版的官方文档我看的很是迷糊，因为我是在Ubuntu上使用Lazarus。而Linux上只有OpenGL，除此之外我别无选择。

SDL 和 JEDI-SDL

SDL 是 Simple DirectMedia Layer打头字母的简写。Simple DirectMedia Layer有简单的媒体指令层的意思。

JEDI 是 "Joint Endeavor of Delphi Innovators"打头字母的简写。Delphi Innovators共同努力。

为什么要使用SDL?

现阶段或者在未来很长的一段时间，我们与显示卡沟的办法有两种，一种是DirectX,另一种是OpenGL。这两种办法是受到主流显示卡支持的，但是当我们远离WINDOWS操作系统的时候，我们只有一个选择就是OpenGL，我很难想像在Windows以外的操作系统上使用DirectX。正如，当我想在Ubuntu上使用OpenGL的时候，我选了一个中间部份，这个中间部分就是SDL。

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