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Having trouble with SDL under Mac OSX

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I'm using Xcode to compile my C++ projects and I installed SDL (hopefully I did everything correctly). When I type out this code:
#include <sdl/sdl.h>
#include <sdl/sdl_opengl.h>

int main (int argc, char** const argv) 
{
    return 0;
}



It throws this linker error at me: Undefined symbols: _main I read somewhere that I'm supposed to include SDLmain.h and SDLmain.m but when I did it threw over 1900 errors at me. Under Linux, I just had to link to the SDL library and under Windows I just had to link to SDLmain.lib. I have no idea what you're supposed to do under Mac OSX. Can someone help me get this linker error fixed?

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Quote:
Original post by Drunken_Monkey
Can someone help me get this linker error fixed?
There are several people on the forums who use SDL with OS X (myself included), so I'm sure someone will be able to help you get this sorted...

So with the code you posted, you only get linker errors? No compiler errors? (Specifically, I'm wondering if the compiler is finding the SDL header files you specified.)

Also, maybe you could post a few of the errors you get when you include the SDLmain.* files.

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Quote:
Original post by Drunken_Monkey
I'm using Xcode to compile my C++ projects and I installed SDL (hopefully I did everything correctly). When I type out this code:

*** Source Snippet Removed ***

It throws this linker error at me:

Undefined symbols:

_main


I read somewhere that I'm supposed to include SDLmain.h and SDLmain.m but when I did it threw over 1900 errors at me.

Under Linux, I just had to link to the SDL library and under Windows I just had to link to SDLmain.lib. I have no idea what you're supposed to do under Mac OSX.

Can someone help me get this linker error fixed?


1900 errors... your #include'ing an objective C file, and the 1900 errors are differences in syntax between that and c++. Because the file was included from a c++ program, the compiler tries to compile it as a c++ file.

Instead of including those files, try adding them to the project. Then, it will be compiled as an Obj-C file and can then be linked as per usual.

If need be, you can create a new objective C file, and give it the correct name, SDLMain.m and SDLMain.h Open your project, then go file->new File and chose Objective-C Class. Call it SDLMain.m, and tick the checkbox to create the header as well.

Then replace the contents of the two files with this:
"SDLMain.h"

/* SDLMain.m - main entry point for our Cocoa-ized SDL app
Initial Version: Darrell Walisser <dwaliss1@purdue.edu>
Non-NIB-Code & other changes: Max Horn <max@quendi.de>

Feel free to customize this file to suit your needs
*/


#import <Cocoa/Cocoa.h>

@interface SDLMain : NSObject
@end





"SDLMain.m"

/* SDLMain.m - main entry point for our Cocoa-ized SDL app
Initial Version: Darrell Walisser <dwaliss1@purdue.edu>
Non-NIB-Code & other changes: Max Horn <max@quendi.de>

Feel free to customize this file to suit your needs
*/


#import <SDL/SDL.h>
#import "SDLMain.h"
#import <sys/param.h> /* for MAXPATHLEN */
#import <unistd.h>

/* Use this flag to determine whether we use SDLMain.nib or not */
#define SDL_USE_NIB_FILE 0


static int gArgc;
static char **gArgv;
static int gFinderLaunch;

#if SDL_USE_NIB_FILE
/* A helper category for NSString */
@interface NSString (ReplaceSubString)
- (NSString *)stringByReplacingRange:(NSRange)aRange with:(NSString *)aString;
@end
#else
/* An internal Apple class used to setup Apple menus */
@interface NSAppleMenuController:NSObject {}
- (void)controlMenu:(NSMenu *)aMenu;
@end
#endif

@interface SDLApplication : NSApplication
@end

@implementation SDLApplication
/* Invoked from the Quit menu item */
- (void)terminate:(id)sender
{
/* Post a SDL_QUIT event */
SDL_Event event;
event.type = SDL_QUIT;
SDL_PushEvent(&event);
}
@end


/* The main class of the application, the application's delegate */
@implementation SDLMain

/* Set the working directory to the .app's parent directory */
- (void) setupWorkingDirectory:(int)shouldChdir
{
char parentdir[MAXPATHLEN];
char *c;

strncpy ( parentdir, gArgv[0], sizeof(parentdir) );
c = (char*) parentdir;

while (*c != '\0') /* go to end */
c++;

while (*c != '/') /* back up to parent */
c--;

*c++ = '\0'; /* cut off last part (binary name) */

if (shouldChdir)
{
assert ( chdir (parentdir) == 0 ); /* chdir to the binary app's parent */
assert ( chdir ("../../../") == 0 ); /* chdir to the .app's parent */
}
}

#if SDL_USE_NIB_FILE

/* Fix menu to contain the real app name instead of "SDL App" */
- (void)fixMenu:(NSMenu *)aMenu withAppName:(NSString *)appName
{
NSRange aRange;
NSEnumerator *enumerator;
NSMenuItem *menuItem;

aRange = [[aMenu title] rangeOfString:@"SDL App"];
if (aRange.length != 0)
[aMenu setTitle: [[aMenu title] stringByReplacingRange:aRange with:appName]];

enumerator = [[aMenu itemArg_ray] objectEnumerator];
while ((menuItem = [enumerator nextObject]))
{
aRange = [[menuItem title] rangeOfString:@"SDL App"];
if (aRange.length != 0)
[menuItem setTitle: [[menuItem title] stringByReplacingRange:aRange with:appName]];
if ([menuItem hasSubmenu])
[self fixMenu:[menuItem submenu] withAppName:appName];
}
[ aMenu sizeToFit ];
}

#else

void setupAppleMenu(void)
{
/* warning: this code is very odd */
NSAppleMenuController *appleMenuController;
NSMenu *appleMenu;
NSMenuItem *appleMenuItem;

appleMenuController = [[NSAppleMenuController alloc] init];
appleMenu = [[NSMenu alloc] initWithTitle:@""];
appleMenuItem = [[NSMenuItem alloc] initWithTitle:@"" action:nil keyEquivalent:@""];

[appleMenuItem setSubmenu:appleMenu];

/* yes, we do need to add it and then remove it --
if you don't add it, it doesn't get displayed
if you don't remove it, you have an extra, titleless item in the menubar
when you remove it, it appears to stick around
very, very odd */

[[NSApp mainMenu] addItem:appleMenuItem];
[appleMenuController controlMenu:appleMenu];
[[NSApp mainMenu] removeItem:appleMenuItem];
[appleMenu release];
[appleMenuItem release];
}

/* Create a window menu */
void setupWindowMenu(void)
{
NSMenu *windowMenu;
NSMenuItem *windowMenuItem;
NSMenuItem *menuItem;


windowMenu = [[NSMenu alloc] initWithTitle:@"Window"];

/* "Minimize" item */
menuItem = [[NSMenuItem alloc] initWithTitle:@"Minimize" action:@selector(performMiniaturize:) keyEquivalent:@"m"];
[windowMenu addItem:menuItem];
[menuItem release];

/* Put menu into the menubar */
windowMenuItem = [[NSMenuItem alloc] initWithTitle:@"Window" action:nil keyEquivalent:@""];
[windowMenuItem setSubmenu:windowMenu];
[[NSApp mainMenu] addItem:windowMenuItem];

/* Tell the application object that this is now the window menu */
[NSApp setWindowsMenu:windowMenu];

/* Finally give up our references to the objects */
[windowMenu release];
[windowMenuItem release];
}

/* Replacement for NSApplicationMain */
void CustomApplicationMain (argc, argv)
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
SDLMain *sdlMain;

/* Ensure the application object is initialised */
[SDLApplication sharedApplication];

/* Set up the menubar */
[NSApp setMainMenu:[[NSMenu alloc] init]];
setupAppleMenu();
setupWindowMenu();

/* Create SDLMain and make it the app delegate */
sdlMain = [[SDLMain alloc] init];
[NSApp setDelegate:sdlMain];

/* Start the main event loop */
[NSApp run];

[sdlMain release];
[pool release];
}

#endif

/* Called when the internal event loop has just started running */
- (void) applicationDidFinishLaunching: (NSNotification *) note
{
int status;

/* Set the working directory to the .app's parent directory */
[self setupWorkingDirectory:gFinderLaunch];

#if SDL_USE_NIB_FILE
/* Set the main menu to contain the real app name instead of "SDL App" */
[self fixMenu:[NSApp mainMenu] withAppName:[[NSProcessInfo processInfo] processName]];
#endif

/* Hand off to main application code */
status = SDL_main (gArgc, gArgv);

/* We're done, thank you for playing */
exit(status);
}
@end


@implementation NSString (ReplaceSubString)

- (NSString *)stringByReplacingRange:(NSRange)aRange with:(NSString *)aString
{
unsigned int bufferSize;
unsigned int selfLen = [self length];
unsigned int aStringLen = [aString length];
unichar *buffer;
NSRange localRange;
NSString *result;

bufferSize = selfLen + aStringLen - aRange.length;
buffer = NSAllocateMemoryPages(bufferSize*sizeof(unichar));

/* Get first part into buffer */
localRange.location = 0;
localRange.length = aRange.location;
[self getCharacters:buffer range:localRange];

/* Get middle part into buffer */
localRange.location = 0;
localRange.length = aStringLen;
[aString getCharacters:(buffer+aRange.location) range:localRange];

/* Get last part into buffer */
localRange.location = aRange.location + aRange.length;
localRange.length = selfLen - localRange.location;
[self getCharacters:(buffer+aRange.location+aStringLen) range:localRange];

/* Build output string */
result = [NSString stringWithCharacters:buffer length:bufferSize];

NSDeallocateMemoryPages(buffer, bufferSize);

return result;
}

@end



#ifdef main
# undef main
#endif


/* Main entry point to executable - should *not* be SDL_main! */
int main (int argc, char **argv)
{

/* Copy the arguments into a global variable */
int i;

/* This is passed if we are launched by double-clicking */
if ( argc >= 2 && strncmp (argv[1], "-psn", 4) == 0 ) {
gArgc = 1;
gFinderLaunch = YES;
} else {
gArgc = argc;
gFinderLaunch = NO;
}
gArgv = (char**) malloc (sizeof(*gArgv) * (gArgc+1));
assert (gArgv != NULL);
for (i = 0; i < gArgc; i++)
gArgv[i] = argv[i];
gArgv[i] = NULL;

#if SDL_USE_NIB_FILE
[SDLApplication poseAsClass:[NSApplication class]];
NSApplicationMain (argc, argv);
#else
CustomApplicationMain (argc, argv);
#endif
return 0;
}





As such, on OS X, this can be used to add SDL to any existing project.

You will then need to add the SDL.framework file, and edit the compiler flags, but I cant remember that offhand.


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