Update 13 Released

Weekly Update 13 is now live on Steam. Here’s a summary of the biggest changes.

Black Screen Fix

We received a number of reports from users that were experiencing an issue where the game would start up with a black screen. This was caused by the game not being able to load any of the files it needs to execute. The common elements between the reports was Windows 8 and having the game installed to a drive other than C: After a lot of back and forth, we tracked down the issue to Windows reporting the wrong case for the directory the game was installed to. Based on the exact circumstances, it appears that this issue could have affected users with other versions of Windows or with the game installed on the C: drive, although we didn’t actually see any cases like that. Either way, it should be fixed now! If you’re still experiencing any problems please let us know.

Script Component Optimisation

One of the unique things about the Future Perfect scripting architecture is that each script runs in it’s own “sandbox” environment which keeps it isolated from all of the other running scripts. We designed the system this way for a few reasons. First, it helps create strong abstraction between scripts since they can’t depend on the internal implementation details. Similarly a run-time error in one script can’t bring down any other scripts. And finally, it allows us to run multiple scripts in parallel by creating a Lua virtual machine per-CPU thread. Since the scripts can’t directly access each other, it doesn’t mater that they’re not all in the same Lua virtual machine. In order to implement this sandboxing, each script component did a fair bit of work when it was created, including making its own copies of many of the engine’s API functions. These extra copies meant when the script component was destroyed a fair bit of garbage was created. Due to the way the client handles network prediction, script components are created and destroyed a lot as the client state is restored back in time. The garbage created by each one would eventually would lead to a big hitch in the garbage collector every few frames. We optimized the sandboxing process so that almost all of the extra API copies are unnecessary. This means script components are more lightweight and the pressure on the garbage collector is significantly reduced. This image shows the time taken per frame for the last 150 frames. As you can see, the hitches (i.e. the larger bars) are less frequent and smaller. There are still a few things we need to do to eliminate them completely. The first is changing the client prediction code to not have to recreate the script components so frequently. The second is to run the garbage collector for a small amount of time each frame so that the spikes are amortized over all of the frames. Both of these changes would have made the original problem much less visible, so we wanted to tackle it first when it was easy to measure.

User Interface Refinement

Now that the editor UI layout is in a state we’re happy with, we’re starting to work on some of the rough edges that hamper usability. One small example is the Entity Panel which is used to access the individual components of an object. Mucking with the components is an “advanced” feature of the editor; players who want to do level design