See readme.txt for a general introduction, copyright details, and information about how to install Allegro and link your program with it.
The available system ID codes will vary from one platform to another, but you will almost always want to pass SYSTEM_AUTODETECT. Alternatively, SYSTEM_NONE installs a stripped down version of Allegro that won't even try to touch your hardware or do anything platform specific: this can be useful for situations where you only want to manipulate memory bitmaps, such as the text mode datafile tools or the Windows GDI interfacing functions.
The `errno_ptr' and `atexit_ptr' parameters should point to the errno variable and atexit function from your libc: these are required because when Allegro is linked as a DLL, it doesn't have direct access to your local libc data. `atexit_ptr' may be NULL, in which case it is your responsibility to call allegro_exit() manually. Example:
install_allegro(SYSTEM_AUTODETECT, &errno, atexit);
Return value: This function returns zero on success and non-zero on failure (e.g. no system driver could be used). Note: in previous versions of Allegro this function would abort on error.
See also: allegro_init, allegro_exit, set_uformat.
See also: install_allegro, allegro_exit.
Examples using this: Available Allegro examples.
Note that after you call this function, other functions like destroy_bitmap() will most likely crash. This is a problem for C++ global destructors, which usually get called after atexit(), so don't put Allegro calls in them. You can write the destructor code in another method which you can manually call before your program exits, avoiding this problem.
See also: install_allegro, allegro_init, destroy_bitmap.
Examples using this: ex3d, exscn3d, exswitch, exxfade, exzbuf.
int main(void) { allegro_init(); /* more stuff goes here */ ... return 0; } END_OF_MAIN()
See also: Windows specifics, Unix specifics, MacOS X specifics, Differences between platforms.
Examples using this: Available Allegro examples.
See also: set_gfx_mode, install_sound.
Examples using this: Available Allegro examples.
OSTYPE_UNKNOWN - unknown, or regular MSDOS OSTYPE_WIN3 - Windows 3.1 or earlier OSTYPE_WIN95 - Windows 95 OSTYPE_WIN98 - Windows 98 OSTYPE_WINME - Windows ME OSTYPE_WINNT - Windows NT OSTYPE_WIN2000 - Windows 2000 OSTYPE_WINXP - Windows XP OSTYPE_OS2 - OS/2 OSTYPE_WARP - OS/2 Warp 3 OSTYPE_DOSEMU - Linux DOSEMU OSTYPE_OPENDOS - Caldera OpenDOS OSTYPE_LINUX - Linux OSTYPE_SUNOS - SunOS/Solaris OSTYPE_FREEBSD - FreeBSD OSTYPE_NETBSD - NetBSD OSTYPE_IRIX - IRIX OSTYPE_DARWIN - Darwin OSTYPE_QNX - QNX OSTYPE_UNIX - Unknown Unix variant OSTYPE_BEOS - BeOS OSTYPE_MACOS - MacOS OSTYPE_MACOSX - MacOS X
See also: allegro_init, os_version, os_multitasking.
See also: os_type, os_multitasking.
See also: os_type, os_version.
Examples using this: exdodgy.
ret = allegro_init(); if (ret != 0) { allegro_message("Sorry, couldn't init Allegro (%d).\n", ret); exit(ret); }
See also: set_uformat.
Examples using this: Available Allegro examples.
See also: set_close_button_callback, set_uformat.
Examples using this: exunicod.
This function should not generally attempt to exit the program or save any data itself. The function could be called at any time, and there is usually a risk of conflict with the main thread of the program. Instead, you should set a flag during this function, and test it on a regular basis in the main loop of the program.
Pass NULL as the `proc' argument to this function to disable the close button functionality, which is the default state.
Note that Allegro cannot intercept the close button of a DOS box in Windows.
Return value: Returns zero on success and non-zero on failure (e.g. the feature is not supported by the platform).
See also: set_window_title.
Under some OSes, switching to a full screen graphics mode may automatically change the desktop color depth. You have, therefore, to call this function before setting any graphics mode in order to retrieve the real desktop color depth. Example:
allegro_init(); ... if ((depth = desktop_color_depth()) != 0) { set_color_depth(depth); }
Return value: Returns the color depth or zero on platforms where this information is not available or does not apply.
See also: get_desktop_resolution, set_color_depth, set_gfx_mode.
Under some OSes, switching to a full screen graphics mode may automatically change the desktop resolution. You have, therefore, to call this function before setting any graphics mode in order to retrieve the real desktop resolution. Example:
int width, height; allegro_init(); ... if (get_desktop_resolution(&width, &height) == 0) { /* Got the resolution correctly */ }
Return value: Returns zero on success, or a negative number if this information is not available or does not apply, in which case the values stored in the variables you provided for `width' and `height' are undefined.
See also: desktop_color_depth, set_gfx_mode.
Note that calling this inside your active game loop is a very bad idea, you never know when the OS will give you the CPU back, so you could end up missing the vertical retrace and skipping frames.
See also: vsync.
See also: cpu_vendor, cpu_family, cpu_model, cpu_capabilities, allegro_init.
See also: check_cpu, cpu_family, cpu_model, cpu_capabilities, allegro_init.
See also: check_cpu, cpu_vendor, cpu_model, cpu_capabilities, allegro_init.
See also: check_cpu, cpu_vendor, cpu_family, cpu_capabilities, allegro_init.
You can check for multiple features by OR-ing the flags together. For example, to check if the CPU has an FPU and MMX instructions available, you'd do:CPU_ID - Indicates that the "cpuid" instruction is available. If this is set, then all Allegro CPU variables are 100% reliable, otherwise there may be some mistakes. CPU_FPU - An x87 FPU is available. CPU_MMX - Intel MMX instruction set is available. CPU_MMXPLUS - Intel MMX+ instruction set is available. CPU_SSE - Intel SSE instruction set is available. CPU_SSE2 - Intel SSE2 instruction set is available. CPU_3DNOW - AMD 3DNow! instruction set is available. CPU_ENH3DNOW - AMD Enhanced 3DNow! instruction set is available. CPU_CMOV - Pentium Pro "cmov" instruction is available.
You can read this variable after you have called check_cpu() (which is automatically called by allegro_init()).if ((cpu_capabilities & (CPU_FPU | CPU_MMX)) == (CPU_FPU | CPU_MMX)) { printf("CPU has both an FPU and MMX instructions!\n"); }
See also: check_cpu, cpu_vendor, cpu_family, cpu_model, cpu_capabilities, allegro_init.