Exporting...
On Thursday I managed to get the Export of the Levels to work. This involves exporting the Assets ( Meshes, Textures, Sounds ) and the Entities( Components, Data Components ). After doing this the only thing I had left to do is allow editing of the rotation of the entities, which posed a problem. Up until now I had been directly editing the Matrix of the Mesh Instance I had selected. This was fine except to do rotation I would need to store the Euler Angles that could be edited from the User Interface.
This got me thinking, I should be using the Entity Component System(ECS) for all of this data realistically, and I will also be wanting to edit values of the Data Components from within the Level Editor as this will make entity creation much better. In my current system for ECS there isn't any way of getting a Data Component for an Entity without doing a dynamic cast based on some sort of ID which could potentially go wrong. So I started looking at different solutions for ECS since my first initial implementation. I came across this post: ECS, Component, Entities and Systems, which suggests the use of the Curiously Recurring Template Pattern(CRTP) for the ECS.
First Attempt
Most of Thursday night was spent refactoring my current ECS from a virtual inheritance style hierarchy to this CRTP version. Needless to say after a lot of Linking Errors and all sorts of crazy going on I decided to scrap it and revert my changes.
Second Attempt
So for my second attempt I decided to create a seperate project for my ECS and get it all set up with the templates before integrating it into the engine. I am part way through this, I've got all the Components and Data Components working I just haven't dealt with the messaging yet. I have really mixed things up, instead of storing Components within the entity I have created pools of all the same types and they just have reference to their entity. This way has a few benefits such as cache coherency, the updates will also be Component Priority dependant rather than Entity Creation dependant. This approach will also give me better opportunity to perform multi-threading when the time comes, each pool could use worker threads to update chunks of the Components.
One thing I am likely to change is the wording I previously used, in most descriptions of an ECS the words System and Component are used where as mine uses Component and Data Component which really confuses things as:
Comp = Component
System = Component
Okay so finally a demo of what access to the new Components will look like:
auto posComponent = entity->GetComponent();also as I have used Variadic templates so the adding of Components to entities is clean and simple:
entity->AddComponent( x, y, z );Okay so there is still a lot of work to be done but I'm hoping to get this all nailed pretty soon so I can really start using the ECS.
Cheers :)
