examples: Add comments

examples/highdpi/main.go

@@ -33,7 +33,7 @@ var (
 )
 
 func init() {
-	// licensed under Public Domain
+	// Licensed under Public Domain
 	// https://commons.wikimedia.org/wiki/File:As08-16-2593.jpg
 	const url = "https://upload.wikimedia.org/wikipedia/commons/1/1f/As08-16-2593.jpg"
 

examples/hsv/main.go

@@ -32,15 +32,17 @@ const (
 )
 
 var (
-	hueInt        = 0
-	saturationInt = 128
-	valueInt      = 128
+	hue128        = 0
+	saturation128 = 128
+	value128      = 128
+
 	inverted = false
 
 	prevPressedI = false
 	gophersImage *ebiten.Image
 )
 
+// clamp clamps v to the range [min, max].
 func clamp(v, min, max int) int {
 	if min > max {
 		panic("min must <= max")
@@ -55,25 +57,30 @@ func clamp(v, min, max int) int {
 }
 
 func update(screen *ebiten.Image) error {
+	// Adjust HSV values along with the user's input.
 	if ebiten.IsKeyPressed(ebiten.KeyQ) {
-		hueInt--
+		hue128--
 	}
 	if ebiten.IsKeyPressed(ebiten.KeyW) {
-		hueInt++
+		hue128++
 	}
 	if ebiten.IsKeyPressed(ebiten.KeyA) {
-		saturationInt--
+		saturation128--
 	}
 	if ebiten.IsKeyPressed(ebiten.KeyS) {
-		saturationInt++
+		saturation128++
 	}
 	if ebiten.IsKeyPressed(ebiten.KeyZ) {
-		valueInt--
+		value128--
 	}
 	if ebiten.IsKeyPressed(ebiten.KeyX) {
-		valueInt++
+		value128++
 	}
 
+	hue128 = clamp(hue128, -256, 256)
+	saturation128 = clamp(saturation128, 0, 256)
+	value128 = clamp(value128, 0, 256)
+
 	pressedI := ebiten.IsKeyPressed(ebiten.KeyI)
 	if pressedI && !prevPressedI {
 		inverted = !inverted
@@ -83,18 +90,19 @@ func update(screen *ebiten.Image) error {
 	if ebiten.IsRunningSlowly() {
 		return nil
 	}
-	hueInt = clamp(hueInt, -256, 256)
-	saturationInt = clamp(saturationInt, 0, 256)
-	valueInt = clamp(valueInt, 0, 256)
 
+	// Center the image on the screen.
 	w, h := gophersImage.Size()
 	op := &ebiten.DrawImageOptions{}
 	op.GeoM.Translate(float64(screenWidth-w)/2, float64(screenHeight-h)/2)
 
-	hue := float64(hueInt) * 2 * math.Pi / 128
-	saturation := float64(saturationInt) / 128
-	value := float64(valueInt) / 128
+	// Change HSV.
+	hue := float64(hue128) * 2 * math.Pi / 128
+	saturation := float64(saturation128) / 128
+	value := float64(value128) / 128
 	op.ColorM.ChangeHSV(hue, saturation, value)
+
+	// Invert the color.
 	if inverted {
 		op.ColorM.Scale(-1, -1, -1, 1)
 		op.ColorM.Translate(1, 1, 1, 0)
@@ -102,6 +110,7 @@ func update(screen *ebiten.Image) error {
 
 	screen.DrawImage(gophersImage, op)
 
+	// Draw the text of the current status.
 	msgInverted := "false"
 	if inverted {
 		msgInverted = "true"

examples/hue/main.go

@@ -37,13 +37,19 @@ var (
 
 func update(screen *ebiten.Image) error {
 	count++
+
 	if ebiten.IsRunningSlowly() {
 		return nil
 	}
+
+	// Center the image on the screen.
 	w, h := gophersImage.Size()
 	op := &ebiten.DrawImageOptions{}
 	op.GeoM.Translate(float64(screenWidth-w)/2, float64(screenHeight-h)/2)
+
+	// Rotate the hue.
 	op.ColorM.RotateHue(float64(count%360) * 2 * math.Pi / 360)
+
 	screen.DrawImage(gophersImage, op)
 	return nil
 }

examples/life/main.go

@@ -33,13 +33,13 @@ import (
 	"github.com/hajimehoshi/ebiten"
 )
 
-// World represents the game state
+// World represents the game state.
 type World struct {
 	area [][]bool
 	rnd  *rand.Rand
 }
 
-// NewWorld creates a new world
+// NewWorld creates a new world.
 func NewWorld(width, height int) *World {
 	world := World{
 		area: makeArea(width, height),
@@ -48,7 +48,7 @@ func NewWorld(width, height int) *World {
 	return &world
 }
 
-// RandomSeed inits world with a random state
+// RandomSeed inits world with a random state.
 func (w *World) RandomSeed(limit int) {
 	height := len(w.area)
 	width := len(w.area[0])
@@ -59,14 +59,13 @@ func (w *World) RandomSeed(limit int) {
 	}
 }
 
-// Progress game state by one tick
-func (w *World) Progress() {
+// Update game state by one tick.
+func (w *World) Update() {
 	height := len(w.area)
 	width := len(w.area[0])
 	next := makeArea(width, height)
 	for y := 0; y < height; y++ {
 		for x := 0; x < width; x++ {
-
 			pop := neighbourCount(w.area, x, y)
 			switch {
 			case pop < 2:
@@ -95,7 +94,7 @@ func (w *World) Progress() {
 }
 
 // DrawImage paints current game state
-func (w *World) DrawImage(pix []uint8) {
+func (w *World) DrawImage(pix []byte) {
 	height := len(w.area)
 	width := len(w.area[0])
 	for y := 0; y < height; y++ {
@@ -116,7 +115,7 @@ func (w *World) DrawImage(pix []uint8) {
 	}
 }
 
-// neighbourCount calculates the Moore neighborhood of x, y
+// neighbourCount calculates the Moore neighborhood of (x, y)
 func neighbourCount(a [][]bool, x, y int) int {
 	height := len(a)
 	width := len(a[0])
@@ -163,11 +162,11 @@ const (
 
 var (
 	world  = NewWorld(screenWidth, screenHeight)
-	pixels = make([]uint8, screenWidth*screenHeight*4)
+	pixels = make([]byte, screenWidth*screenHeight*4)
 )
 
 func update(screen *ebiten.Image) error {
-	world.Progress()
+	world.Update()
 	if ebiten.IsRunningSlowly() {
 		return nil
 	}