Devlog #16 Sprite Batching

Perhaps the most important critique in game development is performance. The features that I have added to my project so far inevitably reflect negatively on the game performance. Because At this stage, of course, I have to implement to more efficient ways. Basically, if you try to expand the game, you have to call more draw methods. For example, I had to call too many draw methods while adding the semi-dynamic lighting to the project. Well, my prototype didn't slow down much, but in case I use a bigger map, that's going to be problem for me. Fortunately, I learned that it is a technique that I can easily apply to my entire project. This is a system called sprite batching.

So what is this sprite batching? In short, calling multiple game objects a single draw method. For instance, that is calling 10 draw methods or 1 draw method instead of calling 100 draw methods for 100 objects. This system is a well known and used system. I have never used it until now.

Before I started typing this devlog, I had to type this system myself in a small project. I will add some benchmarks. I will evaluate the CPU, GPU, and RAM usage side of the benchmark through Task Manager. In addition, I will already get the FPS values through the program.

Firsly, I will draw each of 32px square sprites on the screen one by one. So I'm going to draw 100000 objects on the screen. In this case I have to call 100000 draw methods. 

According to the values that I got:

• CPU usage(max.): 14.9%
• GPU usage(max.): 30.5%
• RAM usage: 102.1MB
• FPS: 4

I will draw 102000 objects on the screen by batching sprites, and using only one draw method:

• CPU usage(max.): 7.2%
• GPU usage(max.): 60%
• RAM usage: 89MB
• FPS(max. - theoric): 359

Frankly, the sprite batcing system made a big difference. Obviously, there is a serious GPU usage increase. It may be due to the fact that I do not use sprite batching system properly. It may not be a good idea to send a lot of data at once with just one call. I will not make a game with several hundred thousand objects. So this will be a really small but nice and efficient improvement for my prototype.