fireblade-ecs/Sources/FirebladeECSDemo/main.swift

import CSDL2
import FirebladeECS

if SDL_Init(SDL_INIT_VIDEO) != 0 {
	fatalError("could not init video")
}
let width: Int32 = 640
let height: Int32 = 480
let hWin = SDL_CreateWindow("Fireblade ECS demo", 100, 100, width, height, SDL_WINDOW_SHOWN.rawValue)
if hWin == nil {
	SDL_Quit()
	fatalError("could not crate window")
}

func randNorm() -> Double {
	return Double(arc4random()) / Double(UInt32.max)
}

// won't produce pure black
func randColor() -> UInt8 {
	return UInt8(randNorm() * 254) + 1
}

let nexus = Nexus()

class Position: Component {
	var x: Int32 = width/2
	var y: Int32 = height/2
}
class Color: Component {
	var r: UInt8 = randColor()
	var g: UInt8 = randColor()
	var b: UInt8 = randColor()
}

func createScene() {

	let numEntities: Int = 10_000

	for i in 0..<numEntities {
		let e = nexus.create(entity: "\(i)")
		e.assign(Position())
		e.assign(Color())
	}
}

class PositionSystem {
	let family = nexus.family(requiresAll: [Position.self], excludesAll: [])
	var acceleration: Double = 4.0
	func update() {
		family.iterate(components: Position.self) { [unowned self](_, pos) in

			let deltaX: Double = self.acceleration*((randNorm() * 2) - 1)
			let deltaY: Double = self.acceleration*((randNorm() * 2) - 1)
			var x = pos!.x + Int32(deltaX)
			var y = pos!.y + Int32(deltaY)

			if x < 0 || x > width {
				x = -x
			}
			if y < 0 || y > height {
				y = -y
			}

			pos!.x = x
			pos!.y = y
		}
	}

}

class PositionResetSystem {
	let family = nexus.family(requiresAll: [Position.self], excludesAll: [])

	func update() {
		family.iterate(components: Position.self) { (_, pos) in
			pos!.x = width/2
			pos!.y = height/2
		}
	}
}

class ColorSystem {
	let family = nexus.family(requiresAll: [Color.self], excludesAll: [])

	func update() {
		family.iterate(components: Color.self) { (_, color) in

			color!.r = randColor()
			color!.g = randColor()
			color!.b = randColor()
		}
	}
}

class RenderSystem {
	let hRenderer: OpaquePointer?
	let family = nexus.family(requiresAll: [Position.self, Color.self], excludesAll: [])

	init(hWin: OpaquePointer?) {
		hRenderer = SDL_CreateRenderer(hWin, -1, SDL_RENDERER_ACCELERATED.rawValue)
		if hRenderer == nil {
			SDL_DestroyWindow(hWin)
			SDL_Quit()
			fatalError("could not create renderer")
		}
	}

	deinit {
		SDL_DestroyRenderer(hRenderer)
	}

	func render() {

		SDL_SetRenderDrawColor( hRenderer, 0, 0, 0, 255 ) // black
		SDL_RenderClear(hRenderer) // clear screen

		family.iterate(components: Position.self, Color.self) { [unowned self] (_, pos, color) in
			var rect = SDL_Rect(x: pos!.x, y: pos!.y, w: 2, h: 2)

			SDL_SetRenderDrawColor(self.hRenderer, color!.r, color!.g, color!.b, 255)
			SDL_RenderFillRect(self.hRenderer, &rect)
		}

		SDL_RenderPresent(hRenderer)
	}
}
let positionSystem = PositionSystem()
let positionResetSystem = PositionResetSystem()
let renderSystem = RenderSystem(hWin: hWin)
let colorSystem = ColorSystem()

createScene()

var event: SDL_Event = SDL_Event()
var quit: Bool = false
while quit == false {
	while SDL_PollEvent(&event) == 1 {
		switch SDL_EventType(rawValue: event.type) {
		case SDL_QUIT:
			quit = true
			break
		case SDL_KEYDOWN:
			switch Int(event.key.keysym.sym) {
			case SDLK_ESCAPE:
				quit = true
				break
			case SDLK_c:
				colorSystem.update()
			case SDLK_r:
				positionResetSystem.update()
			case SDLK_s:
				positionSystem.acceleration = 0.0
			case SDLK_PLUS:
				positionSystem.acceleration += 0.1
			case SDLK_MINUS:
				positionSystem.acceleration -= 0.1
			case SDLK_SPACE:
				positionSystem.acceleration = 4.0
			default:
				break
			}
		default:
			break
		}
	}

	positionSystem.update()

	renderSystem.render()
}

SDL_DestroyWindow(hWin)
SDL_Quit()