github.com/xyproto/orbiton/v2@v2.65.12-0.20240516144430-e10a419274ec/game.go

package main

import (
	"bytes"
	"fmt"
	"image"
	"image/draw"
	"image/png"
	"math"
	"math/rand"
	"os"
	"os/signal"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"
	"time"

	"github.com/xyproto/files"
	"github.com/xyproto/vt100"
)

// There is a tradition for including silly little games in editors, so here goes:

const (
	bobRuneLarge      = 'O'
	bobRuneSmall      = 'o'
	evilGobblerRune   = '€'
	bubbleRune        = '°'
	gobblerRune       = 'G'
	gobblerDeadRune   = 'T'
	gobblerZombieRune = '@'
	bobWonRune        = 'Y'
	bobLostRune       = 'n'
	pelletRune        = '¤'
)

var (
	highScoreFile = filepath.Join(userCacheDir, "o", "highscore.txt")

	bobColor             = vt100.LightYellow
	bobWonColor          = vt100.LightGreen
	bobLostColor         = vt100.Red
	evilGobblerColor     = vt100.LightRed
	gobblerColor         = vt100.Yellow
	gobblerDeadColor     = vt100.DarkGray
	gobblerZombieColor   = vt100.LightBlue
	bubbleColor          = vt100.Magenta
	pelletColor1         = vt100.LightGreen
	pelletColor2         = vt100.Green
	statusTextColor      = vt100.Black
	statusTextBackground = vt100.Blue
	resizeColor          = vt100.LightMagenta
	gameBackgroundColor  = vt100.DefaultBackground
)

// Bob represents the player
type Bob struct {
	color      vt100.AttributeColor // foreground color
	x, y       int                  // current position
	oldx, oldy int                  // previous position
	w, h       float64
	state      rune // looks
}

// NewBob creates a new Bob struct
func NewBob(c *vt100.Canvas, startingWidth int) *Bob {
	return &Bob{
		x:     startingWidth / 20,
		y:     10,
		oldx:  startingWidth / 20,
		oldy:  10,
		state: bobRuneSmall,
		color: bobColor,
		w:     float64(c.W()),
		h:     float64(c.H()),
	}
}

// ToggleState changes the look of Bob as he moves
func (b *Bob) ToggleState() {
	const up = bobRuneLarge
	const down = bobRuneSmall
	if b.state == up {
		b.state = down
	} else {
		b.state = up
	}
}

// Draw is called when Bob should be drawn on the canvas
func (b *Bob) Draw(c *vt100.Canvas) {
	c.PlotColor(uint(b.x), uint(b.y), b.color, b.state)
}

// Right is called when Bob should move right
func (b *Bob) Right() bool {
	oldx := b.x
	b.x++
	if b.x >= int(b.w) {
		b.x--
		return false
	}
	b.oldx = oldx
	b.oldy = b.y
	return true
}

// Left is called when Bob should move left
func (b *Bob) Left() bool {
	oldx := b.x
	if b.x-1 < 0 {
		return false
	}
	b.x--
	b.oldx = oldx
	b.oldy = b.y
	return true
}

// Up is called when Bob should move up
func (b *Bob) Up() bool {
	oldy := b.y
	if b.y-1 <= 0 {
		return false
	}
	b.y--
	b.oldx = b.x
	b.oldy = oldy
	return true
}

// Down is called when Bob should move down
func (b *Bob) Down(c *vt100.Canvas) bool {
	oldy := b.y
	b.y++
	if b.y >= int(c.H()) {
		b.y--
		return false
	}
	b.oldx = b.x
	b.oldy = oldy
	return true
}

// Resize is called when the terminal is resized
func (b *Bob) Resize(c *vt100.Canvas) {
	b.color = resizeColor
	b.w = float64(c.W())
	b.h = float64(c.H())
}

// Pellet represents a pellet that can both feed Gobblers and hit the EvilGobbler
type Pellet struct {
	color       vt100.AttributeColor // foreground color
	lifeCounter int
	oldx, oldy  int // previous position
	vx, vy      int // velocity
	x, y        int // current position
	w, h        float64
	state       rune // looks
	removed     bool // to be removed
	stopped     bool // is the movement stopped?
}

// NewPellet creates a new Pellet struct, with position and speed
func NewPellet(c *vt100.Canvas, x, y, vx, vy int) *Pellet {
	return &Pellet{
		x:           x,
		y:           y,
		oldx:        x,
		oldy:        y,
		vx:          vx,
		vy:          vy,
		state:       pelletRune,
		color:       pelletColor1,
		stopped:     false,
		removed:     false,
		lifeCounter: 0,
		w:           float64(c.W()),
		h:           float64(c.H()),
	}
}

// ToggleColor will alternate the colors for this Pellet
func (b *Pellet) ToggleColor() {
	c1 := pelletColor1
	c2 := pelletColor2
	if b.color.Equal(c1) {
		b.color = c2
	} else {
		b.color = c1
	}
}

// Draw draws the Pellet on the canvas
func (b *Pellet) Draw(c *vt100.Canvas) {
	c.PlotColor(uint(b.x), uint(b.y), b.color, b.state)
}

// Next moves the object to the next position, and returns true if it moved
func (b *Pellet) Next(c *vt100.Canvas, e *EvilGobbler) bool {
	b.lifeCounter++
	if b.lifeCounter > 20 {
		b.removed = true
		b.ToggleColor()
		return false
	}

	if b.stopped {
		b.ToggleColor()
		return false
	}
	if b.x-b.vx < 0 {
		b.ToggleColor()
		return false
	}
	if b.y-b.vy < 0 {
		b.ToggleColor()
		return false
	}

	b.oldx = b.x
	b.oldy = b.y

	b.x += b.vx
	b.y += b.vy

	if b.x == e.x && b.y == e.y {
		e.shot = true
	}

	if b.HitSomething(c) {
		b.x = b.oldx
		b.y = b.oldy
		return false
	}
	if b.x >= int(b.w) || b.x < 0 {
		b.x -= b.vx
		return false
	}
	if b.y >= int(c.H()) {
		b.y -= b.vy
		return false
	} else if b.y <= 0 {
		b.y -= b.vy
		return false
	}
	return true
}

// Stop is called when the pellet should stop moving
func (b *Pellet) Stop() {
	b.vx = 0
	b.vy = 0
	b.stopped = true
}

// HitSomething is called when the pellet hits something
func (b *Pellet) HitSomething(c *vt100.Canvas) bool {
	r, err := c.At(uint(b.x), uint(b.y))
	if err != nil {
		return false
	}
	if r != rune(0) && r != ' ' {
		// Hit something. Check the next-next position too
		r2, err := c.At(uint(b.x+b.vx), uint(b.y+b.vy))
		if err != nil {
			return true
		}
		if r2 != rune(0) && r2 != ' ' {
			b.Stop()
		}
		return true
	}
	return false
}

// Resize is called when the terminal is resized
func (b *Pellet) Resize(c *vt100.Canvas) {
	b.stopped = false
	b.w = float64(c.W())
	b.h = float64(c.H())
}

// Bubble represents a bubble character that is in the way
type Bubble struct {
	color      vt100.AttributeColor // foreground color
	x, y       int                  // current position
	oldx, oldy int                  // previous position
	w, h       float64
	state      rune // looks
}

// NewBubbles creates n new Bubble structs
func NewBubbles(c *vt100.Canvas, startingWidth int, n int) []*Bubble {
	bubbles := make([]*Bubble, n)
	for i := range bubbles {
		bubbles[i] = NewBubble(c, startingWidth)
	}
	return bubbles
}

// NewBubble creates a new Bubble struct
func NewBubble(c *vt100.Canvas, startingWidth int) *Bubble {
	return &Bubble{
		x:     startingWidth / 5,
		y:     10,
		oldx:  startingWidth / 5,
		oldy:  10,
		state: bubbleRune,
		color: bubbleColor,
		w:     float64(c.W()),
		h:     float64(c.H()),
	}
}

// Draw draws the Bubble on the canvas
func (b *Bubble) Draw(c *vt100.Canvas) {
	c.PlotColor(uint(b.x), uint(b.y), b.color, b.state)
}

// Resize is called when the terminal is resized
func (b *Bubble) Resize(c *vt100.Canvas) {
	b.color = resizeColor
	b.w = float64(c.W())
	b.h = float64(c.H())
}

// Next moves the object to the next position, and returns true if it moved
func (b *Bubble) Next(c *vt100.Canvas, bob *Bob, gobblers *[]*Gobbler) bool {
	b.oldx = b.x
	b.oldy = b.y

	d := distance(bob.x, b.x, bob.y, b.y)
	if d > 10 {
		if b.x < bob.x {
			b.x++
		} else if b.x > bob.x {
			b.x--
		}
		if b.y < bob.y {
			b.y++
		} else if b.y > bob.y {
			b.y--
		}
	} else {
		for {
			dx := b.x - b.oldx
			dy := b.y - b.oldy
			b.x += int(math.Round(float64(dx*3+rand.Intn(5)-2) / float64(4))) // -2, -1, 0, 1, 2
			b.y += int(math.Round(float64(dy*3+rand.Intn(5)-2) / float64(4)))
			if b.x != b.oldx {
				break
			}
			if b.y != b.oldy {
				break
			}
		}
	}

	if b.HitSomething(c) {
		// "Wake up" dead gobblers
		for _, g := range *gobblers {
			if g.x == b.x && g.y == b.y {
				if g.dead {
					g.dead = false
					g.state = gobblerZombieRune
					g.color = gobblerZombieColor
				}
			}
		}
		// step back
		b.x = b.oldx
		b.y = b.oldy
		return false
	}

	if b.x >= int(b.w) {
		b.x = b.oldx
	} else if b.x <= 0 {
		b.x = b.oldx
	}
	if b.y >= int(c.H()) {
		b.y = b.oldy
	} else if b.y <= 0 {
		b.y = b.oldy
	}

	return b.x != b.oldx || b.y != b.oldy
}

// HitSomething is called if the Bubble hits another character
func (b *Bubble) HitSomething(c *vt100.Canvas) bool {
	r, err := c.At(uint(b.x), uint(b.y))
	if err != nil {
		return false
	}
	// Hit something?
	return r != rune(0) && r != ' '
}

// EvilGobbler is a character that hunts Gobblers
type EvilGobbler struct {
	hunting         *Gobbler
	color           vt100.AttributeColor // foreground color
	x, y            int                  // current position
	oldx, oldy      int                  // previous position
	counter         uint
	huntingDistance float64
	w, h            float64
	state           rune // looks
	shot            bool
}

// NewEvilGobbler creates an EvilGobbler struct.
// startingWidth is the initial width of the canvas.
func NewEvilGobbler(c *vt100.Canvas, startingWidth int) *EvilGobbler {
	return &EvilGobbler{
		x:               startingWidth/2 + 5,
		y:               0o1,
		oldx:            startingWidth/2 + 5,
		oldy:            10,
		state:           evilGobblerRune,
		color:           evilGobblerColor,
		counter:         0,
		shot:            false,
		hunting:         nil,
		huntingDistance: 0.0,
		w:               float64(c.W()),
		h:               float64(c.H()),
	}
}

// Draw will draw the EvilGobbler on the canvas
func (e *EvilGobbler) Draw(c *vt100.Canvas) {
	c.PlotColor(uint(e.x), uint(e.y), e.color, e.state)
}

// Next will make the next EvilGobbler move
func (e *EvilGobbler) Next(c *vt100.Canvas, gobblers *[]*Gobbler) bool {
	e.oldx = e.x
	e.oldy = e.y

	minDistance := 0.0
	found := false
	for i, g := range *gobblers {
		if d := distance(g.x, g.y, e.x, e.y); !g.dead && (d < minDistance || minDistance == 0.0) {
			e.hunting = (*gobblers)[i]
			minDistance = d
			found = true
		}
	}
	if found {
		e.huntingDistance = minDistance
	}

	if e.hunting == nil {

		e.x += rand.Intn(3) - 1
		e.y += rand.Intn(3) - 1

	} else {

		xspeed := 1
		yspeed := 1

		if e.x < e.hunting.x {
			e.x += xspeed
		} else if e.x > e.hunting.x {
			e.x -= xspeed
		}
		if e.y < e.hunting.y {
			e.y += yspeed
		} else if e.y > e.hunting.y {
			e.y -= yspeed
		}

		if !e.hunting.dead && e.huntingDistance < 1.8 || (e.hunting.x == e.x && e.hunting.y == e.y) {
			e.hunting.dead = true
			e.counter++
			e.hunting = nil
			e.huntingDistance = 9999.9
		}
	}

	if e.x > int(e.w) {
		e.x = e.oldx
	} else if e.x < 0 {
		e.x = e.oldx
	}

	if e.y > int(c.H()) {
		e.y = e.oldy
	} else if e.y <= 0 {
		e.y = e.oldy
	}

	return (e.x != e.oldx || e.y != e.oldy)
}

// Resize is called when the terminal is resized
func (e *EvilGobbler) Resize(c *vt100.Canvas) {
	e.color = resizeColor
	e.w = float64(c.W())
	e.h = float64(c.H())
}

// Gobbler represents a character that can move around and eat pellets
type Gobbler struct {
	hunting         *Pellet              // current pellet to hunt
	color           vt100.AttributeColor // foreground color
	x, y            int                  // current position
	oldx, oldy      int                  // previous position
	huntingDistance float64              // how far to closest pellet
	counter         uint
	w, h            float64
	state           rune // looks
	dead            bool
}

// NewGobbler creates a new Gobbler struct
func NewGobbler(c *vt100.Canvas, startingWidth int) *Gobbler {
	return &Gobbler{
		x:               startingWidth / 2,
		y:               10,
		oldx:            startingWidth / 2,
		oldy:            10,
		state:           gobblerRune,
		color:           gobblerColor,
		hunting:         nil,
		huntingDistance: 0,
		counter:         0,
		dead:            false,
		w:               float64(c.W()),
		h:               float64(c.H()),
	}
}

// NewGobblers creates n new Gobbler structs
func NewGobblers(c *vt100.Canvas, startingWidth int, n int) []*Gobbler {
	gobblers := make([]*Gobbler, n)
	for i := range gobblers {
		gobblers[i] = NewGobbler(c, startingWidth)
	}
	return gobblers
}

// Draw draws the current Gobbler on the canvas
func (g *Gobbler) Draw(c *vt100.Canvas) {
	c.PlotColor(uint(g.x), uint(g.y), g.color, g.state)
}

// Next is called when the next move should be made
func (g *Gobbler) Next(pellets *[]*Pellet, bob *Bob) bool {
	if g.dead {
		return false
	}

	g.oldx = g.x
	g.oldy = g.y

	xspeed := 1
	yspeed := 1

	// Move to the nearest pellet and eat it
	if len(*pellets) == 0 {

		g.x += rand.Intn(5) - 2
		g.y += rand.Intn(5) - 2

	} else {

		if g.hunting == nil || g.hunting.removed {
			minDistance := 0.0
			var closestPellet *Pellet

			// TODO: Hunt a random pellet that is not already hunted instead of the closest

			for i, b := range *pellets {
				if d := distance(b.x, b.y, g.x, g.y); !b.removed && (minDistance == 0.0 || d < minDistance) {
					closestPellet = (*pellets)[i]
					minDistance = d
				}
			}
			if closestPellet != nil {
				g.hunting = closestPellet
				g.huntingDistance = minDistance
			}
		} else {
			g.huntingDistance = distance(g.hunting.x, g.hunting.y, g.x, g.y)
		}

		if g.hunting == nil {

			g.x += rand.Intn(3) - 1
			g.y += rand.Intn(3) - 1

		} else {

			if abs(g.hunting.x-g.x) >= abs(g.hunting.y-g.y) {
				// Longer away along x than along y
				if g.huntingDistance > 10 {
					xspeed = 3
					yspeed = 2
				} else if g.huntingDistance > 5 {
					xspeed = 2 + rand.Intn(2)
					yspeed = 2
				}
			} else {
				// Longer away along x than along y
				if g.huntingDistance > 10 {
					xspeed = 2
					yspeed = 3
				} else if g.huntingDistance > 5 {
					xspeed = 2
					yspeed = 2 + rand.Intn(2)
				}
			}

			if g.x < g.hunting.x {
				g.x += xspeed
			} else if g.x > g.hunting.x {
				g.x -= xspeed
			}
			if g.y < g.hunting.y {
				g.y += yspeed
			} else if g.y > g.hunting.y {
				g.y -= yspeed
			}

			if distance(bob.x, bob.y, g.x, g.y) < 4 {
				g.x = g.oldx + (rand.Intn(3) - 1)
				g.y = g.oldy + (rand.Intn(3) - 1)
			}

			if !g.hunting.removed && g.huntingDistance < 2 || (g.hunting.x == g.x && g.hunting.y == g.y) {
				g.hunting.removed = true
				g.counter++
				g.hunting = nil
				g.huntingDistance = 9999.9
			}
		}
	}

	if g.x > int(g.w) {
		g.x = int(g.w) - 1
		g.x -= xspeed
	} else if g.x < 0 {
		g.x = 0
		g.x += xspeed
	}

	if g.y > int(g.h) {
		g.y = int(g.h) - 1
		g.y -= yspeed
	} else if g.y <= 0 {
		g.y = 0
		g.y += yspeed
	}

	if g.x <= 2 && g.y >= (int(g.h)-2) {
		// Close to the lower left corner
		g.x = int(g.w) - 1 // teleport!
		g.y = 0            // teleport!
	} else if g.x <= 2 && g.y <= 2 {
		// Close to the upper left corner
		g.x = int(g.w) - 1 // teleport!
		g.y = int(g.h) - 1 // teleport
	}

	return (g.x != g.oldx || g.y != g.oldy)
}

// Resize is called when the terminal is resized
func (g *Gobbler) Resize(c *vt100.Canvas) {
	g.color = resizeColor
	g.w = float64(c.W())
	g.h = float64(c.H())
}

// saveHighScore will save the given high score to a file,
// creating a new file if needed and overwriting the existing highscore
// if it's already there.
func saveHighScore(highScore uint) error {
	if noWriteToCache {
		return nil
	}
	// First create the folders, if needed
	folderPath := filepath.Dir(highScoreFile)
	os.MkdirAll(folderPath, os.ModePerm)
	// Prepare the file
	f, err := os.OpenFile(highScoreFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0o600)
	if err != nil {
		return err
	}
	defer f.Close()
	// Write the contents, ignore the number of written bytes
	_, err = f.WriteString(fmt.Sprintf("%d\n", highScore))
	return err
}

// loadHighScore will load the current high score from the highScoreFile,
// if possible.
func loadHighScore() (uint, error) {
	data, err := os.ReadFile(highScoreFile)
	if err != nil {
		return 0, err
	}
	highScoreString := string(bytes.TrimSpace(data))
	highScore, err := strconv.ParseUint(highScoreString, 10, 64)
	if err != nil {
		return 0, err
	}
	return uint(highScore), nil
}

// Game starts the game and returns true if ctrl-q was pressed
func Game() (bool, error) {
retry:
	if envNoColor {
		bobColor = vt100.White
		bobWonColor = vt100.LightGray
		bobLostColor = vt100.DarkGray
		evilGobblerColor = vt100.White
		gobblerColor = vt100.LightGray
		gobblerDeadColor = vt100.DarkGray
		bubbleColor = vt100.DarkGray
		pelletColor1 = vt100.White
		pelletColor2 = vt100.White
		statusTextColor = vt100.Black
		statusTextBackground = vt100.LightGray
		resizeColor = vt100.White
		gameBackgroundColor = vt100.DefaultBackground
	} else {
		statusTextBackground = vt100.Blue
		bobColor = vt100.LightYellow
	}

	// Try loading the highscore from the file, but ignore any errors
	highScore, _ := loadHighScore()

	c := vt100.NewCanvas()
	c.FillBackground(gameBackgroundColor)

	tty, err := vt100.NewTTY()
	if err != nil {
		fmt.Fprintln(os.Stderr, "error: "+err.Error())
		quitMut.Lock()
		defer quitMut.Unlock()
		os.Exit(1)
	}
	defer tty.Close()

	tty.SetTimeout(2 * time.Millisecond)

	var (
		sigChan       = make(chan os.Signal, 1)
		startingWidth = int(c.W())
		bob           = NewBob(c, startingWidth)
		evilGobbler   = NewEvilGobbler(c, startingWidth)
		gobblers      = NewGobblers(c, startingWidth, 25)
		pellets       = make([]*Pellet, 0)
		bubbles       = NewBubbles(c, startingWidth, 15)
		score         = uint(0)
	)

	signal.Notify(sigChan, syscall.SIGWINCH)
	go func() {
		for range sigChan {
			resizeMut.Lock()
			// Create a new canvas, with the new size
			nc := c.Resized()
			if nc != nil {
				c.Clear()
				vt100.Clear()
				c.Draw()
				c = nc
			}

			// Inform all elements that the terminal was resized
			// TODO: Use a slice of interfaces that can contain all elements
			for _, pellet := range pellets {
				pellet.Resize(c)
			}
			for _, bubble := range bubbles {
				bubble.Resize(c)
			}
			for _, gobbler := range gobblers {
				gobbler.Resize(c)
			}
			bob.Resize(c)
			evilGobbler.Resize(c)
			resizeMut.Unlock()
		}
	}()

	vt100.Init()
	vt100.EchoOff()
	defer vt100.Close()

	// The loop time that is aimed for
	var (
		loopDuration  = time.Millisecond * 10
		start         = time.Now()
		running       = true
		paused        bool
		statusText    string
		key           int
		gobblersAlive int
	)

	// Don't output keypress terminal codes on the screen
	tty.NoBlock()

	for running {

		// Draw elements in their new positions
		c.Clear()
		// c.Draw()

		resizeMut.RLock()
		for _, pellet := range pellets {
			pellet.Draw(c)
		}
		for _, bubble := range bubbles {
			bubble.Draw(c)
		}
		evilGobbler.Draw(c)
		for _, gobbler := range gobblers {
			gobbler.Draw(c)
		}
		bob.Draw(c)
		centerStatus := "Feed the gobblers"
		rightStatus := fmt.Sprintf("%d alive", gobblersAlive)
		statusLineLength := int(c.W())
		statusLine := " " + statusText

		if !paused && statusLineLength-(len(" "+statusText)+len(rightStatus+" ")) > (len(rightStatus+" ")+len(centerStatus)) {
			paddingLength := statusLineLength - (len(" "+statusText) + len(centerStatus) + len(rightStatus+" "))
			centerLeftLength := int(math.Floor(float64(paddingLength) / 2.0))
			centerRightLength := int(math.Ceil(float64(paddingLength) / 2.0))
			statusLine += strings.Repeat(" ", centerLeftLength) // padding left of center
			statusLine += centerStatus
			statusLine += strings.Repeat(" ", centerRightLength) // padding right of center
			statusLine += rightStatus + " "
		} else if statusLineLength-len(" "+statusText) > len(rightStatus+" ") {
			paddingLength := statusLineLength - (len(" "+statusText) + len(rightStatus+" "))
			statusLine += strings.Repeat(" ", paddingLength) // center padding
			statusLine += rightStatus + " "
		} else {
			paddingLength := statusLineLength - len(" "+statusText)
			statusLine += strings.Repeat("-", paddingLength)
		}

		c.Write(0, 0, statusTextColor, statusTextBackground, statusLine)
		resizeMut.RUnlock()

		// vt100.Clear()

		// Update the canvas
		c.Draw()

		// Wait a bit
		end := time.Now()
		passed := end.Sub(start)
		if passed < loopDuration {
			remaining := loopDuration - passed
			time.Sleep(remaining)
		}
		start = time.Now()

		// Has the player moved?
		moved := false

		// Handle events
		key = tty.Key()
		switch key {
		case 253, 119: // Up or w
			resizeMut.Lock()
			moved = bob.Up()
			resizeMut.Unlock()
		case 255, 115: // Down or s
			resizeMut.Lock()
			moved = bob.Down(c)
			resizeMut.Unlock()
		case 254, 100: // Right or d
			resizeMut.Lock()
			moved = bob.Right()
			resizeMut.Unlock()
		case 252, 97: // Left or a
			resizeMut.Lock()
			moved = bob.Left()
			resizeMut.Unlock()
		case 114: // r
			goto retry
		case 113: // q
			dx := 1
			dy := 1
			// Fire eight new pellets
			pellets = append(pellets, NewPellet(c, bob.x+dx, bob.y+dx, dx, dy))
			pellets = append(pellets, NewPellet(c, bob.x-dx, bob.y+dy, -dx, dy))
			pellets = append(pellets, NewPellet(c, bob.x+dx, bob.y-dy, dx, -dy))
			pellets = append(pellets, NewPellet(c, bob.x-dx, bob.y-dy, -dx, -dy))
			pellets = append(pellets, NewPellet(c, bob.x+dx, bob.y, dx, 0))
			pellets = append(pellets, NewPellet(c, bob.x-dx, bob.y, -dx, 0))
			pellets = append(pellets, NewPellet(c, bob.x, bob.y-dy, 0, -dy))
			pellets = append(pellets, NewPellet(c, bob.x, bob.y-dy, 0, -dy))
		case 27: // ESC
			running = false
		case 17: // ctrl-q
			return true, nil

		case 19: // ctrl-s
			// Save a screenshot
			// Use c.ToImage to generate the image
			originalImg, err := c.ToImage()
			if err != nil {
				statusText = "error: " + err.Error()
				break
			}
			// Create a new image without the first 8 rows
			bounds := originalImg.Bounds()
			newImg := image.NewRGBA(image.Rect(0, 0, bounds.Dx(), bounds.Dy()-8))
			draw.Draw(newImg, newImg.Bounds(), originalImg, image.Point{0, 8}, draw.Src)
			// Create the file
			screenshotFilename := files.TimestampedFilename("orbiton.png")
			f, err := os.Create(screenshotFilename)
			if err != nil {
				statusText = "error: " + err.Error()
				break
			}
			defer f.Close()
			// Encode and save the image
			err = png.Encode(f, newImg)
			if err != nil {
				statusText = "error: " + err.Error()
				break
			}
			// Done
			statusText = "Wrote " + screenshotFilename
		case 32: // Space
			if !paused {
				// Fire a new pellet
				pellets = append(pellets, NewPellet(c, bob.x, bob.y, bob.x-bob.oldx, bob.y-bob.oldy))
			} else {
				// Progress the pellets, just for entertainment
				for _, pellet := range pellets {
					pellet.Next(c, evilGobbler)
				}
			}
		}

		if !paused {
			// Change state
			resizeMut.Lock()
			for _, pellet := range pellets {
				pellet.Next(c, evilGobbler)
			}
			for _, bubble := range bubbles {
				bubble.Next(c, bob, &gobblers)
			}
			for _, gobbler := range gobblers {
				gobbler.Next(&pellets, bob)
			}
			evilGobbler.Next(c, &gobblers)
			if moved {
				bob.ToggleState()
			}
			resizeMut.Unlock()
		}
		// Erase all previous positions not occupied by current items
		c.Plot(uint(bob.oldx), uint(bob.oldy), ' ')
		c.Plot(uint(evilGobbler.oldx), uint(evilGobbler.oldy), ' ')
		for _, pellet := range pellets {
			c.Plot(uint(pellet.oldx), uint(pellet.oldy), ' ')
		}
		for _, bubble := range bubbles {
			c.Plot(uint(bubble.oldx), uint(bubble.oldy), ' ')
		}
		for _, gobbler := range gobblers {
			c.Plot(uint(gobbler.oldx), uint(gobbler.oldy), ' ')
		}

		// Clean up removed pellets
		filteredPellets := make([]*Pellet, 0, len(pellets))
		for _, pellet := range pellets {
			if !pellet.removed {
				filteredPellets = append(filteredPellets, pellet)
			} else {
				c.Plot(uint(pellet.x), uint(pellet.y), ' ')
			}
		}
		pellets = filteredPellets

		if !paused {

			gobblersAlive = 0
			for _, gobbler := range gobblers {
				score += gobbler.counter
				gobbler.counter = 0
				if !gobbler.dead {
					gobblersAlive++
				} else {
					gobbler.state = gobblerDeadRune
					gobbler.color = gobblerDeadColor
				}
			}
			if gobblersAlive > 0 {
				statusText = fmt.Sprintf("Score: %d", score)
			} else if gobblersAlive > 0 && evilGobbler.shot {
				paused = true
				statusText = "You won!"

				// The player can still move around bob
				bob.state = bobWonRune

				if !envNoColor {
					bob.color = bobWonColor
					statusTextBackground = bobWonColor
				}

				if score > highScore {
					statusText = fmt.Sprintf("You won! New highscore: %d", score)
					saveHighScore(score)
				} else if score > 0 {
					statusText = fmt.Sprintf("You won! Score: %d", score)
				}
			} else {
				paused = true
				statusText = "Game over"

				// The player can still move around bob
				bob.state = bobLostRune

				if !envNoColor {
					bob.color = bobLostColor
					statusTextBackground = bobLostColor
				}

				if score > highScore {
					statusText = fmt.Sprintf("Game over! New highscore: %d - press r to retry - press ctrl-s to save a screenshot", score)
					saveHighScore(score)
				} else if score > 0 {
					statusText = fmt.Sprintf("Game over! Score: %d - press r to retry", score)
				}
			}
		}
	}
	return false, nil
}