DEVLOG 5 - The ECS Architecture
 
Since I can now draw something on the screen, I’d say it’s time to start building the actual graphics engine. The first system I need to create for Eve is the management of game objects. There are two options: the first is to use the OOP programming paradigm and therefore manage game objects just like Unity does; the other, which is the one I chose, is to use the ECS (Entity, Component, System) architecture.
 
To understand why I chose ECS, you need to understand how this architecture works. As I mentioned, the word ECS is an acronym for Entity, Component, and System, which represent the three pillars on which this architecture is based. In short, entities represent objects, the essence of the object; that object simply exists, and they are usually represented by a simple numeric ID. Components, on the other hand, represent pure data; therefore, each entity can have its own components and therefore its own data. Systems, on the other hand, are the part of the code that executes the logic. Let’s take the rendering system as an example. This will iterate over all entities that have mesh components, and a transform will take their data and send it to the GPU for rendering.
 
This division of responsibilities ensures incredible efficiency, given how the CPU works, since the component data is stored contiguously in memory. This facilitates the work of a CPU component called the Hardware Prefetcher, which tries to predict which portion of RAM the CPU will use next, thus reducing cache misses.
 
There are many ready-to-use libraries for this architecture, such as Flecs, EnTT, and others. I chose to try and create my own so I could learn and understand more. Currently, I’m using, broadly speaking, the same approach Unity uses with their ECS architecture, which is part of their Unity DOTS ecosystem.
 
All entities in the game can be classified based on an ID called an Archtype, which identifies the type of entity being viewed based on its components. This way, you can have contiguous arrays and minimize cache misses, thus maximizing CPU efficiency.
 
I’m still working on it, but I have to say it’s extremely interesting…