JevaEngine Update - July 24th, 2014

JevaEngine has been dormant for the last couple of months. The repository has also seemed pretty inactive.

Here is a sample of the current demo modules of JevaEngine and the world editor. They look the same (and admittedly could use some polishing) but they come after some major refactors on the engine. More details below the video.

I have been refactoring JevaEngine over the last month or so. These refactors come with some very important architectural changes that pushes JevaEngine towards a more flexible and powerful engine. I will be detailing the changes within the next few weeks once the refactored engine has been pushed to the repository. Below I will list some of the key changes to JevaEngine.

- All use of service locator pattern has been refactored out of the engine. The service locator pattern was used in JevaEngine to acquire an interface to the concrete implementation of Game, and to acquire an interface to the globally accessible asset factory (opening raw InputStreams to the game's filesystem.) This provided a convenient way for one to construct entities, open configuration files from anywhere inside of JevaEngine. However it also carried some issues, mainly allowing for global access to these resources (forcing factories to be thread safe) and hiding code smells that would usually become obvious.

- JevaEngine has now switched to an entirely Dependency Injection based model of passing around dependencies, using Guice to bootstrap the engine with the appropriate dependencies. This has allowed for more flexibility inside of JevaEngine. Including the ability to bootstrap JevaEngine with custom world, sprite, script, entity, physics and asset factories - allowing one to easily integrate custom file formats and scripting/physics engine seamlessly into JevaEngine.

- World projection has been entirely decoupled from the engine. Meaning one can implement various render perspectives into JevaEngine seamlessly. JevaEngine is no longer focused specifically towards Isometric Games, it can also focus towards platformers and top-down games. While no such implementations have been tested, it is theoretically possible to easily integrate these perspectives into JevaEngine.

- The world builder has been entirely reconstructed. The previous implementation was falling apart - mainly due to complications introduced by using the Swing UI subsystem so heavily. JevaEngine's new world builder is entirely based around the JevaEngine UI subsystem. This allows for a much more functional and cleaner implementation.

- JevaEngine now delegates Window construction to an injected Window Factory. The default Window Factory parses an external configuration file that defines the layout of the window and its style. The layout defines controls, their location and their respective properties (such as text, or width/height etc...) The constructed window is than injected with a behavior. This makes the task such as localization much more achievable. It also reduces the noise in UI relevant code by allowing the programmer to focus specifically on the behavior of the window rather than its layout.

- JevaEngine is now fully integrated with a physics engine (the default implementation is pure java Box2D, but it is very easy to bootstrap JevaEngine with a different physics engine.) Following this integration, JevaEngine now comes with some steering behaviors.

- These refactors have had a significant impact on the engine, and will also require some significant refactors to be applied to the client\server implementations. For the next few weeks, I will be focusing specifically on the rpgbase and the single player demos. The multiplayer implementation is being placed on the back burner for a few more weeks.

- JevaEngine now makes the appropriate use of checked and unchecked exceptions. This has made JevaEngine respond much more appropriately to errors. Developing with JevaEngine has become significantly easier. JevaEngine uses SLF4J to report errors (such as those that exist in entity scripts.) In the previous revisions of JevaEngine, when an error was encountered (such as one in an Entity's behavior script) an unchecked exception was thrown and eventually crashed the entire engine with an appropriate stack-trace. This is unacceptable and makes the job of a casual user of JevaEngine significantly more difficult. In the latest revision (in a scenario such as this) JevaEngine now logs the error in the script to the appropriate logger, and reverts to default behavior (such as that for an entity absent of a script.)

I now work full time (unfortunately) and have to work very hard to progress anywhere with JevaEngine. That said, I am very satisfied with the results of my work over the past few weeks.

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