lifegame.go

package main

import (
	"math/rand"
	"time"

	"github.com/nsf/termbox-go"
)

const (
	coldef = termbox.ColorDefault
	death  = 0
	alive  = 1
)

// Earth ...
type Earth struct {
	width  int
	height int
	field  [][]int
}

// InitEarth ...
func (e *Earth) InitEarth(h, w int) {
	e.width = w
	e.height = h
	e.field = make([][]int, h)
	for i := 0; i < h; i++ {
		e.field[i] = make([]int, w)
	}
}

// RandEarth ...
func (e *Earth) RandEarth() {
	for j := 0; j < e.height; j++ {
		for i := 0; i < e.width; i++ {
			e.field[j][i] = rand.Intn(2)
		}
	}
}

// DrawField ...
func (e Earth) DrawField() {
	for j := 0; j < e.height; j++ {
		for i := 0; i < e.width; i++ {
			if e.field[j][i] == death {
				termbox.SetCell(i*2, j, '⚪', coldef, coldef)
			} else {
				termbox.SetCell(i*2, j, '🔴', coldef, coldef)
			}
		}
	}
	termbox.Flush()
}

// Digenesis ...
func (e Earth) Digenesis() Earth {
	var child Earth
	child.InitEarth(e.height, e.width)

	for j := 0; j < e.height; j++ {
		for i := 0; i < e.width; i++ {
			sibs := countSibs(j, i, e)
			if e.field[j][i] == death {
				// 誕生: 死んでいるセルに隣接する生きたセルがちょうど3つあれば、次の世代が誕生する。
				if sibs == 3 {
					child.field[j][i] = alive
				}
			} else {
				// 生存: 生きているセルに隣接する生きたセルが2つか3つならば、次の世代でも生存する。
				// 過疎: 生きているセルに隣接する生きたセルが1つ以下ならば、過疎により死滅する。
				// 過密: 生きているセルに隣接する生きたセルが4つ以上ならば、過密により死滅する。
				if sibs == 2 || sibs == 3 {
					child.field[j][i] = alive
				} else {
					child.field[j][i] = death
				}
			}
		}
	}
	return child
}

// SetDress ...
func (e Earth) SetDress() Earth {
	var ee Earth
	ee.InitEarth(e.height, e.width)
	ee.width += 2
	ee.height += 2
	for i, v := range e.field {
		ee.field[i] = append(make([]int, 1), append(v, 0)...)
	}
	ee.field = append([][]int{make([]int, ee.width)}, ee.field...)
	ee.field = append(ee.field, make([]int, ee.width))
	return ee
}

func countSibs(y, x int, e Earth) int {
	var sibs int
	dressed := e.SetDress()

	sibs += dressed.field[y][x]     // ↖︎
	sibs += dressed.field[y][x+1]   // ↑
	sibs += dressed.field[y][x+2]   // ↗︎
	sibs += dressed.field[y+1][x]   // ←
	sibs += dressed.field[y+1][x+2] // →
	sibs += dressed.field[y+2][x]   // ↙︎
	sibs += dressed.field[y+2][x+1] // ↓
	sibs += dressed.field[y+2][x+2] // ↘︎
	return sibs
}

//key events
func keyEventLoop(kch chan termbox.Key) {
	for {
		switch ev := termbox.PollEvent(); ev.Type {
		case termbox.EventKey:
			kch <- ev.Key
		default:
		}
	}
}

//timer event
func timerLoop(tch chan bool, span int) {
	for {
		tch <- true
		time.Sleep(time.Duration(span) * time.Millisecond)
	}
}

func mainLoop(et Earth, tch chan bool, kch chan termbox.Key) {
	for {
		select {
		case key := <-kch: //key event
			switch key {
			case termbox.KeyEsc, termbox.KeyCtrlC: //end event
				return
			case termbox.KeySpace:
				et.RandEarth()
			}
		case <-tch: //time event
			et = et.Digenesis()
			et.DrawField()
			break
		default:
		}
	}
}

func main() {
	err := termbox.Init()
	if err != nil {
		panic(err)
	}
	defer termbox.Close()

	rand.Seed(time.Now().UnixNano())

	var earth Earth
	earth.InitEarth(25, 25)
	earth.RandEarth()

	kch := make(chan termbox.Key)
	tch := make(chan bool)
	go keyEventLoop(kch)
	go timerLoop(tch, 100)

	mainLoop(earth, tch, kch)
}