I started working on loading better models, so we could start visually equipping armor and weapons when they are equipped in the inventory. Turns out, blender has a different up axis from OpenGL, so we ended up with… well this.

I got frustrated trying to get the models exporting to a proper format with the required transforms applied so that they show up in game, so I switched to something easier and more relaxing. Writing a compiler.

I started working on scripting for the dialog system, but ran into some limitations with the existing languages. I needed to be able to call Java methods to set up chat windows, then display the window and wait indefinitely for the user to make a choice. Then we would resume with the script and jump to a location based on the results.

Unfortunately, it seems like Lua does not support what we need, so I started designing my own language. I wrote a grammar based on Java syntax with a couple rules.

1. Scripts are a single file, with no classes or methods, and there is exactly one script per file
2. No memory allocation (new, array initialization, etc) will be done in the script, but you’re free to interact with memory created by Java
3. We need labels and goto’s to support the types of dialogs we want to have, on top of normal control flow like conditionals and loops

Next, I used ANTLR 4 to generate a lexer and parser, which is used to generate a parse tree. Then I wrote some code that transforms the parse tree to an abstract syntax tree. I started working on validations for the tree (like type checking), and optimizations (like pre-computing constant expressions) using a visitor pattern to traverse the tree.

I also started working on a runtime interpreter for the code, and the instructions that will execute on the interpreter. The featured image shows a console that I am building to be able to see the syntax tree, types, and runtime state of the interpreter to test the system.

Next I need to finish up the instruction generation and interpreter. There may be some fun with reflection to allow field/array access and method calls on objects, since type erasure will probably get in our way. Finally once everything is working, I need to start registering Java methods with the runtime so we can start using the scripts to build dialogs.

I should also start cleaning up the dialog UI because it currently looks like this:

One more note, I started moving windows and scene controls to a toolbar at the top of the window and added a button to shut the game down. You can see the windows dropdown open in the screenshot.