Wednesday, 22 October 2014

Phase 3: Snake

Feeling somewhat dejected at my inability to move forward, I decided to give the Engine a test run by making a simple game: Snake. I had a bit of time off work, so I thought it could be something I’d do in a day or two and then build from there. To get it fully working ended up taking much longer, though that was partly because I spent my holidays having an actual break.

What it did teach me, however, was precisely what was easy and what was difficult to do with the Engine as it stood. One development constraint I imposed on myself, which ultimately made it take longer, was I tried to do the Snake game code as wholly separate from the rest of my engine code. So my Play Game State acted as a bridge between the Engine and a separate SnakeGame class that did the equivalent thing – complete with having to mess around with how input is processed.

One thing the process immediately confirmed for me was how inadequate the RenderObject objects were for any sort of game code. In the TextureObject, I had code for pulling out individual frames. In RenderObject, I had code for sorting out source and destination rects for rendering. Between them, both did enough for basic rendering purposes, but it was a pain to do things like change which frame of an animation block to point to. So in order to have my snake change from a head to a body part, and a body part to a tail, was to keep reference to both the snake texture and the render object for the part and do the frame shift in the code.

The reason the objects were the way they were is they served purposes for the function. I wanted an object that could encapsulate an SDL texture while also encapsulating how to break the image down into frames. I achieved what I wanted with the TextureObject, just as I achieved what I wanted with RenderObject, which was an object that could be thrown en masse at the Render class to blindly put onto the screen.

The TextureObject / RenderObject functionality was one of the concerns I had with The Grand Design approach I took earlier. Since SDL does a lot of the core functionality for me, what I'm doing is translating between those core SDL structures and my own Game structures. But because I’m working with the SDL structures as endpoints, I was never sure what value my own wrappers were adding. Furthermore, I was not sure how the wrappers would work in a game. Building Snake gave me a valuable insight into my initial design choices.

It was nice that after I had finally gotten Snake up and working was that I could refactor the code quite quickly. It took me an evening to replace RenderObject with AnimationObject as a game component, with AnimationObject doing what I had to do manually in each game object class when it came to rendering. It took me another evening to expand on AnimationObject so that animation would just work without any intervention on the class. Very quickly I had built up a Run Once and a Loop animation, both of which worked with very little tweaking. Sometimes you've got to love the power of OO!

What was a pleasant surprise was just how much of The Grand Design just worked. Aside from enhancing the RenderObject / Render classes to allow for rotation (so I could point the head in the direction of movement), almost all of the code I did for Snake was in its own set of classes. There was at least some vindication of my earlier approach.

In terms of a development strategy, I find this the most useful process so far. Mainly because now I have a target by which to aim for, and each point of refactoring is an enhancement of the Engine itself. With the AnimationObject, I was able to quickly address the inadequacies of both TextureObject and RenderObject for game code – both were far too low level for any game object to need to have to deal with, and the code general code that would have been useful to ally the two objects was being written multiple times.

I think going forward; this is the way to work. Next I want to get my Level / Camera / Tile combination finished, which I skipped over in Snake by manually generating a list of “Wall” objects that got iterated through every cycle. After that, it’s getting text writing to the screen (an easily achievable enhancement to snake – keeping track of the score and high score), and then I think it'll be enough to start working on a different game prototype to enhance the engine further.

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