In my relentless pursuit of increasing software development productivity, I started the week off pondering what is slowing me down the most. I kept coming back to aspects of object-oriented programming – encapsulation, abstraction, inheritance/composition, polymorphism. OOP has always been a double-edged sword for me, providing both solutions and problems. Certainly some of my issues are the result of my shortcomings as a developer, but I believe there are inherent shortcomings in OOP as well. A frequent challenge is determining where things belong, and a frequent source of bugs is putting things in the wrong place. I began questioning whether data and functionality belonged together in the same class (I was quite deep into the rabbit hole at this point) and if I could reduce complexity by separating the two. I also considered making data and functionality, once separated, completely public (I know, OOP heresy) and using either immutable or versioned data. I googled these ideas to see what already existed and found something very close: Data-Oriented Programming (DOP). Now, it would be impractical to go back and rewrite 2+ years of code using a DOP paradigm. But, I’m going to experiment with it for some of the new code I’m writing (see the AI example below).
- AI Overhaul part 2. I thought I was done with AI rework after last week, but I put even more time into it this week. To make the new composition-based AI configurable in the Unity editor, I added AIType classes (implementing the Type Object pattern). inheriting from ScriptableObject, I also made the pluggable components of AIType, such as the observation and action deciders, ScriptableObjects. The legacy AI classes were gutted and consolidated. AI state data was moved into a separate generic data structure (see below) and AI functionality was moved into the AIType classes. I added general AI behaviors such as offense and flee, and mapped actions to the behaviors. This simplifies the action decider code because only the behavior has to be specified; the behavior class will return all of the applicable actions to the action decider. With these improvements, I can assemble AI’s in the Unity editor, provided that the pluggable components have been written. I may need to move to data-driven behavior trees if the AI logic becomes too complicated, but for now I’ll stick with conditional statements.
- Generic Data Structure. To support my data-oriented programming experiment, I created a class to act as a general-purpose data container. It’s essentially a map data structure, but contains three dictionaries to store values of different types (bools, ints, and objects). It’s not sophisticated but it works. I’m now using this to store AI state data, which varies by AI type. The syntax for accessing data within the structure is more cumbersome than individually defined variables, but that drawback is outweighed by flexibility and ease of serialization/deserialization. I also like that the syntax makes it obvious which variables are part of the state.
Next week’s goals are the same as last week’s goals: add the vampire and 1-2 more enemies to test the new AI, and add a few new abilities.