接續上一篇 22. Entity Component System (1)，如果以 Go 要如何實現呢？

這邊先找到幾個開源項目，參考別人是如何實作

• EngoEngine/ecs
• andygeiss/ecs

概念

• 基本概念是會定義一個 world 管理整個系統
• world 可能包含多個 entity，然後由 world 來執行各個 system
• 因為 sysyem 是依序執行所有執行先後問題，因此需要確認邏輯上有沒有矛盾

簡單範例會是這樣

package main

import "fmt"

type EntityID int

type PositionComponent struct {
	X, Y float64
}

type RenderComponent struct {
	Texture string
}

type RenderSystem struct {
	// 
}

func (rs *RenderSystem) Update(entities map[EntityID]interface{}) {
	for entityID, component := range entities {
		if renderComponent, ok := component.(*RenderComponent); ok {
			// 渲染邏輯
			fmt.Println(entityID, renderComponent)
		}
	}
}

type World struct {
	entities map[EntityID]interface{}
}

func (em *World) CreateEntity(components ...interface{}) EntityID {
	entityID := 0 // 生成唯一值
	em.entities[EntityID(entityID)] = components
	return EntityID(entityID)
}

func (em *World) RemoveEntity(entityID EntityID) {
	delete(em.entities, entityID)
}

func (em *World) AddComponent(entityID EntityID, component interface{}) {
	em.entities[entityID] = component
}

func (em *World) GetComponent(entityID EntityID) interface{} {
	return em.entities[entityID]
}

func main() {
	world := World{entities: make(map[EntityID]interface{})}
	renderSystem := RenderSystem{}

	player := world.CreateEntity(
		&PositionComponent{X: 100, Y: 100},
		&RenderComponent{Texture: "player.png"},
	)

	enemy := world.CreateEntity(
		&PositionComponent{X: 200, Y: 200},
		&RenderComponent{Texture: "enemy.png"},
	)

	// 遊戲循環
	//for {
	renderSystem.Update(world.entities)
	//}
}

這邊再看另外一個範例：A Go Roguelike

待補