Category: Artifact

Adventures in creating a Snap from an LWJGL2 based game

The old Artifact is still kicking, not too long ago I created a Snap for it. Creating the Snap felt a bit like concocting a magical snapcraft.yaml and and hoping it works out. For the first few attempts the magic never works out, and the process of figuring things out tend to be tedious at best. This was no exception. Here are some of the problems I ran into, hope it helps someone else.

Xprop missing

My first Snap attempt immediately spit out this during startup:

java.io.IOException: Cannot run program "/usr/bin/xprop": error=2, No such file or directory

This was fixed by adding these lines to my snapcraft.yaml. The layout is needed since xprop is referred to by an absolute path. See this thread for more information.

layout:
  /usr/bin/xprop:
    bind-file: $SNAP/usr/bin/xprop

parts:
  mypart:
    stage-packages:
      - x11-utils

A xrandr puzzle

Next in line was this:

Exception in thread "main" java.lang.ExceptionInInitializerError
	at org.newdawn.slick.AppGameContainer$1.run(AppGameContainer.java:39)
	at java.security.AccessController.doPrivileged(Native Method)
	at org.newdawn.slick.AppGameContainer.<clinit>(AppGameContainer.java:36)
	at game.Artifact.main(Unknown Source)
Caused by: java.lang.ArrayIndexOutOfBoundsException: 0
	at org.lwjgl.opengl.LinuxDisplay.getAvailableDisplayModes(LinuxDisplay.java:951)
	at org.lwjgl.opengl.LinuxDisplay.init(LinuxDisplay.java:738)
	at org.lwjgl.opengl.Display.<clinit>(Display.java:138)
	... 4 more

This was caused by xrandr not being installed in the snap, which LWJGL2 uses to find display stuff. This was fixed by adding the x11-server-utils package, which installs xrandr.

stage-packages:
  - x11-xserver-utils

For debugging snaps and finding packages these commands were great.

#This allows you to look at the system as seen from the snap
snap run --shell <your-snapname> 

#This will give the package that installed an executable, in this case xrandr
dpkg-query -S /bin/xrandr

I hope this helps someone else looking to get their application in a Snap.

Artifact 1.0.4 – Hello integer overflowing highscore!

Yesterday I finally finished some of my planned Artifact updates. The new version can be downloaded from here. Below is a detailed account of the changes in this version.

  • Added a game mode (rascal), where you can not lose:

    As my 4 year old daughter was playing the game I had to keep typing cheat codes to keep her alive. This made me realise that I could introduce a game mode where it is not possible to lose, and where the player has infinite resources. Once I added the rascal mode she played for quite a while, and she even figured out some smart plays all by herself.

    • Artifact
    Rascal mode allows exploration of the game in a different way. Hello integer overflowing high score!

  • Removed global score tracking:

    Global score tracking from games not played on a server will always be prone to modified clients posting fake scores. This can be mitigated though obfuscation, but not really solved. My implementation was also very bad, and very hard to maintain. Maybe I’ll revisit this one day, but for now I am glad its gone.

  • Removed hash checks of local data:

    I do not care if you hack your local files so that you have insane scores. Hack the game all you want!

  • Prepare for OS X removal of some carbon audio API:

    I kept getting this message in my logs:

    WARNING: 140: This application, or a library it uses, is using the deprecated Carbon Component Manager for hosting Audio Units. Support for this will be removed in a future release. Also, this makes the host incompatible with version 3 audio units. Please transition to the API’s in AudioComponent.h

    The solution was to upgrade openal-soft by building from source, and replace the old openal.dylib that came with Slick2D with the libopenal.dylib built, which I guess uses the API Apple wants you to use.

Artifact 1.0.2.1 – Fixing OS X level 10+ crash

The obligatory level 10 death

For some reason Artifact-1.0.2 would crash on level 10+ on some OS X installations. This seems to stem from some issue with my LWJGL version, the bundled JVM and those OS X installations.

Artifact-1.0.2.1 includes a later JVM which seems to work in my tests. If you experience any issues with it please report using the address here.

Download Artifact-1.0.2.1 for Mac OS X

Artifact-1.0.2

Today I released Artifact-1.0.2 after finally getting my ass around to create a close to fully automated build script for Mac OS X (a topic for another blog post). The full changelog is listed below, but I instead recommend you go get it and try it!

mech-sec-new
New second orb graphics

Changelog:

  1. Added full screen and resolution management in game.
  2. Removed splash screen.
  3. Adjusted difficulties and added new names (Apprentice, Journeyman, Master).
  4. Added additional fire button, allowing better control using a touch-pad.
  5. Redesigned second orb with additional graphics and new behavior.

More in detail:

  1. The splash screen in Artifact was unnecessary and the only issue keeping me from removing it was having in-game window and resolution management.
  2. See above.
  3. The Normal and Hard game difficulties were hardly different in version 1.0.0, while the Not sane difficulty was extremely hard. Now the Apprentice difficulty is much easier then the old Normal, Journeyman is similar to the old Normal, while Master is slightly easier then the old Not Sane difficulty. The change was mainly done to make the initial difficulty easier for new players.
  4. On a touch-pad moving the mouse and clicking might interfere with each other, so I added an alternate fire welder button for those who might prefer that.
  5. The Second orb was very hard to predict and its mechanic felt wrong. The new version is cooler , and most of the time way easier to predict. It also has a slight comeback factor, which is nice in this cutthroat game.

Prepare your Welding Blaster; play Artifact

I made a computer game together with Nils Eriksen Meling and Sven Meling; It is named Artifact; go try it! It plays similarly to Barrack, a favourite game from my youth. In addition to the action and strategy found in Barrack, Artifact also adds an aspect of resource management.

blaster
Prepare your Welding Blaster, the Artifact is a cruel mistress

In Artifact, each of 40 levels consists of a screen filled with a variety of different orbs. These orbs must be isolated by you. Once 75% of the playing field has been isolated, the level ends. You are rewarded for playing fast, and for ending the level with a high % of the screen isolated.

crystalsOn
Electricity is key

To accomplish your task you control a dual-direction Welding Blaster that can be transformed to fire vertically or horizontally. When fired, a welding beam will slowly traverse the screen in 2 directions. Once both ends reach a wall, the playing field will be cut, isolating balls on each side of the beam. However, care must be taken not to hit the orbs, as they will create a feedback surge, damaging the Welding Blaster.

future_whole
I hate orbs

Artifact is free and will stay so, but developing and maintaining it is not free. If you enjoy Artifact, I hope you will consider a donation. However, most of all, I hope you enjoy playing it.
If you have problems with installation on the supported platforms, please send a mail to: .

Download Artifact