Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time
  GTK Cervi, What is it?

 GTK Cervi is clone of Cervi.  I'm not really sure if Cervi is original name
 of it but I know this game as Cervi so it will be named GTK Cervi.  It is
 a multiplayer game (for 2-8 players) where players drive their worms.  Worms
 are getting longer and players mustn't collide with any worm.  Winner is the
 last surviving worm.  For more information see `Gameplay internals' section.

  Differences (additions) to Cervi

 Here is a list of actual known differences and additions to Cervi's look
 and/or gameplay:

 * Some little differences in gameplay - these won't be fixed because I like
   this gameplay.
 * Our cerv's are antialiased.
 * We have different field size, and it can be changed.
 * Different controls.
 * More players.
 * Different scoring.
 * Hatrick and extra hatrick bonuses.


 Controls for 7th - 8th player aren't yet defined and there is no way to set
 them without altering source code ( line 45).  We will try to define
 them so game will be playable in good number of players on desktop and on
 notebook (on most notebooks you can connect 2nd keyboard and then it will
 be very playable).  Here is a list of controls for 1st - 6th player:

     Turn left | Turn right
 1.        'N' | 'M'
 2.    '!' '1' | '2' '@'
 3.    '[' '{' | '}' ']'
 4.        'S' | 'D'
 5.   numpad 1 | numpad 2
 6.   numpad + | numpad -

  Compiling and installing

 You will need these:
  * GNU C++ compiler (gcc & g++) (I don't know version, maybe 2.9 at least)
  * GNU C library (glibc) (I don't know version, 2.2.5 at least recommended)
  * GNU Standard C++ library (libstdc++) v2 (v3 is better of course) (that one
    shipped with your GNU C++ compiler)
  * GIMP Toolkit (GTK+) and GIMP Drawing Kit (I don't know version, maybe 1.2
    at least)
  * ESound (I don't know version)
  * Timidity (I don't know version)

 If you want to compile it, install it and use it, do:
  $ su -
  # make install
  or (if you want to build as non-privileged user and install as root)
  $ make
  $ su -
  # make install
  (they are the same)

  (yes, there is NO configure script, ask me why)

 If you want to compile it faster (for developing, where you needn't
 optimalisation), do:
  $ make

 If you want to compile with debugging symbols, do:
  $ make DEBUG		# (or make DEBUG=yes)
 or change the line `DEBUG=no' in Makefile.

 If you want to change install paths and/or some other things, they are at
 beggining of Makefile.

 If there are any compiling and/or installing problems, write to and post your make output, your `uname -mrspv`, version of
 needed things (as listed above) and your distribution name (for Linux, etc.).
 Maybe I won't be able to tell you simple solution for that problem so please
 try to fix it by hand and post me what to do.


 If you want to help me with development...
  ...actively, you have to mail me to, and keep my coding
     style please.
  ...passively, you have to send comments and/or patches to, and you do not need to keep my coding style if you
     have some reason for it because I will go through your patches and fix it
     to fit my likes.

  Gameplay internals

 If you want to know exact rules for GTK Cervi, read this and for more details
 look in sources (mainly  Also if you want to program your own Cervi
 clone and you don't know some things or you have some problems which you
 cannot solve, look here.

 At first, I will describe starting positions.  You can choose between `Look
 at center' and `Look from center':

 `Look at center':
  This placing is taken from original Cervi and slightly modified.  We choose
  random angle in range <0; 2*M_PI).  This must differ from any other at least
  0.4 (M_PI / 8).  Then we choose random radius, so cerv will start in the
  second 1/3 in distance from edge to center.  Then we compute x and y
  position of cerv, so they start going towards center.  Distance between any
  two cerv's must be longer than 50.

 `Look from center':
  All cerv's are placed directly to the center.  Their angles are set
  regularly with some variation so they will look like a star.  Then we move
  them a little forward, so there will be a little circle left (in the middle
  of field).  How far they are moved is computed from a number of cerv's so
  there are similar distances between them.

 At next, I will describe how speed works and what speed we choose at
 beginning.  Speed specifies, how many units (pixels, but precision is much
 better) we travel in one second.  Rotation speed specifies a radius (not
 absolute) of the smallest circle which can cerv draw.  Rotation speed 150
 specifies, that we add speed to angle in one second.  Average speed is 100
 and average rotation speed is 10 (rotation speed isn't random).  Starting
 speed is a random number in range <70; 120).  But real starting speed is
 1 and it will grow to that speed in one second.

 What happens then?  Every 10 (at least) milliseconds we update cerv's and
 display.  Cerv updating is done for each millisecond (so 8 player game will
 do 8000 updates per second, which is many (many FP ops - sins, cosins, etc.)
 and it still eats only 0.5% CPU on Celeron 233).  And what happens in cerv
 updating?  We update position (each millisecond) and if it (rounded) changes,
 we do collision checking, set bits in bitfield (for collision checking) and
 we draw a little circle there.

 You can ask why update every millisecond.  Because we don't exactly know how
 often we should update to have nice lines.  But surely not less than one
 millisecond and surely less than 10 milliseconds.  There was one bug.  We
 checked for collisions after cycle of updates (each with 1 millisecond tick)
 and sometimes cerv went through another.  I solved it this way - collision
 checking was done for every update - every 1 millisecond.  But what I got was
 another, hard to find, bug.  I will explain it after collision checking

 Now (after fixing that bug) we check for collision only when rounded position
 changes.  Checking is easy.  In bitfield, cerv's are drawn as in fig.1.  Then
 we check three pixels as in fig.2. Of course not always these three pixels
 but always the three pixels which are in the same 1/4 of full angle as cerv's
 angle.  So three pixels in fig.2 are checked for example for angle M_PI_4
 (= 45 degrees) (0 is to the right).  Of course cerv collides also on edges.

 +---+---+---+---+---+    +---+---+---+---+---+    +---+---+---+---+---+
 |   |   |   |   |   |    |   |   |   |   |   |    |   |   |   |   |   |
 +---+---+---+---+---+    +---+---+---+---+---+    +---+---+---+---+---+
 |   |   |###|   |   |    |   |   |###|   |   |    |   |   |###|   |   |
 +---+---+---+---+---+    +---+---+---+---+---+    +---+---+---+---+---+
 |   |###|###|###|   |    |   |###|###|###|???|    | ? |###|###|###|###|
 +---+---+---+---+---+    +---+---+---+---+---+    +---+---+---+---+---+
 |   |   |###|   |   |    |   |   |###|???|   |    |   |#?#|###|###|###|
 +---+---+---+---+---+    +---+---+---+---+---+    +---+---+---+---+---+
 |   |   |   |   |   |    |   |   |???|   |   |    |   |   |#?#|###|###|
 +---+---+---+---+---+    +---+---+---+---+---+    +---+---+---+---+---+
         fig.1                    fig.2                    fig.3

 Now you know how checking works so I can explain that strange bug.  We played
 and sometimes one of us collided, but we did'n see where.  He simply stopped
 in free place.  No other cerv or edge where to collide.  After some time
 I found where I did a mistake.  Imagine a situation as in fig.3, you are at
 center of the figure and your angle is a little more than M_PI (between 180
 and 181 degrees).  Now you start turning left and your angle goes under M_PI.
 But your rounded position hasn't yet changed.  So now we check those three
 pixels marked with ?.  And this causes collision.  If we check only when our
 rounded position changes, this cannot happen.  We do so.

 But there are yet some things that are done during update.  If someone
 collides, others speeds are increased by 20.  We alse set place numbers for
 collided cerv's, so we can then figure out who is winner etc.  We check if
 round is over then.  And if only one cerv left, we collide him to end round.

 So we know who won round, who was second etc.  We use a very simple scoring,
 no points for three places, nothing difficult.  For a win, you get 1 point.
 Simple.  But you can win, win and still win and nobody would say that you're
 still winning.  So for three wins in a line you get HATRICK.  With HATRICK
 you get additional 3 points. And if you win 7 times more (10 times at all),
 you get EXTRA HATRICK and 10 point bonus.  These bonuses are written with big
 bold font in the middle of field with your color so everybody knows that you
 just got HATRICK.  Only for having a complete description for this, after you
 got HATRICK, you have 6 points in 3 rounds (+3p) and after getting EXTRA
 HATRICK you have 23 points in 10 rounds (+3p +10p).  If you're still winning,
 nothing will happen.  So if you want more points, it is good to lose one
 round and then get EXTRA HATRICK and repeat it over and over.

 == Written by Tomas Janousek, (C) 2003

vim:set tw=78 ai fo=t1:


GTK Cervi







No releases published


No packages published