valhalla_ecs 0.0.2-alpha

Valhalla ECS - VECS

An Entity Component System library written in D.

Brief

An entity component system is a pattern used mostly in gamedev. The objective is to classify everything in a game as an Entity. Components are just data structures used to give so sort of meaning to the generated entities. Some common examples are: Position, Velocity, Sprite. All these components can be associated to an entity. An entity can be rendered if has Position and Sprite, etc. Components can be almost anything! A System gives functionality to entities. Some common examples are: Render, Collision, Movement.

This project aims to create an easy-to-use yet robust and fast ECS library. It's inspired by the Entt C++ lib which revolutioned the ECS model using Sparsed-Sets as storage for components and entities, Hecs Rust lib and Bevy Rust engine, (which uses hecs) for their user-friendly approach.

Code Example

import vecs;

struct Position
{
	float x = 0.0f;
	float y = 0.0f;
}

struct Velocity
{
	float x = 0.0f;
	float y = 0.0f;
}

struct Grounder {}
struct Crawler {}

// loops through all (Position, Velocity) components
void systemA(Query!(Tuple!(Position, Velocity)) query)
{
	foreach(pos, vel; query)
	{
		*pos.x += *vel.x
		*pos.y += *vel.y
	}
}

// loops through all (Position, Velocity) components and entities with (Grounder)
void systemB(Query!(Tuple!(Entity,Position,Velocity), With!Grounder) query)
{
	foreach(e, pos, vel; query)
	{
		*pos.x += *vel.x
		*pos.y += *vel.y
	}
}

// loops through all (Position, Velocity) components of entities with (Grounder) and without (Crawler)
void systemC(Query!(Tuple!(Position,Velocity), Tuple!(With!Grounder, Without!Crawler)) query)
{
	...
}

void main()
{
	auto em = new EntityManager();

	em.entityBuilder()
		.gen!Position
		.gen!(Position, Velocity, Grounder)
		.gen(Position(3.0f, 6.0f))
		.gen(Velocity(2.0f, 1.0f), Position(3.0f, 6.0f), Grounder.init, Crawler.init);

	systemA(em.query!(Tuple!(Position,Velocity)));
	systemB(em.query!(Tuple!(Entity, Position,Velocity), With!Grounder));
	systemC(em.query!(Tuple!(Position,Velocity), Tuple!(With!Grounder, Without!Crawler)));
}

Almost anything can be a component

import vecs;

struct Foo {}

void main()
{
	auto em = new EntityManager();

	em.gen(1, 43f, Foo.init);
	em.gen(1, true, "entity");
	em.gen(false, Foo.init, 123);
}

Future features:

• Groups (similar to Entt)
• Further optimize Query
• Full nogc support
• Optimize entity generation
• System support within EntityManager (similar to Bevy/Hecs)
• Events/Signals
• Fast access to some Storage methods with Query (like remove)

License:

Licensed under:

• MIT license

Contribution:

If you are interested in project and want to improve it, creating issues and pull requests are highly appretiated!