From 4bccf9d0092e71cb9a4b43e4fe3abef62c9ac373 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Thu, 12 Sep 2024 01:03:53 +0900
Subject: [PATCH] all: use math/rand/v2

---
 audio/internal/convert/float32_test.go   |  4 ++--
 audio/internal/convert/stereof32_test.go |  2 +-
 audio/internal/convert/stereoi16_test.go |  6 +++---
 examples/2048/2048/game.go               |  7 -------
 examples/2048/2048/tile.go               |  6 +++---
 examples/blocks/blocks/gamescene.go      |  9 ++-------
 examples/chipmunk/main.go                |  2 +-
 examples/doomfire/main.go                |  7 ++-----
 examples/drag/main.go                    | 11 +++--------
 examples/flappy/main.go                  |  9 ++-------
 examples/font/main.go                    | 15 +++++----------
 examples/isometric/level.go              |  8 ++------
 examples/life/main.go                    | 11 +++--------
 examples/mascot/main.go                  | 11 +++--------
 examples/particles/main.go               | 11 +++--------
 examples/set/main.go                     | 17 ++++++-----------
 examples/snake/main.go                   | 11 +++--------
 examples/sprites/main.go                 |  8 ++++----
 examples/spriteshd/main.go               |  8 ++++----
 examples/squiral/main.go                 | 19 +++++++------------
 examples/stars/main.go                   |  4 +---
 examples/windowsize/main.go              | 10 ++++------
 image_test.go                            |  9 ++-------
 internal/affine/colorm_test.go           |  2 +-
 24 files changed, 67 insertions(+), 140 deletions(-)

diff --git a/audio/internal/convert/float32_test.go b/audio/internal/convert/float32_test.go
index 8d48e33fc..658571961 100644
--- a/audio/internal/convert/float32_test.go
+++ b/audio/internal/convert/float32_test.go
@@ -17,7 +17,7 @@ package convert_test
 import (
 	"bytes"
 	"io"
-	"math/rand" // TODO: Use math/rand/v2 when the minimum supported version becomes Go 1.22.
+	"math/rand/v2"
 	"testing"
 	"unsafe"
 
@@ -27,7 +27,7 @@ import (
 func randInt16s(n int) []int16 {
 	r := make([]int16, n)
 	for i := range r {
-		r[i] = int16(rand.Intn(1<<16) - (1 << 15))
+		r[i] = int16(rand.IntN(1<<16) - (1 << 15))
 	}
 	return r
 }
diff --git a/audio/internal/convert/stereof32_test.go b/audio/internal/convert/stereof32_test.go
index e992e510c..e1dfd8fad 100644
--- a/audio/internal/convert/stereof32_test.go
+++ b/audio/internal/convert/stereof32_test.go
@@ -19,7 +19,7 @@ import (
 	"fmt"
 	"io"
 	"math"
-	"math/rand" // TODO: Use math/rand/v2 when the minimum supported version becomes Go 1.22.
+	"math/rand/v2"
 	"testing"
 
 	"github.com/hajimehoshi/ebiten/v2/audio/internal/convert"
diff --git a/audio/internal/convert/stereoi16_test.go b/audio/internal/convert/stereoi16_test.go
index fe5c746a0..f5338e10c 100644
--- a/audio/internal/convert/stereoi16_test.go
+++ b/audio/internal/convert/stereoi16_test.go
@@ -17,8 +17,8 @@ package convert_test
 import (
 	"bytes"
 	"fmt"
-	"io" // TODO: Use math/rand/v2 when the minimum supported version becomes Go 1.22.
-	"math/rand"
+	"io"
+	"math/rand/v2"
 	"testing"
 
 	"github.com/hajimehoshi/ebiten/v2/audio/internal/convert"
@@ -101,7 +101,7 @@ func TestStereoI16(t *testing.T) {
 func randBytes(n int) []byte {
 	r := make([]byte, n)
 	for i := range r {
-		r[i] = byte(rand.Intn(256))
+		r[i] = byte(rand.IntN(256))
 	}
 	return r
 }
diff --git a/examples/2048/2048/game.go b/examples/2048/2048/game.go
index dcb1ec482..d4f53589c 100644
--- a/examples/2048/2048/game.go
+++ b/examples/2048/2048/game.go
@@ -15,16 +15,9 @@
 package twenty48
 
 import (
-	"math/rand"
-	"time"
-
 	"github.com/hajimehoshi/ebiten/v2"
 )
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 const (
 	ScreenWidth  = 420
 	ScreenHeight = 600
diff --git a/examples/2048/2048/tile.go b/examples/2048/2048/tile.go
index fe44e8f94..0c1d04881 100644
--- a/examples/2048/2048/tile.go
+++ b/examples/2048/2048/tile.go
@@ -19,7 +19,7 @@ import (
 	"errors"
 	"image/color"
 	"log"
-	"math/rand"
+	"math/rand/v2"
 	"sort"
 	"strconv"
 
@@ -261,9 +261,9 @@ func addRandomTile(tiles map[*Tile]struct{}, size int) error {
 	if len(availableCells) == 0 {
 		return errors.New("twenty48: there is no space to add a new tile")
 	}
-	c := availableCells[rand.Intn(len(availableCells))]
+	c := availableCells[rand.IntN(len(availableCells))]
 	v := 2
-	if rand.Intn(10) == 0 {
+	if rand.IntN(10) == 0 {
 		v = 4
 	}
 	x := c % size
diff --git a/examples/blocks/blocks/gamescene.go b/examples/blocks/blocks/gamescene.go
index 19e0d206d..cc8647378 100644
--- a/examples/blocks/blocks/gamescene.go
+++ b/examples/blocks/blocks/gamescene.go
@@ -20,9 +20,8 @@ import (
 	"image/color"
 	_ "image/jpeg"
 	_ "image/png"
-	"math/rand"
+	"math/rand/v2"
 	"strconv"
-	"time"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/colorm"
@@ -139,10 +138,6 @@ type GameScene struct {
 	gameover           bool
 }
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 func NewGameScene() *GameScene {
 	return &GameScene{
 		field: &Field{},
@@ -194,7 +189,7 @@ const (
 
 func (s *GameScene) choosePiece() *Piece {
 	num := int(BlockTypeMax)
-	blockType := BlockType(rand.Intn(num) + 1)
+	blockType := BlockType(rand.IntN(num) + 1)
 	return Pieces[blockType]
 }
 
diff --git a/examples/chipmunk/main.go b/examples/chipmunk/main.go
index 8912ec112..f9bf85e43 100644
--- a/examples/chipmunk/main.go
+++ b/examples/chipmunk/main.go
@@ -18,7 +18,7 @@ import (
 	"fmt"
 	"image/color"
 	"log"
-	"math/rand"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
diff --git a/examples/doomfire/main.go b/examples/doomfire/main.go
index e27e333db..d756e860a 100644
--- a/examples/doomfire/main.go
+++ b/examples/doomfire/main.go
@@ -17,8 +17,7 @@ package main
 import (
 	"image/color"
 	"log"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 )
@@ -102,7 +101,7 @@ func (g *Game) updateFireIntensityPerPixel(currentPixelIndex int) {
 		return
 	}
 
-	d := rand.Intn(3)
+	d := rand.IntN(3)
 	newI := int(g.indices[below]) - d
 	if newI < 0 {
 		newI = 0
@@ -139,8 +138,6 @@ func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
 }
 
 func main() {
-	rand.Seed(time.Now().UnixNano())
-
 	ebiten.SetWindowSize(screenWidth*6, screenHeight*6)
 	ebiten.SetWindowTitle("Doom Fire (Ebitengine Demo)")
 	if err := ebiten.RunGame(NewGame()); err != nil {
diff --git a/examples/drag/main.go b/examples/drag/main.go
index 8af91c3ef..e2475e88c 100644
--- a/examples/drag/main.go
+++ b/examples/drag/main.go
@@ -20,8 +20,7 @@ import (
 	"image/color"
 	_ "image/png"
 	"log"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
@@ -29,10 +28,6 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/inpututil"
 )
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 const (
 	screenWidth  = 640
 	screenHeight = 480
@@ -196,8 +191,8 @@ func NewGame() *Game {
 		s := &Sprite{
 			image:      ebitenImage,
 			alphaImage: ebitenAlphaImage,
-			x:          rand.Intn(screenWidth - w),
-			y:          rand.Intn(screenHeight - h),
+			x:          rand.IntN(screenWidth - w),
+			y:          rand.IntN(screenHeight - h),
 		}
 		sprites = append(sprites, s)
 	}
diff --git a/examples/flappy/main.go b/examples/flappy/main.go
index 186ea2002..7ca80406a 100644
--- a/examples/flappy/main.go
+++ b/examples/flappy/main.go
@@ -24,8 +24,7 @@ import (
 	_ "image/png"
 	"log"
 	"math"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/audio"
@@ -44,10 +43,6 @@ var flagCRT = flag.Bool("crt", false, "enable the CRT effect")
 //go:embed crt.go
 var crtGo []byte
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 func floorDiv(x, y int) int {
 	d := x / y
 	if d*y == x || x >= 0 {
@@ -150,7 +145,7 @@ func (g *Game) init() {
 	g.cameraY = 0
 	g.pipeTileYs = make([]int, 256)
 	for i := range g.pipeTileYs {
-		g.pipeTileYs[i] = rand.Intn(6) + 2
+		g.pipeTileYs[i] = rand.IntN(6) + 2
 	}
 
 	if g.audioContext == nil {
diff --git a/examples/font/main.go b/examples/font/main.go
index 1048c40ac..374447466 100644
--- a/examples/font/main.go
+++ b/examples/font/main.go
@@ -19,8 +19,7 @@ import (
 	"fmt"
 	"image/color"
 	"log"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/examples/resources/fonts"
@@ -94,10 +93,6 @@ func init() {
 	mplusFaceSource = s
 }
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 type Game struct {
 	counter        int
 	kanjiText      string
@@ -110,14 +105,14 @@ func (g *Game) Update() error {
 		g.kanjiText = ""
 		for j := 0; j < 6; j++ {
 			for i := 0; i < 12; i++ {
-				g.kanjiText += string(jaKanjis[rand.Intn(len(jaKanjis))])
+				g.kanjiText += string(jaKanjis[rand.IntN(len(jaKanjis))])
 			}
 			g.kanjiText += "\n"
 		}
 
-		g.kanjiTextColor.R = 0x80 + uint8(rand.Intn(0x7f))
-		g.kanjiTextColor.G = 0x80 + uint8(rand.Intn(0x7f))
-		g.kanjiTextColor.B = 0x80 + uint8(rand.Intn(0x7f))
+		g.kanjiTextColor.R = 0x80 + uint8(rand.IntN(0x7f))
+		g.kanjiTextColor.G = 0x80 + uint8(rand.IntN(0x7f))
+		g.kanjiTextColor.B = 0x80 + uint8(rand.IntN(0x7f))
 		g.kanjiTextColor.A = 0xff
 	}
 	g.counter++
diff --git a/examples/isometric/level.go b/examples/isometric/level.go
index 1f0539af4..56fd32ea6 100644
--- a/examples/isometric/level.go
+++ b/examples/isometric/level.go
@@ -16,8 +16,7 @@ package main
 
 import (
 	"fmt"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 )
 
 // Level represents a Game level.
@@ -56,9 +55,6 @@ func NewLevel() (*Level, error) {
 		return nil, fmt.Errorf("failed to load embedded spritesheet: %s", err)
 	}
 
-	// Generate a unique permutation each time.
-	r := rand.New(rand.NewSource(time.Now().UTC().UnixNano()))
-
 	// Fill each tile with one or more sprites randomly.
 	l.tiles = make([][]*Tile, l.h)
 	for y := 0; y < l.h; y++ {
@@ -66,7 +62,7 @@ func NewLevel() (*Level, error) {
 		for x := 0; x < l.w; x++ {
 			t := &Tile{}
 			isBorderSpace := x == 0 || y == 0 || x == l.w-1 || y == l.h-1
-			val := r.Intn(1000)
+			val := rand.IntN(1000)
 			switch {
 			case isBorderSpace || val < 275:
 				t.AddSprite(ss.Wall)
diff --git a/examples/life/main.go b/examples/life/main.go
index dfa773973..bdc94de35 100644
--- a/examples/life/main.go
+++ b/examples/life/main.go
@@ -8,16 +8,11 @@ package main
 
 import (
 	"log"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 )
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 // World represents the game state.
 type World struct {
 	area   []bool
@@ -39,8 +34,8 @@ func NewWorld(width, height int, maxInitLiveCells int) *World {
 // init inits world with a random state.
 func (w *World) init(maxLiveCells int) {
 	for i := 0; i < maxLiveCells; i++ {
-		x := rand.Intn(w.width)
-		y := rand.Intn(w.height)
+		x := rand.IntN(w.width)
+		y := rand.IntN(w.height)
 		w.area[y*w.width+x] = true
 	}
 }
diff --git a/examples/mascot/main.go b/examples/mascot/main.go
index a9efaeab1..5c51cf984 100644
--- a/examples/mascot/main.go
+++ b/examples/mascot/main.go
@@ -21,8 +21,7 @@ import (
 	"image"
 	_ "image/png"
 	"log"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	rmascot "github.com/hajimehoshi/ebiten/v2/examples/resources/images/mascot"
@@ -60,10 +59,6 @@ func init() {
 	gopher3 = ebiten.NewImageFromImage(img3)
 }
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 type mascot struct {
 	x16  int
 	y16  int
@@ -105,8 +100,8 @@ func (m *mascot) Update() error {
 	}
 
 	// If the mascto is on the ground, cause an action in random.
-	if rand.Intn(60) == 0 && m.y16 == 0 {
-		switch rand.Intn(2) {
+	if rand.IntN(60) == 0 && m.y16 == 0 {
+		switch rand.IntN(2) {
 		case 0:
 			// Jump.
 			m.vy16 = -240
diff --git a/examples/particles/main.go b/examples/particles/main.go
index b1b44b71b..081740fbf 100644
--- a/examples/particles/main.go
+++ b/examples/particles/main.go
@@ -23,18 +23,13 @@ import (
 	_ "image/png"
 	"log"
 	"math"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
 	"github.com/hajimehoshi/ebiten/v2/examples/resources/images"
 )
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 const (
 	screenWidth  = 640
 	screenHeight = 480
@@ -110,7 +105,7 @@ func (s *sprite) draw(screen *ebiten.Image) {
 }
 
 func newSprite(img *ebiten.Image) *sprite {
-	c := rand.Intn(50) + 300
+	c := rand.IntN(50) + 300
 	dir := rand.Float64() * 2 * math.Pi
 	a := rand.Float64() * 2 * math.Pi
 	s := rand.Float64()*0.1 + 0.4
@@ -136,7 +131,7 @@ func (g *Game) Update() error {
 		g.sprites = list.New()
 	}
 
-	if g.sprites.Len() < 500 && rand.Intn(4) < 3 {
+	if g.sprites.Len() < 500 && rand.IntN(4) < 3 {
 		// Emit
 		g.sprites.PushBack(newSprite(smokeImage))
 	}
diff --git a/examples/set/main.go b/examples/set/main.go
index bb00c50d7..1b9f8d4b8 100644
--- a/examples/set/main.go
+++ b/examples/set/main.go
@@ -18,8 +18,7 @@ import (
 	"fmt"
 	"image/color"
 	"log"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
@@ -30,10 +29,6 @@ const (
 	screenHeight = 240
 )
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 type Game struct {
 	offscreen *ebiten.Image
 }
@@ -46,12 +41,12 @@ func NewGame() *Game {
 
 func (g *Game) Update() error {
 	s := g.offscreen.Bounds().Size()
-	x := rand.Intn(s.X)
-	y := rand.Intn(s.Y)
+	x := rand.IntN(s.X)
+	y := rand.IntN(s.Y)
 	c := color.RGBA{
-		byte(rand.Intn(256)),
-		byte(rand.Intn(256)),
-		byte(rand.Intn(256)),
+		byte(rand.IntN(256)),
+		byte(rand.IntN(256)),
+		byte(rand.IntN(256)),
 		byte(0xff),
 	}
 	g.offscreen.Set(x, y, c)
diff --git a/examples/snake/main.go b/examples/snake/main.go
index b8b600f15..34dd9989b 100644
--- a/examples/snake/main.go
+++ b/examples/snake/main.go
@@ -18,8 +18,7 @@ import (
 	"fmt"
 	"image/color"
 	"log"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
@@ -59,10 +58,6 @@ type Game struct {
 	level         int
 }
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 func (g *Game) collidesWithApple() bool {
 	return g.snakeBody[0].X == g.apple.X &&
 		g.snakeBody[0].Y == g.apple.Y
@@ -130,8 +125,8 @@ func (g *Game) Update() error {
 		}
 
 		if g.collidesWithApple() {
-			g.apple.X = rand.Intn(xGridCountInScreen - 1)
-			g.apple.Y = rand.Intn(yGridCountInScreen - 1)
+			g.apple.X = rand.IntN(xGridCountInScreen - 1)
+			g.apple.Y = rand.IntN(yGridCountInScreen - 1)
 			g.snakeBody = append(g.snakeBody, Position{
 				X: g.snakeBody[len(g.snakeBody)-1].X,
 				Y: g.snakeBody[len(g.snakeBody)-1].Y,
diff --git a/examples/sprites/main.go b/examples/sprites/main.go
index 16afb0da6..aa4f5f510 100644
--- a/examples/sprites/main.go
+++ b/examples/sprites/main.go
@@ -21,7 +21,7 @@ import (
 	_ "image/png"
 	"log"
 	"math"
-	"math/rand"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
@@ -119,9 +119,9 @@ func (g *Game) init() {
 	g.sprites.num = 500
 	for i := range g.sprites.sprites {
 		w, h := ebitenImage.Bounds().Dx(), ebitenImage.Bounds().Dy()
-		x, y := rand.Intn(screenWidth-w), rand.Intn(screenHeight-h)
-		vx, vy := 2*rand.Intn(2)-1, 2*rand.Intn(2)-1
-		a := rand.Intn(maxAngle)
+		x, y := rand.IntN(screenWidth-w), rand.IntN(screenHeight-h)
+		vx, vy := 2*rand.IntN(2)-1, 2*rand.IntN(2)-1
+		a := rand.IntN(maxAngle)
 		g.sprites.sprites[i] = &Sprite{
 			imageWidth:  w,
 			imageHeight: h,
diff --git a/examples/spriteshd/main.go b/examples/spriteshd/main.go
index 4d6dd5635..6d6e8c7f0 100644
--- a/examples/spriteshd/main.go
+++ b/examples/spriteshd/main.go
@@ -21,7 +21,7 @@ import (
 	_ "image/png"
 	"log"
 	"math"
-	"math/rand"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
@@ -117,9 +117,9 @@ func (g *Game) init() {
 	g.sprites.num = 500
 	for i := range g.sprites.sprites {
 		w, h := ebitenImage.Bounds().Dx(), ebitenImage.Bounds().Dy()
-		x, y := rand.Intn(screenWidth-w), rand.Intn(screenHeight-h)
-		vx, vy := 2*rand.Intn(2)-1, 2*rand.Intn(2)-1
-		a := rand.Intn(maxAngle)
+		x, y := rand.IntN(screenWidth-w), rand.IntN(screenHeight-h)
+		vx, vy := 2*rand.IntN(2)-1, 2*rand.IntN(2)-1
+		a := rand.IntN(maxAngle)
 		g.sprites.sprites[i] = &Sprite{
 			imageWidth:  w,
 			imageHeight: h,
diff --git a/examples/squiral/main.go b/examples/squiral/main.go
index 3c5bc83be..5bcdf0d54 100644
--- a/examples/squiral/main.go
+++ b/examples/squiral/main.go
@@ -20,8 +20,7 @@ import (
 	"fmt"
 	"image/color"
 	"log"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
@@ -127,8 +126,8 @@ type squiral struct {
 func (s *squiral) spawn(game *Game) {
 	s.dead = false
 
-	rx := rand.Intn(width-4) + 2
-	ry := rand.Intn(height-4) + 2
+	rx := rand.IntN(width-4) + 2
+	ry := rand.IntN(height-4) + 2
 
 	for dx := -2; dx <= 2; dx++ {
 		for dy := -2; dy <= 2; dy++ {
@@ -140,15 +139,15 @@ func (s *squiral) spawn(game *Game) {
 		}
 	}
 
-	s.speed = rand.Intn(5) + 1
+	s.speed = rand.IntN(5) + 1
 	s.pos.x = rx
 	s.pos.y = ry
-	s.dir = rand.Intn(4)
+	s.dir = rand.IntN(4)
 
 	game.colorCycle = (game.colorCycle + 1) % len(palettes[game.selectedPalette].colors)
 	s.col = palettes[game.selectedPalette].colors[game.colorCycle]
 
-	s.rot = rand.Intn(2)
+	s.rot = rand.IntN(2)
 }
 
 func (s *squiral) step(game *Game) {
@@ -157,7 +156,7 @@ func (s *squiral) step(game *Game) {
 	}
 	x, y := s.pos.x, s.pos.y // shorthands
 
-	change := rand.Intn(1000)
+	change := rand.IntN(1000)
 	if change < 2 {
 		// On 0.2% of iterations, switch rotation direction.
 		s.rot = (s.rot + 1) % 2
@@ -267,10 +266,6 @@ func (a *automaton) step(game *Game) {
 	}
 }
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 type Game struct {
 	selectedPalette int
 	colorCycle      int
diff --git a/examples/stars/main.go b/examples/stars/main.go
index 9b79921d6..1f611e37b 100644
--- a/examples/stars/main.go
+++ b/examples/stars/main.go
@@ -17,8 +17,7 @@ package main
 import (
 	"image/color"
 	"log"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/vector"
@@ -97,7 +96,6 @@ func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
 }
 
 func main() {
-	rand.Seed(time.Now().UnixNano())
 	ebiten.SetWindowSize(screenWidth, screenHeight)
 	ebiten.SetWindowTitle("Stars (Ebitengine Demo)")
 	if err := ebiten.RunGame(NewGame()); err != nil {
diff --git a/examples/windowsize/main.go b/examples/windowsize/main.go
index 8722a6e7e..6e7d852e5 100644
--- a/examples/windowsize/main.go
+++ b/examples/windowsize/main.go
@@ -22,12 +22,11 @@ import (
 	_ "image/jpeg"
 	"log"
 	"math"
-	"math/rand"
+	"math/rand/v2"
 	"regexp"
 	"strconv"
 	"strings"
 	"sync"
-	"time"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
@@ -55,7 +54,6 @@ var (
 
 func init() {
 	flag.Parse()
-	rand.Seed(time.Now().UnixNano())
 }
 
 const (
@@ -71,9 +69,9 @@ var (
 func createRandomIconImage() image.Image {
 	const size = 32
 
-	rf := float64(rand.Intn(0x100))
-	gf := float64(rand.Intn(0x100))
-	bf := float64(rand.Intn(0x100))
+	rf := float64(rand.IntN(0x100))
+	gf := float64(rand.IntN(0x100))
+	bf := float64(rand.IntN(0x100))
 	img := ebiten.NewImage(size, size)
 	pix := make([]byte, 4*size*size)
 	for j := 0; j < size; j++ {
diff --git a/image_test.go b/image_test.go
index fc12afc6b..5eec9a5f2 100644
--- a/image_test.go
+++ b/image_test.go
@@ -22,10 +22,9 @@ import (
 	"image/draw"
 	_ "image/png"
 	"math"
-	"math/rand"
+	"math/rand/v2"
 	"runtime"
 	"testing"
-	"time"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/examples/resources/images"
@@ -37,10 +36,6 @@ import (
 // maxImageSize is a maximum image size that should work in almost every environment.
 const maxImageSize = 4096 - 2
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 func skipTooSlowTests(t *testing.T) bool {
 	if testing.Short() {
 		t.Skip("skipping test in short mode")
@@ -4272,7 +4267,7 @@ func TestImageAntiAlias(t *testing.T) {
 		ebiten.BlendXor,
 		ebiten.BlendLighter,
 	} {
-		rnd := rand.New(rand.NewSource(0))
+		rnd := rand.New(rand.NewPCG(0, 0))
 		max := func(x, y, z byte) byte {
 			if x >= y && x >= z {
 				return x
diff --git a/internal/affine/colorm_test.go b/internal/affine/colorm_test.go
index 1f30867c2..9257f0769 100644
--- a/internal/affine/colorm_test.go
+++ b/internal/affine/colorm_test.go
@@ -16,7 +16,7 @@ package affine_test
 
 import (
 	"math"
-	"math/rand"
+	"math/rand/v2"
 	"testing"
 
 	"github.com/hajimehoshi/ebiten/v2/internal/affine"