ECS — Textures and Game Objects

Question

I'm developing a game using an entity-component system, and had a question about storing, using and linking textures to entities.

I have a GraphicsSystem that is responsible for storing and registering textures. Each entity has a GraphicsComponent including a textureID, which is just an integer used to look up the stored texture in the GraphicsSystem.

This works well for textures that are only used by one entity, for example player textures. In this case, I can create new GraphicsComponents by something like:

GraphicsComponent(graphicsSystem.addTexture("Player1.png"));

graphicsSystem.addTexture() adds a texture to the graphics system and returns an integer to its position, which is then stored in the component for later use.

My problem is that this approach doesn't work for textures that are registered once and then used across multiple entities. Examples are textures for bullets and world terrain.

My temporary solution to this problem is to register the texture once, and store the texture id centrally. Whenever I need to (for example) create a new bullet, I just need to remember that the bullet is texture id of (say) 1, and then pass this to the GraphicsComponent constructor for the bullet.

Similarly for my terrains, I currently just need to remember which texture ID is for which terrain type:

World::World() :    floorTerrain(1),
                    wallTerrain(2),
                    ...

I did think about storing these IDs somewhere, for example in the GraphicsSystem itself, but my world instance doesn't have direct access to the graphics system.

Anyway, as you can probably tell I am new to ECS game design and would appreciate any pointers!

Thanks, Rich.

Answer 1

You could have a map in graphicsSystem where the key is the name of the texture file and the value is a reference to the loaded texture object.

When adding textures by calling graphicsSystem.addTexture("TextureName.png") you return the texture pointer.

In graphicsSystem.addTexture(string s) you then check if the hash contains a value with the key s and return the texture. if it doesnt contain the key, load the texture and add the key-valuepair to the map.