Interactive tabletop playing surface (Space Hulk Hobby Challenge)

For some it’s things like this. Horrible, scary, angry aliens, with big claws and acid for drool. For some of us, it’s more mundane things. Like – what the hell is going on here….

There’s a weird bug and it’s stuff like this that takes aaaaggges to track down and fix. On the face of it, everything is working well. Although I’m playing as the alien team, I’ve loaded up the last turn played and asked the computer to play it through.

As expected, I’m prompted to pick up and then put down each of the first two characters in turn – exactly replicating the movements I made when the turn was recorded.

Then something funny goes on with the last “genestealer” character. He’s decided he’s not going to hang around and wait for me to pick up and put down the miniatures, he’s off on his own.

Until the very last move. Then the app wants me to put the miniature down in its final resting place. But not on any of the squares inbetween. Yet the first two characters worked just fine.

THIS is the kind of nonsense that keeps me awake at night!

I built a sort-of scripting language for replaying turns and whenever one move (into a new square) or one action is complete, I call a function to say “are there any other moves left to do?”

This obviously works, because the third character happily carries them out without prompting. As characters are moved across the board, they constantly check “can anyone see me?”. If a piece is to be moved (or an action, such as firing) is to be carried out by a character that cannot be seen, the computer makes the on-screen avatar invisible and carries out the instruction with no intervention (it doesn’t hang around waiting for you to pick up or put down miniatures on the board, it’s basically “hidden movement”).

As any programmer/engineer will tell you, it’s the intermittent problems that are the worst. I wrote a function into which I pass a destination and a team number and ask it to return true or false to the question “can any of my team see this square?”

It turns out that when the first two genestealers get up and go, the question “can team 2 see the character moving?” is true, because of the third character who remains behind on the starting square.

The problem is, when it’s the last character’s turn to move, nobody else on that team can actually see the moving character (since they’re facing the other way and I’ve already built the field-of-vision system that stops them seeing outside of a 180 degree arc!).

So even through the character is plainly visible on the screen, the computer thinks “well, if nobody can see this guy moving around, why wait for the player to pick up and put down their miniatures, just keep going until he appears in the line-of-sight of another character on team two…..”

Of course, what the function should return is “if you’re player two and the character moving is on team two, you should always be able to see it” – not only would this fix the bug, it’d also mean avoiding having to do lots of (cpu) costly raytracing and line-of-sight calculations.

And that’s the kind of dumb logic puzzle this game has descended into. I’m less fighting against the computer and more against my own facepalm stupidity!