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<center><h1><b>
The Allegro FAQ<br>
<i>If the answer isn't here, ask and it will be added...</i></b></h1></center>
<hr>
<p>
<h1><a name="Contents">Contents</a></h1>
<p>
<ul>
<li><a href="#Trivial problems">Trivial problems</a>
<ul>
<li><a href="#How_do_I_use_it_"> How do I use it?</a>
<li><a href="#What_is_Allegro_"> What is Allegro?</a>
<li><a href="#Where_can_I_get_it_"> Where can I get it?</a>
</ul>
<li><a href="#The giftware licence">The giftware licence</a>
<ul>
<li><a href="#Can_I_use_Allegro_for_commercial_purposes_"> Can I use Allegro for commercial purposes?</a>
<li><a href="#Does_the_licence_mean_that_Allegro_is_public_domain_"> Does the licence mean that Allegro is public domain?</a>
<li><a href="#How_are_modifications_of_the_library_licensed_"> How are modifications of the library licensed?</a>
<li><a href="#I_took_your_code__Will_you_sue_me_"> I took your code. Will you sue me?</a>
<li><a href="#Is_Allegro_compatible_with_licence_XXX__e_g__GPL__"> Is Allegro compatible with licence XXX (e.g. GPL)?</a>
<li><a href="#Is_Allegro_open_source__OSI__compatible_"> Is Allegro open source (OSI) compatible?</a>
</ul>
<li><a href="#DJGPP problems">DJGPP problems</a>
<ul>
<li><a href="#Compile_errors_scroll_off_the_screen_too_quickly_for_me_to_read_them_"> Compile errors scroll off the screen too quickly for me to read them!</a>
<li><a href="#I_give_up__I_can_t_compile_this__Can_you_send_me_a_precompiled_version_"> I give up: I can't compile this! Can you send me a precompiled version?</a>
<li><a href="#Make_doesn_t_work_properly_"> Make doesn't work properly.</a>
<li><a href="#My_djgpp_installation_is_fine__but_make_still_doesn_t_work_properly_"> My djgpp installation is fine, but make still doesn't work properly.</a>
<li><a href="#What_is_this_make_program_that_I_m_supposed_to_run_"> What is this make program that I'm supposed to run?</a>
<li><a href="#When_I_run_make__it_asks_me_for_some_parameters__What_do_I_type_"> When I run make, it asks me for some parameters. What do I type?</a>
<li><a href="#When_I_run_make__it_says__conflicting_types_for_va_list__"> When I run make, it says "conflicting types for va_list".</a>
<li><a href="#When_I_run_make__it_says__makefile_has_modification_time_in_the_future__"> When I run make, it says "makefile has modification time in the future".</a>
<li><a href="#When_I_run_make__it_says__virtual_memory_exhausted__"> When I run make, it says "virtual memory exhausted".</a>
<li><a href="#When_I_try_to_compile_a_program_using_Allegro__I_get_lots_of_errors_like_"> When I try to compile a program using Allegro, I get lots of errors like:</a>
</ul>
<li><a href="#DOS problems">DOS problems</a>
<ul>
<li><a href="#Does_Allegro_work_under_OpenDOS_"> Does Allegro work under OpenDOS?</a>
<li><a href="#Does_DOS_Allegro_work_with_the_SB_Live_soundcard_"> Does DOS Allegro work with the SB-Live soundcard?</a>
<li><a href="#Does_the_DOS_version_of_Allegro_work_under_Windows_NT_"> Does the DOS version of Allegro work under Windows NT?</a>
<li><a href="#How_can_I_extend_the_256k_limit_on_Mode_X_video_memory_"> How can I extend the 256k limit on Mode-X video memory?</a>
<li><a href="#I_get_an__out_of_environment_space__error_when_I_run_fix_bat_or"> I get an "out of environment space" error when I run fix.bat or</a>
<li><a href="#Why_does_DOS_Allegro_play_sounds_so_much_quieter_than_in_Windows_"> Why does DOS Allegro play sounds so much quieter than in Windows?</a>
<li><a href="#Why_doesn_t_it_work_with_my_video_card_"> Why doesn't it work with my video card?</a>
<li><a href="#Why_not_use_some_sort_of_dynamic_linking_system_"> Why not use some sort of dynamic linking system?</a>
</ul>
<li><a href="#Windows problems">Windows problems</a>
<ul>
<li><a href="#I_get_an__out_of_environment_space__error_when_I_run_fix_bat_or"> I get an "out of environment space" error when I run fix.bat or</a>
<li><a href="#I_get_an_error_about_a_missing_WinMain___or_main___function_"> I get an error about a missing WinMain() or main() function!</a>
<li><a href="#I_get_an_error_about_an__unresolved_external_symbol__main__"> I get an error about an "unresolved external symbol _main"!</a>
<li><a href="#I_get_lots_of_compile_errors_about_conflicting_types_for__struct_BITMAP__"> I get lots of compile errors about conflicting types for "struct BITMAP"!</a>
<li><a href="#I_get_lots_of_compile_errors_about_things_like__DDEDM_STANDARDVGAMODES__"> I get lots of compile errors about things like "DDEDM_STANDARDVGAMODES"!</a>
<li><a href="#I_get_lots_of_compile_errors_about_things_like__LPDIRECTDRAWSURFACE2__"> I get lots of compile errors about things like "LPDIRECTDRAWSURFACE2"!</a>
<li><a href="#In_windowed_mode_artifacts_are_left_on_the_desktop_when_the_window"> In windowed mode artifacts are left on the desktop when the window</a>
<li><a href="#In_windowed_mode_the_screen_stays_black_unless_the_window_is_placed"> In windowed mode the screen stays black unless the window is placed</a>
<li><a href="#When_I_run_make__it_says__missing_separator__"> When I run make, it says "missing separator".</a>
<li><a href="#When_I_run_make__it_says__windres__no_resources__"> When I run make, it says "windres: no resources".</a>
</ul>
<li><a href="#Unix problems">Unix problems</a>
<ul>
<li><a href="#Compile_errors_scroll_off_the_screen_way_too_quickly_for_me_to_read_them_"> Compile errors scroll off the screen way too quickly for me to read them!</a>
<li><a href="#I_get_an_error_about___mangled_main_address__being_undefined_"> I get an error about "_mangled_main_address" being undefined!</a>
<li><a href="#I_get_an_error_about_a_duplicate_definition_of_the___main__symbol_"> I get an error about a duplicate definition of the "_main" symbol!</a>
<li><a href="#When_I_try_to_run_Allegro_programs__I_get__error_while_loading_shared_libraries_"> When I try to run Allegro programs, I get "error while loading shared libraries:</a>
<li><a href="#When_I_try_to_use_DGA2__I_get__resolution_not_supported___but_the"> When I try to use DGA2, I get "resolution not supported", but the</a>
<li><a href="#When_I_try_to_use_DGA2__the_screen_goes_black_and_the_PC_completely"> When I try to use DGA2, the screen goes black and the PC completely</a>
</ul>
<li><a href="#General problems">General problems</a>
<ul>
<li><a href="#Can_I_use_Allegro_in_my__ltwhatever_gt_commercial_application_"> Can I use Allegro in my <whatever> commercial application?</a>
<li><a href="#Can_I_use_Allegro_with_my__ltfoobar_gt_compiler_"> Can I use Allegro with my <foobar> compiler?</a>
<li><a href="#How_can_I_convert_my_graphics_to_all_use_the_same_256_color_palette_"> How can I convert my graphics to all use the same 256 color palette?</a>
<li><a href="#How_can_I_convert_the_documentation_into_Windows_Help_format_"> How can I convert the documentation into Windows Help format?</a>
<li><a href="#How_can_I_display_several_different_images_at_the_same_time_"> How can I display several different images at the same time?</a>
<li><a href="#How_can_I_fade_the_screen_in_a_truecolor_graphics_mode_"> How can I fade the screen in a truecolor graphics mode?</a>
<li><a href="#How_can_I_generate_a_random_number_"> How can I generate a random number?</a>
<li><a href="#How_can_I_generate_FLI_or_FLC_format_animations_"> How can I generate FLI or FLC format animations?</a>
<li><a href="#How_can_I_make_my_game_run_at_the_same_speed_on_any_computer_"> How can I make my game run at the same speed on any computer?</a>
<li><a href="#How_can_I_make_parts_of_my_sprite_transparent_in_truecolor_modes_"> How can I make parts of my sprite transparent in truecolor modes?</a>
<li><a href="#How_can_I_print_out_the_documentation_"> How can I print out the documentation?</a>
<li><a href="#How_can_I_take_a_screenshot_of_my_Allegro_program_"> How can I take a screenshot of my Allegro program?</a>
<li><a href="#I_can_t_get_the_3D_polygon_functions_to_work_"> I can't get the 3D polygon functions to work!</a>
<li><a href="#I_can_t_get_the_d_bitmap_proc___or_d_icon_proc___GUI_object_to_work_"> I can't get the d_bitmap_proc() or d_icon_proc() GUI object to work!</a>
<li><a href="#I_can_t_get_the_rotate_sprite___function_to_work_"> I can't get the rotate_sprite() function to work!</a>
<li><a href="#I_get_lots_of_errors_when_I_try_to_compile_my_C___Allegro_program_"> I get lots of errors when I try to compile my C++ Allegro program.</a>
<li><a href="#I_got_the_WIP_patch__but_I_can_t_apply_it_"> I got the WIP patch, but I can't apply it.</a>
<li><a href="#I_m_still_confused__Where_can_I_get_help_"> I'm still confused. Where can I get help?</a>
<li><a href="#I_m_trying_to_compile_the_grabber__but_it_doesn_t_work_"> I'm trying to compile the grabber, but it doesn't work!</a>
<li><a href="#I_tried_using_fade_in___and_fade_out___with_truecolor_modes_but_nothing"> I tried using fade_in() and fade_out() with truecolor modes but nothing</a>
<li><a href="#My_colors_always_come_out_wrong__And_how_can_I_make_a_greyscale_palette"> My colors always come out wrong. And how can I make a greyscale palette</a>
<li><a href="#My_program_crashes_all_the_time__Could_this_be_a_bug_in_Allegro_"> My program crashes all the time. Could this be a bug in Allegro?</a>
<li><a href="#Should_I_use_regular_bitmaps__RLE_sprites__or_compiled_sprites_"> Should I use regular bitmaps, RLE sprites, or compiled sprites?</a>
<li><a href="#What_is_this__Allegro_WIP__that_I_see_people_talking_about_"> What is this "Allegro WIP" that I see people talking about?</a>
<li><a href="#When_I_compile_Allegro__make_fails_with_something_like__Error__operands"> When I compile Allegro, make fails with something like `Error: operands</a>
<li><a href="#When_I_run_the_demo_game__it_says_it_can_t_find_demo_dat_"> When I run the demo game, it says it can't find demo.dat.</a>
<li><a href="#When_will__ltfoobar_gt_be_finished__I_can_t_wait___"> When will <foobar> be finished? I can't wait...</a>
<li><a href="#Where_can_I_find_a_set_of_instrument_samples_for_the_DIGMID_driver_"> Where can I find a set of instrument samples for the DIGMID driver?</a>
<li><a href="#Where_can_I_find_example_source_code__add_on_packages__and_tutorials_"> Where can I find example source code, add-on packages, and tutorials?</a>
<li><a href="#Where_can_I_get_some_fonts_to_use_with_Allegro_"> Where can I get some fonts to use with Allegro?</a>
<li><a href="#Why_can_t_Allegro_read_GIF_files_"> Why can't Allegro read GIF files?</a>
<li><a href="#Why_do_I_have_a_funny_color_border_at_the_edges_of_my_monitor_"> Why do I have a funny color border at the edges of my monitor?</a>
<li><a href="#Why_doesn_t_busy_waiting_on_the_key_array_work__For_example_"> Why doesn't busy waiting on the key array work? For example,</a>
<li><a href="#Why_doesn_t_vsync___seem_to_work_"> Why doesn't vsync() seem to work?</a>
<li><a href="#Why_is_it_considered_good_coding_practice_to_define_PI_as_a_constant_"> Why is it considered good coding practice to define PI as a constant,</a>
<li><a href="#Why_not_add_a_MOD_playing_function_"> Why not add a MOD playing function?</a>
<li><a href="#Why_not_add_networking_support_"> Why not add networking support?</a>
<li><a href="#Why_not_make_a__lite__version_of_Allegro_"> Why not make a "lite" version of Allegro?</a>
<li><a href="#Will_you_ever_add_support_for_3D_accelerator_hardware_"> Will you ever add support for 3D accelerator hardware?</a>
</ul>
</ul>
<p><br>
<h1><a name="Trivial problems">Trivial problems</a></h1>
<div class="faq-shift-to-right">
<p><br>
<div class="al-api"><b><a name="What_is_Allegro_"> What is Allegro?</a></b></div><br>
See <tt><a href="readme.html">readme.txt</a></tt>.
<p><br>
<div class="al-api"><b><a name="Where_can_I_get_it_"> Where can I get it?</a></b></div><br>
From any SimTel mirror (<a href="http://alleg.sourceforge.net/mirrors.html">http://alleg.sourceforge.net/mirrors.html</a>), in
the directory <tt>gnu/djgpp/v2tk/</tt>, or from the Allegro homepage,
<a href="http://alleg.sourceforge.net/">http://alleg.sourceforge.net/</a>.
<p><br>
<div class="al-api"><b><a name="How_do_I_use_it_"> How do I use it?</a></b></div><br>
See <tt><a href="allegro.html">allegro.txt</a></tt>.
</div>
<p><br>
<h1><a name="The giftware licence">The giftware licence</a></h1>
<p>
The Allegro licence is absolutely clear unless you are a lawyer.
However, it's written quite informally so this mini-FAQ tries to clarify
some things.
<div class="faq-shift-to-right">
<p><br>
<div class="al-api"><b><a name="Does_the_licence_mean_that_Allegro_is_public_domain_"> Does the licence mean that Allegro is public domain?</a></b></div><br>
No. Every Allegro contributor holds the copyright for the code he or
she wrote. This means he or she grants you the right to use it for
any purpose you want. But the fact that the contributor holds the
copyright means that you e.g. cannot claim that you wrote the code.
<p><br>
<div class="al-api"><b><a name="Can_I_use_Allegro_for_commercial_purposes_"> Can I use Allegro for commercial purposes?</a></b></div><br>
Yes.
<p><br>
<div class="al-api"><b><a name="Is_Allegro_compatible_with_licence_XXX__e_g__GPL__"> Is Allegro compatible with licence XXX (e.g. GPL)?</a></b></div><br>
Because the Allegro licence has no restrictions on use you can combine
it with any licence you want.
<p><br>
<div class="al-api"><b><a name="Is_Allegro_open_source__OSI__compatible_"> Is Allegro open source (OSI) compatible?</a></b></div><br>
See the previous question. Since Allegro is compatible with about any
license, it also is OSI compatible. It clearly is compatible with all the
points in the OSD (open source definition). You can search the OSI
mailing list for "Allegro" to see that OSI shares this view. (OSI
officials still were reluctant to consider it for approval though and
suggested to use an existing license like MIT instead.)
<p><br>
<div class="al-api"><b><a name="How_are_modifications_of_the_library_licensed_"> How are modifications of the library licensed?</a></b></div><br>
You can modify Allegro and distribute the modified Allegro under
any licence you want, but the original unmodified parts will still
be licenced under the Allegro licence. If you offer your
modifications to be included in the official Allegro distribution
(e.g. by sending them to the Allegro developers mailing list) you
automatically agree with licencing the modification under the
Allegro licence.
<p><br>
<div class="al-api"><b><a name="I_took_your_code__Will_you_sue_me_"> I took your code. Will you sue me?</a>
Your library destroyed my PC. Who do I sue?</b></div><br>
We are programmers not lawyers. This FAQ represents our current
understanding of copyright law (or copyright laws in different
countries). But given the license, which allows everything, and
the disclaimer, which says we take no responsibility for anything,
we really don't see how there could be any problems.
</div>
<p><br>
<h1><a name="DJGPP problems">DJGPP problems</a></h1>
<div class="faq-shift-to-right">
<p><br>
<div class="al-api"><b><a name="What_is_this_make_program_that_I_m_supposed_to_run_"> What is this make program that I'm supposed to run?</a></b></div><br>
Make is part of the standard djgpp distribution, in the file
<tt>v2gnu/mak*b.zip</tt> (whatever the latest version number is).
You can get this from <a href="http://www.delorie.com/djgpp/">http://www.delorie.com/djgpp/</a>.
<p><br>
<div class="al-api"><b><a name="Make_doesn_t_work_properly_"> Make doesn't work properly.</a></b></div><br>
Are you sure that you have installed djgpp correctly? Check the
instructions in the djgpp <tt>readme.1st</tt> file, and in particular confirm
that you have set the DJGPP environment variable and added the
<tt>djgpp\bin</tt> directory to your path.
<p><br>
<div class="al-api"><b><a name="My_djgpp_installation_is_fine__but_make_still_doesn_t_work_properly_"> My djgpp installation is fine, but make still doesn't work properly.</a></b></div><br>
Are you sure that you are using the GNU make program, and not some
other version like the Borland one? If in doubt, run <tt>make -v</tt> and
check that the GNU copyright message is displayed.
<p><br>
<div class="al-api"><b><a name="When_I_run_make__it_asks_me_for_some_parameters__What_do_I_type_"> When I run make, it asks me for some parameters. What do I type?</a></b></div><br>
You shouldn't be running make from the Win95 explorer! Bring up a DOS
box, change to your Allegro directory, and type <tt>make</tt> at the command
prompt.
<p><br>
<div class="al-api"><b><a name="When_I_run_make__it_says__makefile_has_modification_time_in_the_future__"> When I run make, it says "makefile has modification time in the future".</a></b></div><br>
Are you sure that your system time and date are set correctly?
Alternatively you may have downloaded a fresh file made by someone in a
more eastern timezone. In the latter case you can either wait a few
hours, temporarily set your clock forward, or use a utility such as
<tt>touch</tt> to change the timestamp of the files.
<p><br>
<div class="al-api"><b><a name="When_I_run_make__it_says__virtual_memory_exhausted__"> When I run make, it says "virtual memory exhausted".</a></b></div><br>
<p>
As the error message suggests, you need to provide more memory for the
compiler to use. The <tt>go32-v2</tt> program will tell you how much is
currently available. If you are running under DOS, try to free up more
disk space for use as a swapfile. When using win95, increase the DPMI
memory limit in the properties for your DOS session to 65535 (you'll
have to type this in by hand, because the pulldown list doesn't go
above 16384).
<p><br>
<div class="al-api"><b><a name="When_I_run_make__it_says__conflicting_types_for_va_list__"> When I run make, it says "conflicting types for va_list".</a></b></div><br>
<p>
As the error message suggests, there is a conflict between newer
versions of gcc and older versions of the libc. You must upgrade your
djdevxxx.zip package to the latest update (timestamp 11 August 2002)
of DJGPP-2.03 or above.
<p><br>
<div class="al-api"><b><a name="When_I_try_to_compile_a_program_using_Allegro__I_get_lots_of_errors_like_"> When I try to compile a program using Allegro, I get lots of errors like:</a></b></div><br>
C:\TEMP\ccdaaaaa(.text+0x9):x.c: undefined reference to <tt>`allegro_init'</tt><br>
C:\TEMP\ccdaaaaa(.text+0xe):x.c: undefined reference to <tt>`install_keyboard'</tt><br>
<p>
You haven't read the docs, have you? :-) You need to link your program
with the library file, <tt>liballeg.a</tt>. First, make sure you have installed
everything properly (running <tt>make install</tt> should do this for you).
Second, if you are compiling from the command prompt or with a makefile,
add <tt>-lalleg</tt> to the end of your gcc command line, or if you are using Rhide,
go to the Options/Libraries menu, type <tt>alleg</tt> into the first empty field,
and make sure the box next to it is checked.
<p><br>
<div class="al-api"><b><a name="I_give_up__I_can_t_compile_this__Can_you_send_me_a_precompiled_version_"> I give up: I can't compile this! Can you send me a precompiled version?</a></b></div><br>
<p>
No, sorry. For starters, <tt>liballeg.a</tt> is about 450k, but you'd probably
also want various utilities like the grabber, sound setup, etc. And
what about all the example programs? If we included compiled versions
of everything, a binary distribution would be over 7 megs: way too big
to be practical! More seriously though, there just isn't any reason
why you can't build it yourself. A compiler is a deterministic
process: given a particular input file and command line, it will always
produce the same output. If this isn't working, you either have the
wrong input files (ie. your copy of Allegro is broken in some way), or
the wrong command line (it is hard to see how that could happen, since
all you have to do is type <tt>make</tt>...) or your compiler is broken, ie. you
didn't install djgpp properly. You need to find and fix the problem,
not just sweep it under the carpet by getting someone else to compile
Allegro for you...
<p><br>
<div class="al-api"><b><a name="Compile_errors_scroll_off_the_screen_too_quickly_for_me_to_read_them_"> Compile errors scroll off the screen too quickly for me to read them!</a></b></div><br>
<p>
GNU tools write their error messages to the error stream, <tt>stderr</tt>.
Unfortunately <tt>command.com</tt> is too stupid to know how to redirect this,
but fortunately DJ was smart enough to work around that, so you can
use his redir program to capture the output messages, for example
<pre>
redir -eo make > logfile.txt
</pre>
</div>
<p><br>
<h1><a name="DOS problems">DOS problems</a></h1>
<div class="faq-shift-to-right">
<p><br>
<div class="al-api"><b><a name="Does_the_DOS_version_of_Allegro_work_under_Windows_NT_"> Does the DOS version of Allegro work under Windows NT?</a></b></div><br>
<p>
Your mileage may vary. Some people have reported problems, while
others say that it works fine. Use the Windows version of Allegro
if you want to make Windows programs. If you want to run DOS
programs, use DOS!
<p><br>
<div class="al-api"><b><a name="Does_Allegro_work_under_OpenDOS_"> Does Allegro work under OpenDOS?</a></b></div><br>
<p>
Yes, but with some caveats. If you are using the OpenDOS version of
EMM386, you must disable their DPMI implementation (specify <tt>DPMI=OFF</tt>
on the <tt>EMM386.EXE</tt> device line in your config.sys). You should also
make sure the <tt>PIC=OFF</tt> flag is set, but this is the default so it won't
be a problem unless you have specifically enabled it.
<p><br>
<div class="al-api"><b><a name="How_can_I_extend_the_256k_limit_on_Mode_X_video_memory_"> How can I extend the 256k limit on Mode-X video memory?</a>
I have two megs in my card.</b></div><br>
<p>
You can't. The limit is imposed by the VGA hardware, not by Allegro.
To access more than 256k of video memory you need to use an SVGA mode,
which means either switching to a higher resolution or getting a copy
of the SciTech Display Doctor, which provides several low resolution
SVGA modes.
<p><br>
<div class="al-api"><b><a name="Does_DOS_Allegro_work_with_the_SB_Live_soundcard_"> Does DOS Allegro work with the SB-Live soundcard?</a></b></div><br>
<p>
It does for some people, but not for others. The problem is that
Creative Labs refuse to release any specs, so we don't know how to
write a driver for it. Complain to them, or buy a different card from
a more reasonable manufacturer.
<p><br>
<div class="al-api"><b><a name="Why_does_DOS_Allegro_play_sounds_so_much_quieter_than_in_Windows_"> Why does DOS Allegro play sounds so much quieter than in Windows?</a></b></div><br>
<p>
This might be because you have the volume set very low: try changing
this in the setup program. Also, Allegro is mixing several sounds into
a single output buffer, unlike the Windows sound player that only
plays one sample at a time, so each individual sound can only get a
smaller percentage of the total output volume. This is just the price
you pay for multiple output channels. If you don't like it, use the
setup program to tweak the number of channels: this can be any power
of two less than or equal to 64, and the smaller you make it, the
louder the sound will be. Alternatively, use <code>set_volume_per_voice()</code>,
described in the docs. This will enable you to adjust the overall
volume of Allegro's digital sound output.
<p><br>
<div class="al-api"><b><a name="Why_doesn_t_it_work_with_my_video_card_"> Why doesn't it work with my video card?</a></b></div><br>
<p>
Try using a FreeBE/AF driver (<a href="http://www.talula.demon.co.uk/freebe/">http://www.talula.demon.co.uk/freebe/</a>),
or the commercial SciTech Display Doctor (<a href="http://www.scitechsoft.com">http://www.scitechsoft.com</a>).
If it still doesn't work, post a description of your problem to the
Allegro mailing list, along with a copy of the output from running the
afinfo and vesainfo programs.
<p><br>
<div class="al-api"><b><a name="Why_not_use_some_sort_of_dynamic_linking_system_"> Why not use some sort of dynamic linking system?</a></b></div><br>
<p>
The VBE/AF interface already provides this for the video drivers: see
the FreeBE/AF project on <a href="http://www.talula.demon.co.uk/freebe/">http://www.talula.demon.co.uk/freebe/</a>.
For more general things like the sound, VESA, and mode-X routines,
this would be very difficult to do because the drivers depend on a lot
of helper functions from the core lib. The djgpp DXE format is nowhere
near flexible enough to support this, and we don't want to make Allegro
dependent on any other dynamic linking packages.
<p><br>
<div class="al-api"><b><a name="I_get_an__out_of_environment_space__error_when_I_run_fix_bat_or"> I get an "out of environment space" error when I run fix.bat or</a>
vcvars32.bat!</b></div><br>
<p>
Well duh, you need to increase the size of your environment then :-)
You can do this by changing the settings for your DOS box (click the
system menu and select "properties"), or at startup in your config.sys
file (eg. <tt>shell=c:\command.com /e:8192 /p</tt>).
</div>
<p><br>
<h1><a name="Windows problems">Windows problems</a></h1>
<div class="faq-shift-to-right">
<p><br>
<div class="al-api"><b><a name="I_get_an__out_of_environment_space__error_when_I_run_fix_bat_or"> I get an "out of environment space" error when I run fix.bat or</a>
vcvars32.bat!</b></div><br>
<p>
Well duh, you need to increase the size of your environment then :-)
You can do this by changing the settings for your DOS box (click the
system menu and select "properties"), or at startup in your config.sys
file (eg. <tt>shell=c:\command.com /e:8192 /p</tt>).
<p><br>
<div class="al-api"><b><a name="When_I_run_make__it_says__missing_separator__"> When I run make, it says "missing separator".</a></b></div><br>
<p>
Make sure that you don't have a semi-colon appended to your MSVCDIR
variable if you are using MSVC, to your MINGDIR variable if you are
using MinGW or to your BCC32DIR variable if you are using BCC.
Also run <tt>make -v</tt> from the command line and make sure you are using
GNU make and not Borland make or Microsoft make.
<p><br>
<div class="al-api"><b><a name="I_get_lots_of_compile_errors_about_things_like__LPDIRECTDRAWSURFACE2__"> I get lots of compile errors about things like "LPDIRECTDRAWSURFACE2"!</a></b></div><br>
<p>
You need to tell your compiler how to find the DirectX include files
and libraries: put the DirectX SDK <tt>/include</tt> and <tt>/lib</tt> directories in the
compiler/linker path. Alternatively, if you don't want to modify any
configuration stuff, you can simply copy the files from the DirectX SDK
<tt>/include</tt> and <tt>/lib</tt> directories to the corresponding ones for your
compiler.
<p><br>
<div class="al-api"><b><a name="I_get_lots_of_compile_errors_about_things_like__DDEDM_STANDARDVGAMODES__"> I get lots of compile errors about things like "DDEDM_STANDARDVGAMODES"!</a></b></div><br>
<p>
You need to upgrade to a more recent version of the DirectX SDK, at
least version 5, which you can get from the Microsoft Developer site.
<p><br>
<div class="al-api"><b><a name="When_I_run_make__it_says__windres__no_resources__"> When I run make, it says "windres: no resources".</a></b></div><br>
<p>
If an anti-virus software (Norton or McAfee for example) is running in
the background on your computer, try to disable it temporarily.
<p><br>
<div class="al-api"><b><a name="I_get_an_error_about_a_missing_WinMain___or_main___function_"> I get an error about a missing WinMain() or main() function!</a></b></div><br>
<p>
You need to write <code>END_OF_MAIN()</code> just after your <code>main()</code> function.
Allegro uses this, along with some preprocessor magic, to turn a normal
<code>main()</code> function into a Windows-style <code>WinMain()</code> entry point.
<p><br>
<div class="al-api"><b><a name="I_get_an_error_about_an__unresolved_external_symbol__main__"> I get an error about an "unresolved external symbol _main"!</a></b></div><br>
<p>
Make sure you're building a Windows GUI Application, and not a Windows
Console Application. This is a setting when you create the project in
MSVC, Dev-C++ or Borland C++ Builder. Alternatively, this is specified
on the command line by the <tt>-subsystem:windows</tt> option for the MSVC
linker, by the <tt>-Wl,--subsystem,windows</tt> option for the MinGW compiler
or the <tt>-tW</tt> option for the Borland C++ compiler. Either that, or define
the preprocessor symbol <tt>ALLEGRO_USE_CONSOLE</tt> prior to including Allegro
headers if you really need the console for your program.
<p><br>
<div class="al-api"><b><a name="I_get_lots_of_compile_errors_about_conflicting_types_for__struct_BITMAP__"> I get lots of compile errors about conflicting types for "struct BITMAP"!</a></b></div><br>
<p>
If your program directly includes Win32 API header files, see the
"Windows specifics" section of the documentation.
<p>
<p>
If your program only includes header files of the C++ standard library,
you're very likely trying to compile it with gcc 3.x for MinGW; if so,
define the symbol <tt>__GTHREAD_HIDE_WIN32API</tt> on the compiler command line:
<pre>
g++ -D__GTHREAD_HIDE_WIN32API program.cpp -lalleg
</pre>
<p><br>
<div class="al-api"><b><a name="In_windowed_mode_artifacts_are_left_on_the_desktop_when_the_window"> In windowed mode artifacts are left on the desktop when the window</a>
is moved or when another window is placed on top of it.</b></div><br>
<p>
Disable direct updating for the DirectX windowed driver by using the
dedicated configuration variable. See the 'Configuration routines'
section in the docs and the <tt>allegro.cfg</tt> template file for more
detailed informations.
<p><br>
<div class="al-api"><b><a name="In_windowed_mode_the_screen_stays_black_unless_the_window_is_placed"> In windowed mode the screen stays black unless the window is placed</a>
under another window on the desktop.</b></div><br>
<p>
Disable direct updating for the DirectX windowed driver by using the
dedicated configuration variable. See the 'Configuration routines'
section in the docs and the <tt>allegro.cfg</tt> template file for more
detailed informations.
</div>
<p><br>
<h1><a name="Unix problems">Unix problems</a></h1>
<div class="faq-shift-to-right">
<p><br>
<div class="al-api"><b><a name="I_get_an_error_about___mangled_main_address__being_undefined_"> I get an error about "_mangled_main_address" being undefined!</a></b></div><br>
<p>
You need to write <code>END_OF_MAIN()</code> just after your <code>main()</code> function.
Allegro uses this, along with some preprocessor magic, to get a copy
of your <code>argv[]</code> parameters (it needs those for various internal things).
<p><br>
<div class="al-api"><b><a name="I_get_an_error_about_a_duplicate_definition_of_the___main__symbol_"> I get an error about a duplicate definition of the "_main" symbol!</a></b></div><br>
<p>
You are probably on a Darwin/MacOS X system. If so, make sure the symbol
<code>USE_CONSOLE</code> is not defined in your program: it is a deprecated symbol
that must be replaced by <code>ALLEGRO_USE_CONSOLE</code>. Also note that the magic
main can't be disabled on such a system: you simply can't define the
symbol <code>ALLEGRO_NO_MAGIC_MAIN</code> in a program linked against Allegro.
<p><br>
<div class="al-api"><b><a name="Compile_errors_scroll_off_the_screen_way_too_quickly_for_me_to_read_them_"> Compile errors scroll off the screen way too quickly for me to read them!</a></b></div><br>
<p>
You need to redirect stderr into a file, so you can view them later.
The method for doing this depends on your shell: if you are using a
Bourne-style shell like bash, try <tt>make 2> logfile.txt</tt>
<p><br>
<div class="al-api"><b><a name="When_I_try_to_run_Allegro_programs__I_get__error_while_loading_shared_libraries_"> When I try to run Allegro programs, I get "error while loading shared libraries:</a>
liballeg.so.4.1: cannot open shared object file: No such file or directory".</b></div><br>
<p>
You need to teach the dynamic linker where to find the Allegro shared library.
See <tt>docs/build/unix.txt</tt>, near the end of the 'Installing Allegro' section.
<p><br>
<div class="al-api"><b><a name="When_I_try_to_use_DGA2__I_get__resolution_not_supported___but_the"> When I try to use DGA2, I get "resolution not supported", but the</a>
X server does actually support that resolution !</b></div><br>
<p>
There are two possible reasons:
1) DGA2 may support different resolutions/color depths than X,
run the gfxinfo program to know what combinations you can use,
2) You may have a buggy DGA2 implementation, see next question.
<p><br>
<div class="al-api"><b><a name="When_I_try_to_use_DGA2__the_screen_goes_black_and_the_PC_completely"> When I try to use DGA2, the screen goes black and the PC completely</a>
halts!</b></div><br>
<p>
You are probably using a XFree86 server with a very buggy DGA2
implementation, such as 4.0.3 (shipped with Red Hat 7.1 for example).
Upgrading to 4.1.0 will probably solve your problem. You can obtain
it from <a href="ftp://ftp.xfree86.org/pub/XFree86/4.1.0/binaries/">ftp://ftp.xfree86.org/pub/XFree86/4.1.0/binaries/</a> selecting
the directory suited to your platform and following the instructions
you find in the Install file.
</div>
<p><br>
<h1><a name="General problems">General problems</a></h1>
<div class="faq-shift-to-right">
<p><br>
<div class="al-api"><b><a name="I_m_trying_to_compile_the_grabber__but_it_doesn_t_work_"> I'm trying to compile the grabber, but it doesn't work!</a></b></div><br>
<p>
The grabber needs to be linked with the code in <code>datedit.c</code>. But you
shouldn't have to worry about doing this by hand: just run <code>make</code> and
that will build everything for you.
<p><br>
<div class="al-api"><b><a name="When_I_compile_Allegro__make_fails_with_something_like__Error__operands"> When I compile Allegro, make fails with something like `Error: operands</a>
given don't match any known 386 instruction' or `Error: no such
instruction `maskmovq %mm3, %mm1''.</b></div><br>
<p>
You need to update your version of GNU binutils. See <tt><a href="readme.html">readme.txt</a></tt> to
find out what the minimum required version you need is.
<p><br>
<div class="al-api"><b><a name="Can_I_use_Allegro_with_my__ltfoobar_gt_compiler_"> Can I use Allegro with my <foobar> compiler?</a></b></div><br>
<p>
Not unless <foobar> is mentioned in <tt><a href="readme.html">readme.txt</a></tt> as one of the
supported platforms. You could port it, but that is usually a lot of
work. If <foobar> is a 16 bit DOS compiler like Borland C, you
might as well just forget the idea :-)
<p><br>
<div class="al-api"><b><a name="What_is_this__Allegro_WIP__that_I_see_people_talking_about_"> What is this "Allegro WIP" that I see people talking about?</a></b></div><br>
<p>
WIP stands for "work in progress", and refers to any changes that are
more recent than the last official release. WIP versions of the
library can be obtained as patches from the Allegro website
(<a href="http://alleg.sourceforge.net/">http://alleg.sourceforge.net/</a>), and are usually
quite stable, although obviously not so well tested as a final release
version.
<p><br>
<div class="al-api"><b><a name="I_got_the_WIP_patch__but_I_can_t_apply_it_"> I got the WIP patch, but I can't apply it.</a></b></div><br>
<p>
Do you have a copy of <tt>patch.exe</tt>? If not, go and get it from the same
place that you downloaded the rest of djgpp: this tool is a standard
part of the compiler distribution. Similarly, you can get the Mingw
compiled version from <a href="http://sourceforge.net/projects/gnuwin32/">http://sourceforge.net/projects/gnuwin32/</a>.
<p>
<p>
If you do have the patch program but it isn't working properly, make
sure that you are installing the patch over the top of an unmodified
copy of whatever Allegro version it is intended to update (this will
usually be the most recent official release from before the WIP was
made, but check the text file that comes with the WIP to be sure).
<p><br>
<div class="al-api"><b><a name="When_I_run_the_demo_game__it_says_it_can_t_find_demo_dat_"> When I run the demo game, it says it can't find demo.dat.</a></b></div><br>
<p>
That file is distributed separately in the WIP versions. It is here:
<a href="http://alleg.sourceforge.net/wip.html">http://alleg.sourceforge.net/wip.html</a>. (<tt>alldata.zip</tt>)
<p><br>
<div class="al-api"><b><a name="How_can_I_display_several_different_images_at_the_same_time_"> How can I display several different images at the same time?</a>
When I show the second one it messes up the palette for the first.</b></div><br>
<p>
This is just the way that the video hardware works: there can only be
one palette in use at any given moment. Either convert your images so
they all use the same palette, or switch to a truecolor graphics mode.
<p><br>
<div class="al-api"><b><a name="How_can_I_convert_my_graphics_to_all_use_the_same_256_color_palette_"> How can I convert my graphics to all use the same 256 color palette?</a></b></div><br>
<p>
See the Allegro.cc homepage (<a href="http://www.allegro.cc/">http://www.allegro.cc/</a>)
for some utilities, for example FixPal and Smacker.
<p><br>
<div class="al-api"><b><a name="My_colors_always_come_out_wrong__And_how_can_I_make_a_greyscale_palette"> My colors always come out wrong. And how can I make a greyscale palette</a>
with 256 different shades?</b></div><br>
<p>
The VGA hardware only uses 6 bits for each color component, which
means the red, green, and blue values in the palette structure range
from 0 to 63, not all the way up to 255. That gives you a potential
2^18 = 262144 different colors, or 64 shades of grey. If you need more
than this you could try using VESA function <tt>0x4F08</tt> to select an 8 bit
wide DAC, but Allegro doesn't support this directly and I don't know
how reliable it will be across different hardware.
<p><br>
<div class="al-api"><b><a name="Why_do_I_have_a_funny_color_border_at_the_edges_of_my_monitor_"> Why do I have a funny color border at the edges of my monitor?</a></b></div><br>
<p>
When you are in a 256 color mode, the VGA card displays color #0
around the border of the display area (in truecolor modes it displays
black). Your funny color will go away if you change the palette so
that color #0 is black.
<p><br>
<div class="al-api"><b><a name="How_can_I_fade_the_screen_in_a_truecolor_graphics_mode_"> How can I fade the screen in a truecolor graphics mode?</a></b></div><br>
<p>
With great difficulty :-) There is no such easy trick as just altering
the palette, so you will have to repeatedly redraw the image in a
lighter or darker form. You could draw black translucent rectangles
over the screen to darken it down, or use <code>draw_lit_sprite()</code> to tint a
bitmap while copying it to the screen, but be warned that these
operations are expensive and will require a fast PC!
<p>
<p>
Also, have a look at <a href="http://www.allegro.cc/">http://www.allegro.cc/</a> for add-on packages
(notably FBlend v0.5) that attempt to make this operation as fast as
possible.
<p><br>
<div class="al-api"><b><a name="I_tried_using_fade_in___and_fade_out___with_truecolor_modes_but_nothing"> I tried using fade_in() and fade_out() with truecolor modes but nothing</a>
happened. What am I doing wrong?</b></div><br>
<p>
<code>fade_in()</code> and <code>fade_out()</code> only work in 8-bit paletted modes.
See the previous question for details.
<p><br>
<div class="al-api"><b><a name="How_can_I_generate_FLI_or_FLC_format_animations_"> How can I generate FLI or FLC format animations?</a></b></div><br>
<p>
See the Allegro.cc homepage (<a href="http://www.allegro.cc/">http://www.allegro.cc/</a>)
for some utilities, for example DTA and Smacker. Also, you can use ASE
(Allegro Sprite Editor, <a href="http://ase.sourceforge.net/">http://ase.sourceforge.net/</a>), which allows
drawing/editing each frame of the animation and save it as a FLI. Or
you can use The GIMP (<a href="http://www.gimp.org/">http://www.gimp.org/</a>) along with it's GFli
plugin, using layers as frames, and saving your work as <tt>file.fli</tt>.
The GIMP allows you to edit existent FLI files too.
<p><br>
<div class="al-api"><b><a name="How_can_I_make_parts_of_my_sprite_transparent_in_truecolor_modes_"> How can I make parts of my sprite transparent in truecolor modes?</a>
I don't understand what the docs mean by "bright pink"...</b></div><br>
<p>
In your favourite paint program, get hold of the RGB sliders and drag
the red and blue ones up as far as they go (usually to 255, but this
will depend on what units your software uses), and the green one right
down to zero. The result is a special shade of Magic Pink, or as some
people prefer to call it, magenta.
<p><br>
<div class="al-api"><b><a name="I_can_t_get_the_3D_polygon_functions_to_work_"> I can't get the 3D polygon functions to work!</a></b></div><br>
<p>
Remember that the vertex positions are stored in fixed point format,
so you must use the <code>itofix()</code> macro or shift your coordinates 16 bits
to the left.
<p><br>
<div class="al-api"><b><a name="I_can_t_get_the_rotate_sprite___function_to_work_"> I can't get the rotate_sprite() function to work!</a></b></div><br>
<p>
Remember that the angle of rotation is stored in fixed point format,
so you must use the <code>itofix()</code> macro or shift your coordinates 16 bits
to the left. For example, <code>rotate_sprite(bmp, spr, x, y, itofix(32))</code>
will rotate the graphic by 45 degrees.
<p><br>
<div class="al-api"><b><a name="I_can_t_get_the_d_bitmap_proc___or_d_icon_proc___GUI_object_to_work_"> I can't get the d_bitmap_proc() or d_icon_proc() GUI object to work!</a></b></div><br>
<p>
You are probably trying to initialise the dialog structure with a
pointer to your bitmap, right? That won't work because the dialog is
created at compile time, but the bitmap is only loaded at runtime, so
the compiler doesn't yet know where it will be located. You need to
fill in the dialog structure with a <code>NULL</code> pointer, and then copy the
real bitmap pointer into the <code>dp</code> field as part of your program init
code, after you've loaded the bitmap into memory.
<p><br>
<div class="al-api"><b><a name="Should_I_use_regular_bitmaps__RLE_sprites__or_compiled_sprites_"> Should I use regular bitmaps, RLE sprites, or compiled sprites?</a></b></div><br>
<p>
It depends on exactly what you are doing. If your images are totally
opaque, there is no advantage to using an RLE sprite, and it will
probably be faster to use a regular bitmap with the <code>blit()</code> function.
If your graphics contain masked areas, an RLE sprite may be both smaller
and faster than the <code>draw_sprite()</code> function, depending on your CPU
and your bitmaps.
Compiled sprites are in general quite a bit faster than both the
others for masked images, and slightly faster for opaque graphics, but
this is far more variable. They are at their best with small sprites,
on older machines and in mode-X, and may actually be slower than
<code>blit()</code> when using SVGA modes on a pentium (the large size of a
compiled sprite is very bad for the cache performance).
<p><br>
<div class="al-api"><b><a name="How_can_I_make_my_game_run_at_the_same_speed_on_any_computer_"> How can I make my game run at the same speed on any computer?</a></b></div><br>
<p>
You need to make sure the game logic gets updated at a regular rate,
but skip the screen refresh every now and then if the computer is too
slow to keep up. This can be done by installing a timer handler that
will increment a global variable at your game logic speed, eg:
<blockquote class="code"><pre>
volatile int speed_counter = 0;
void increment_speed_counter()
{
speed_counter++;
}
END_OF_FUNCTION(increment_speed_counter)
void play_the_game()
{
LOCK_VARIABLE(speed_counter);
LOCK_FUNCTION(increment_speed_counter);
install_int_ex(increment_speed_counter, BPS_TO_TIMER(60));
while (!game_over) {
while (speed_counter > 0) {
update_game_logic();
speed_counter--;
}
update_display();
}
}</pre></blockquote>
<p><br>
<div class="al-api"><b><a name="How_can_I_take_a_screenshot_of_my_Allegro_program_"> How can I take a screenshot of my Allegro program?</a></b></div><br>
<p>
Add a call to <code>save_bitmap()</code> somewhere in your code. See the
<code>save_bitmap()</code> documentation for a discussion of one common pitfall
when doing this, and some example code.
<p><br>
<div class="al-api"><b><a name="How_can_I_generate_a_random_number_"> How can I generate a random number?</a></b></div><br>
<p>
Call <code>srand(time(NULL))</code> at the beginning of your program, and then use
<code>rand()%limit</code> to obtain a pseudo-random number between <code>0</code> and <code>limit-1</code>.
<p><br>
<div class="al-api"><b><a name="Why_not_make_a__lite__version_of_Allegro_"> Why not make a "lite" version of Allegro?</a>
I don't need any of the sound, maths, or GUI routines...</b></div><br>
<p>
There is no need. The linker will only include the parts of the
library that you actually use, so if you don't call any of, say, the
texture mapping or FLIC playing functions, they will be left out of
your executable. This doesn't work perfectly because a lot of the
Allegro code uses tables of function pointers that cause some
unnecessary routines to be linked in, so the majority of the graphics
functions will be included in every executable, but I have tried to
keep this to a minimum. See <tt><a href="allegro.html">allegro.txt</a></tt> for information about more
precise ways to remove some of the graphics and sound drivers.
<p><br>
<div class="al-api"><b><a name="Will_you_ever_add_support_for_3D_accelerator_hardware_"> Will you ever add support for 3D accelerator hardware?</a></b></div><br>
<p>
No. This sort of hardware support would be most useful as part of a
proper 3D API, which Allegro is not, and will never be. If you want
to do some work on this, the MESA library (a free implementation
of OpenGL) is IMHO the place to start.
<p>
<p>
However, if you are interested in using OpenGL for graphics and Allegro
for everything else, you can try the various add-ons libraries linked
from <a href="http://www.allegro.cc/">http://www.allegro.cc/</a> such as AllegroGL.
<p><br>
<div class="al-api"><b><a name="Why_not_add_a_MOD_playing_function_"> Why not add a MOD playing function?</a></b></div><br>
<p>
Several very good ones already exist, for instance the JGMOD or DUMB
packages. See the audio library extensions section on the Allegro.cc
website (<a href="http://www.allegro.cc/">http://www.allegro.cc/</a>). You are not allowed to suggest
that one of these libraries be merged into Allegro, because this topic
has already been done to death on the mailing list and we are tired of it.
<p><br>
<div class="al-api"><b><a name="Why_not_add_networking_support_"> Why not add networking support?</a></b></div><br>
<p>
There are several networking packages currently in development or
floating around on the net, though, and in our opinion this sort of
code is more useful as an external library than it would be as part of
Allegro.
<p><br>
<div class="al-api"><b><a name="Why_can_t_Allegro_read_GIF_files_"> Why can't Allegro read GIF files?</a></b></div><br>
<p>
Unisys has a patent on the LZW compression algorithm that is used by
the GIF format. We want everything in Allegro to be freely usable
without any restrictions whatsoever, which means we can't include any
code that is subject to licensing or the payment of royalties.
<p><br>
<div class="al-api"><b><a name="My_program_crashes_all_the_time__Could_this_be_a_bug_in_Allegro_"> My program crashes all the time. Could this be a bug in Allegro?</a></b></div><br>
<p>
Perhaps. Try to isolate the smallest fragment of code that is able to
reproduce the problem, and we'll have a look at it. If you can send us
a 10 line program, we will fix it. 100 lines, and we can probably fix
it. 1000 lines, and we don't have a chance :-)
<p><br>
<div class="al-api"><b><a name="Can_I_use_Allegro_in_my__ltwhatever_gt_commercial_application_"> Can I use Allegro in my <whatever> commercial application?</a></b></div><br>
<p>
Sure. See the giftware terms in <tt><a href="readme.html">readme.txt</a></tt>. We don't mind what you do
with it, and there are no problems with commercial usage.
<p><br>
<div class="al-api"><b><a name="When_will__ltfoobar_gt_be_finished__I_can_t_wait___"> When will <foobar> be finished? I can't wait...</a></b></div><br>
<p>
Whenever it is done! A little encouragement is always welcome, but we
don't have any completion deadlines and we're not going to make one up
for you :-) As soon as it is finished, it will be released.
<p><br>
<div class="al-api"><b><a name="Where_can_I_get_some_fonts_to_use_with_Allegro_"> Where can I get some fonts to use with Allegro?</a></b></div><br>
<p>
The grabber can import directly from GRX or BIOS format .fnt files, or
you can draw them onto a .pcx image using any paint program. See
<a href="http://www.talula.demon.co.uk/ttf2pcx/">http://www.talula.demon.co.uk/ttf2pcx/</a> for a utility that
will convert Windows TrueType fonts into this .pcx format.
<p><br>
<div class="al-api"><b><a name="Where_can_I_find_a_set_of_instrument_samples_for_the_DIGMID_driver_"> Where can I find a set of instrument samples for the DIGMID driver?</a></b></div><br>
<p>
See the Allegro homepage (<a href="http://alleg.sourceforge.net/">http://alleg.sourceforge.net/</a>)
for some links. You can use Gravis patches (.pat format), or SoundFont
2.0 (.sf2) files, but the latter must be converted into a patches.dat
file with the pat2dat utility.
<p><br>
<div class="al-api"><b><a name="How_can_I_convert_the_documentation_into_Windows_Help_format_"> How can I convert the documentation into Windows Help format?</a></b></div><br>
<p>
You need to download the makertf conversion utility
(<a href="ftp://ftp.coast.net/Coast/win3/winhelp/mkrtf104.zip">ftp://ftp.coast.net/Coast/win3/winhelp/mkrtf104.zip</a>), and the Windows
Help compiler (<a href="ftp://ftp.microsoft.com/Softlib/MSLFILES/HC505.EXE">ftp://ftp.microsoft.com/Softlib/MSLFILES/HC505.EXE</a>).
Make a temporary directory, copy the <code>allegro.txi</code> file from the
<code>allegro/docs</code> dir, and run the commands <tt>makertf --no-warn allegro.txi
-o allegro.rtf -J allegro.hpj</tt> followed by <tt>hcp allegro.hpj</tt>. The
second command will give a lot of warnings, but they can safely be
ignored.
<p><br>
<div class="al-api"><b><a name="How_can_I_print_out_the_documentation_"> How can I print out the documentation?</a></b></div><br>
<p>
The <tt>allegro.rtf</tt> file can be read directly into Microsoft Word and
printed from there, but you should right-click and update the table of
contents and index fields to fill them with the correct data first.
Alternatively you can install the TeX package and use the tex and
dvips programs to convert <tt>allegro.txi</tt> into Postscript format.
<p><br>
<div class="al-api"><b><a name="Where_can_I_find_example_source_code__add_on_packages__and_tutorials_"> Where can I find example source code, add-on packages, and tutorials?</a></b></div><br>
<p>
Check the Allegro.cc homepage, <a href="http://www.allegro.cc/">http://www.allegro.cc/</a>.
If you have anything to add to this, please post the URL!
<p><br>
<div class="al-api"><b><a name="Why_is_it_considered_good_coding_practice_to_define_PI_as_a_constant_"> Why is it considered good coding practice to define PI as a constant,</a>
rather than just using the value 3.141592 in my code?</b></div><br>
<p>
It simplifies the maintenance of your program, in case the value of PI
ever needs to be changed. Also it will make your program more portable
to other compilers that use different values of PI.
<p><br>
<div class="al-api"><b><a name="Why_doesn_t_vsync___seem_to_work_"> Why doesn't vsync() seem to work?</a></b></div><br>
<p>
A number of graphics cards have buggy or incomplete VESA
implementations, and often the <code>vsync()</code> function is not implemented. For
examples on flicker-free drawing, look at the code for the demo game,
which uses a variety of methods to draw itself.
<p><br>
<div class="al-api"><b><a name="Why_doesn_t_busy_waiting_on_the_key_array_work__For_example_"> Why doesn't busy waiting on the key array work? For example,</a>
"while (!key[KEY_ENTER]);" doesn't work.</b></div><br>
<p>
If the code works without optimisations, then it could be the
compiler's fault. You can try beating the compiler into submission,
for example:
<blockquote class="code"><pre>
while (!key[KEY_ENTER])
rest(0);</pre></blockquote>
<p>
For this case, however, it would be better to use <code>readkey()</code> instead.
Or consider upgrading or downgrading your compiler.
<p><br>
<div class="al-api"><b><a name="I_get_lots_of_errors_when_I_try_to_compile_my_C___Allegro_program_"> I get lots of errors when I try to compile my C++ Allegro program.</a></b></div><br>
<p>
You are probably declaring the use of a namespace before including
Allegro headers. For example:
<blockquote class="code"><pre>
#include <iostream>
using namespace std;
#include <allegro.h></pre></blockquote>
<p>
Move the <tt>`using'</tt> declaration after the <tt>`include'</tt> directives referring
to Allegro headers:
<blockquote class="code"><pre>
#include <iostream>
#include <allegro.h>
using namespace std;</pre></blockquote>
<p><br>
<div class="al-api"><b><a name="I_m_still_confused__Where_can_I_get_help_"> I'm still confused. Where can I get help?</a></b></div><br>
<p>
See <a href="http://alleg.sourceforge.net/maillist.html">http://alleg.sourceforge.net/maillist.html</a>.
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