=== prerequisites ===

- a POSIX compliant OS and libc (for example linux with musl libc).
  if you're still using winblows, bad luck, you should strongly consider to
  switch to linux NOW rather than later.
- a working C99 compiler
- perl (needed for the build system)
- SDL and SDL_audio library and headers.
  this means you need the -dev(el) version of the package for your distro.

there's an alternate audio backend using libao, which has a much nicer API
than SDL_audio, however it seems to trigger some in-kernel ALSA bugs
which will lead to high CPU consumption depending on the second the game
was started (i.e. if you start the game at second X, it may consume 10%,
if you start it at second Y, it may consume 70%).

=== build instructions ===

mkdir /tmp/openDOW-000
cd /tmp/openDOW-000/
git clone https://github.com/rofl0r/openDOW
git clone https://github.com/rofl0r/libulz lib
git clone https://github.com/rofl0r/c-flod
git clone https://github.com/rofl0r/rcb2
ln -s rcb2.py rcb2/rcb2
cd openDOW/
echo "CFLAGS+=-DAUDIO_BACKEND=AUDIO_BACKEND_SDL" > config.mak
PATH="/tmp/openDOW-000/rcb:$PATH" make

=== supported compilers ===

GCC
clang

=== how to play ===

run ./spriteview.out (main game executable will be renamed at
some point)

use wasd to move the player, and the mouse to aim and fire.
switch weapons with numpad +/-.
at some point it is planned to make the layout configurable
and add support for the original behaviour without mouse aiming
so it could be used via a joystick.

== current state and TODO ==

at current, all maps are finished as far as the background
and foreground tiles are concerned, as well as all of the game
mechanics (besides dying).

the biggest part of the work is to recreate the spawn positions
and routes taken by enemy soldiers. there's roughly 500 of 'em
per map.
at current, only australias "spawnmap" is implemented. the other
maps are partially playable, but they use australias spawnmap.
that means enemies will spawn in places they're not supposed to
be, like on top of a wall, and move through the wall.

spawnmaps can be created by moving the player through the screen
step-by-step, carefully comparing to the original in an emulator.

when you are on the same "spawn line", you can press "e" to enter
the spawn editor and summon an enemy.
- use shift+numpad+/- to change its shape;
- use "d" to change its direction then, enter one of
  w,o,s,n,nw,no,sw,so,nnw,wnw,nno,ono,ssw,wsw,sso,oso
  (o means "ost", the german equivalent to "east").
- use + and - on the numeric keypad to change the velocity of the
  enemy. (it will start running around, once offscreen, it will
  respawn in the start position)
- use "g" to change its weapon type to grenade or back to gun
- press "s" to shoot at the current position
- press "p" to stop the enemy at the current position
- press crtl+numpad+ to insert a direction/speed change,
  "i" to insert the current position,
  then enter the new direction using "d".
- press alt+numpad+ to enter a new shoot "slot", and "s" to save
  the current position as the position to shoot.

if something is unclear, you should look at the implementation
of enemytag.c.

the editor takes a bit getting used to, but once you used it for
a while it's pretty quick.
after the enemy takes the same route and shots as the original,
press "e" again to exit the editor. that will output a C struct
to stdout, which you can copy paste into a spawnmap .c file
based on maps/spawn_australia.c.

=== contributing ===

if you're a C++ programmer, go away now.
if you're using MSVC, go away now.

OpenDOW uses C99, and C99 only.

i will not ever make any compromise just to make it compile on the
crippled M$ compiler.

there's not really much to help in terms of code anyway.
almost anything is done. what really needs help is adding spawnmaps
for the ~500 enemies per map.

i will only accept code contributions with small, nice and clean commits,
where every commits just does a single thing.
there's no chance i will ever merge a huge diff touching 500 lines
in several different compilation units.

i also will not add ifdef hells just to make the code compile on
crippled platform X.

so if you still want to contribute, clone the repo on github,
create a new branch for your changes, commit your work and then file
a pull request. please use commit messages that make sense and serve
as a good documentation for your changes.