This post will go into specifics about some of the coding challenges faced and will
be a bit technical just as a warning. The first big hurdle that i faced was getting
the obstacle avoidance steering behavior to work right. All the methods for implementing
it that I could find documented largely depended on having a precise point of collision
to calculate from as well as having some kind of bounding box around the object. However
the way that are collision system was set up it could only tell me which side of the
ship that I had collided with and not where. The bounding box problem I solved by
creating my own based on the current dimensions of the ship and while not precise
did the job. Then I had to solve the problem of getting a point by doing a plane to
line segment test on the side I knew I had collided with. This mostly worked out but
do to slight discrepancies between the dimensions stored in the ship class and the
actual model size occasionally makes for strange behavior. The next problem with the
avoidance algorithm did not occur till much later in the project. This was once the
island objects where added into the game and had a slightly different method of checking
collision against them. This involved a line segment to circle check and normally
would have gone fine but some where in the calculations a float over flow error was
happening. I had never seen this error occur before so it took me some research to
find out exactly what was happening. After that I was able to solve the problem by
putting in some checks to prevent the over flow as well as fixing a heap corruption
error I shall mention later but it was still annoying because it consumed a good couple
of days time.
Other then the problems with the obstacle avoidance the only other major AI problems
where mostly a result of my designing a system that I had never tried to create before.
This lead to me having to redo the code system a few times as well as having to rewrite
several functions. For example I had not planned to need a function for calculating
the average firing distance from the middle range weapons on the AI ship to the player
ship but had to add it in later when some of my other functions ended up needing this
information. Most of the changes where miner additions like this but they where unplanned
do took up time on the schedule. Fortunately I had allowed for some of this to happen
so I did not end up being too bad. The longest part of this was actually writing the
scripted decision trees themselves. This I had not anticipated and did put me a little
behind. The delay was mostly having to go back and edit an existing tree over and
over again till i achieved the type of behavior I wanted that particular AI to have.
In the end it was all still done on time but it did take a little longer then I thought
and did not leave me as much time as I would have like to try to go back and stream
line some of the old code that I had written. I guess I should have done that as I
wrote the code but at the time since I had scheduled for it I did not worry about
it.
The last major coding problem that I faced in the game had nothing to do with the
AI coding but with tracking down a heap corruption error. We had been seeing the error
pop up in out files for some time since the start of the project and several of us
had tried to fix it but nobody had had any luck at it yet. It was pretty miner at
first only causing a break point to be hit in debug mode and not having any real effect
in release. However it eventually started to have effect in other systems in the game.
At this time I was a little bit ahead of schedule so I decided to take a look at it.
I went through every line of code looking for possible places that could cause that
kind of bug. I had to do this because we had already tried more traditional bugging
techniques and was getting no where with them. After reading through the code I finally
tracked it down to a problem in out font system that was using local memory to create
some of the storage classes for the fonts. It was a very easy fix once I found it
but it was hard to find.
Well thats the hight lights of the coding challenges that I ran into a few other things
where took a lot of work to get done but still fell into the area of work that I had
expected to have to do. Other miner bugs showed up as well but nothing that took more
then a couple of hours to track down and fix.
