goecs

README

goecs

A simple Go ECS

Info

Entity–component–system (ECS) is an architectural patter that follows the composition over inheritance principle that allows greater flexibility in defining entities where every object in a world.

Every entity consists of one or more components which contains data or state. Therefore, the behavior of an entity can be changed at runtime by systems that add, remove or mutate components.

This eliminates the ambiguity problems of deep and wide inheritance hierarchies that are difficult to understand, maintain and extend.

Common ECS approaches are highly compatible and often combined with data-oriented design techniques.

For a more in deep read on this topic I could recommend this article.

Example

Run it on the Go Playground

package main

import (
	"fmt"
	"github.com/juan-medina/goecs/pkg/entity"
	"github.com/juan-medina/goecs/pkg/world"
	"reflect"
)

// Simple Usage
func main() {
	// creates the world
	wld := world.New()

	// ad our movement system
	wld.AddSystem(MovementSystem)

	// add a first entity
	wld.Add(entity.New(
		Pos{X: 0, Y: 0},
		Vel{X: 1, Y: 1},
	))

	// this entity shouldn't be updated
	wld.Add(entity.New(
		Pos{X: 2, Y: 2},
	))

	// add a third entity
	wld.Add(entity.New(
		Pos{X: 2, Y: 2},
		Vel{X: 3, Y: 3},
	))

	// ask the world to update
	_ = wld.Update(0.5)

	// print the world
	fmt.Printf("world: %v", wld)
}

// MovementSystem is a simple movement system
func MovementSystem(wld *world.World, delta float32) error {
	for it := wld.Iterator(PosType, VelType); it != nil; it = it.Next() {
		ent := it.Value()
		pos := ent.Get(PosType).(Pos)
		vel := ent.Get(VelType).(Vel)

		pos.X += vel.X * delta
		pos.Y += vel.Y * delta

		ent.Set(pos)
	}

	return nil
}

// Pos represent a 2D position
type Pos struct {
	X float32
	Y float32
}

// PosType is the reflect.Type of Pos
var PosType = reflect.TypeOf(Pos{})

// Vel represent a 2D velocity
type Vel struct {
	X float32
	Y float32
}

// VelType is the reflect.Type of Vel
var VelType = reflect.TypeOf(Vel{})

This will output:

world: World{view: View{entities: [Entity{id{0},main.Pos{0.5 0.5},main.Vel{1 1}},Entity{id{1},main.Pos{2 2}},Entity{id{2},main.Pos{3.5 3.5},main.Vel{3 3}}]}, systems: [{main.MovementSystem}] listeners: []}

Installation

go get -v -u github.com/juan-medina/goecs

License

    Copyright (C) 2020 Juan Medina

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.