Add FPS const

ebitenutil/gif.go

@@ -50,8 +50,7 @@ func init() {
 }
 
 func (r *recorder) delay() int {
-	// Assume that the FPS is 60.
-	delay := 100 * r.skips / 60
+	delay := 100 * r.skips / ebiten.FPS
 	if delay < 2 {
 		return 2
 	}

examples/alphablending/main.go

@@ -36,7 +36,7 @@ var (
 
 func update(screen *ebiten.Image) error {
 	count++
-	count %= 600
+	count %= ebiten.FPS * 10
 	diff := float64(count) * 0.2
 	switch {
 	case 480 < count:

examples/blocks/blocks/gamepadscene.go

@@ -69,7 +69,7 @@ func (s *GamepadScene) Update(state *GameState) error {
 	if state.Input.gamepadConfig.Scan(0, b) {
 		s.currentIndex++
 		if s.currentIndex == len(gamepadStdButtons) {
-			s.countAfterSetting = 60
+			s.countAfterSetting = ebiten.FPS
 		}
 	}
 	return nil

examples/blocks/blocks/gamescene.go

@@ -260,7 +260,7 @@ func (s *GameScene) Update(state *GameState) error {
 
 	s.currentFrame++
 
-	const maxLandingCount = 60
+	const maxLandingCount = ebiten.FPS
 	if s.currentPiece == nil {
 		s.initCurrentPiece(s.choosePiece())
 	}
@@ -303,8 +303,9 @@ func (s *GameScene) Update(state *GameState) error {
 		y := s.currentPieceY
 		angle := s.currentPieceAngle
 		s.currentPieceYCarry += 2*s.level() + 1
-		for 60 <= s.currentPieceYCarry {
-			s.currentPieceYCarry -= 60
+		const maxCarry = 60
+		for maxCarry <= s.currentPieceYCarry {
+			s.currentPieceYCarry -= maxCarry
 			s.currentPieceY = s.field.DropPiece(piece, s.currentPieceX, s.currentPieceY, angle)
 			moved = y != s.currentPieceY
 		}

examples/paint/main.go

@@ -47,7 +47,7 @@ func update(screen *ebiten.Image) error {
 		op := &ebiten.DrawImageOptions{}
 		op.GeoM.Translate(float64(mx), float64(my))
 		op.ColorM.Scale(1.0, 0.50, 0.125, 1.0)
-		theta := 2.0 * math.Pi * float64(count%60) / 60.0
+		theta := 2.0 * math.Pi * float64(count%60) / ebiten.FPS
 		op.ColorM.RotateHue(theta)
 		if err := canvasImage.DrawImage(brushImage, op); err != nil {
 			return err

examples/pcm/main.go

@@ -94,7 +94,7 @@ func toBytes(l, r []int16) []byte {
 }
 
 func addNote() error {
-	size := sampleRate / 60
+	size := sampleRate / ebiten.FPS
 	notes := []float64{freqC, freqD, freqE, freqF, freqG, freqA * 2, freqB * 2}
 
 	defer func() {

exp/audio/audio.go

@@ -19,6 +19,8 @@ import (
 	"io"
 	"sync"
 	"time"
+
+	"github.com/hajimehoshi/ebiten"
 )
 
 type mixedPlayersStream struct {
@@ -43,8 +45,7 @@ func (s *mixedPlayersStream) Read(b []byte) (int, error) {
 	s.context.Lock()
 	defer s.context.Unlock()
 
-	// TODO: 60 (FPS) is a magic number
-	bytesPerFrame := s.context.sampleRate * bytesPerSample * channelNum / 60
+	bytesPerFrame := s.context.sampleRate * bytesPerSample * channelNum / ebiten.FPS
 	x := s.context.frames*bytesPerFrame + len(b)
 	if x <= s.writtenBytes {
 		return 0, nil

exp/audio/audio_js.go

@@ -21,6 +21,7 @@ import (
 	"runtime"
 
 	"github.com/gopherjs/gopherjs/js"
+	"github.com/hajimehoshi/ebiten"
 )
 
 type player struct {
@@ -75,7 +76,7 @@ func max64(a, b int64) int64 {
 }
 
 func (p *player) proceed() error {
-	bufferSize := p.sampleRate * bytesPerSample * channelNum / 60
+	bufferSize := p.sampleRate * bytesPerSample * channelNum / ebiten.FPS
 	c := int64(p.context.Get("currentTime").Float() * float64(p.sampleRate))
 	if p.positionInSamples < c {
 		p.positionInSamples = c

internal/ui/ui_glfw.go

@@ -154,6 +154,7 @@ func (u *userInterface) doEvents() error {
 		return err
 	}
 	for u.window.GetAttrib(glfw.Focused) == 0 {
+		// Wait for an arbitrary period to avoid busy loop.
 		time.Sleep(time.Second / 60)
 		if err := u.pollEvents(); err != nil {
 			return err

run.go

@@ -29,12 +29,20 @@ var runContext = &struct {
 	isRunningSlowly bool
 }{}
 
-// CurrentFPS returns the current number of frames per second.
+// FPS represents how many times game updating happens in a second.
+const FPS = 60
+
+// CurrentFPS returns the current number of frames per second of rendering.
+//
+// This value represents how many times rendering happens in 1/60 second and
+// NOT how many times logical game updating (a passed function to Run) happens.
+// Note that logical game updating is assured to happen 60 times in a second
+// as long as the screen is active.
 func CurrentFPS() float64 {
 	return runContext.fps
 }
 
-// IsRunningSlowly returns true if the game is running too slowly to keep 60 FPS.
+// IsRunningSlowly returns true if the game is running too slowly to keep 60 FPS of rendering.
 // The game screen is not updated when IsRunningSlowly is true.
 // It is recommended to skip heavy processing, especially drawing, when IsRunningSlowly is true.
 func IsRunningSlowly() bool {
@@ -103,10 +111,10 @@ func Run(f func(*Image) error, width, height, scale int, title string) error {
 		now := ui.Now()
 		// If beforeForUpdate is too old, we assume that screen is not shown.
 		runContext.isRunningSlowly = false
-		if int64(5*time.Second/60) < now-beforeForUpdate {
+		if int64(5*time.Second/FPS) < now-beforeForUpdate {
 			beforeForUpdate = now
 		} else {
-			c := float64(now-beforeForUpdate) * 60 / float64(time.Second)
+			c := float64(now-beforeForUpdate) * FPS / float64(time.Second)
 			runContext.isRunningSlowly = c >= 2.5
 			for i := 0; i < int(c); i++ {
 				if err := ui.DoEvents(); err != nil {
@@ -119,7 +127,7 @@ func Run(f func(*Image) error, width, height, scale int, title string) error {
 					return err
 				}
 			}
-			beforeForUpdate += int64(c) * int64(time.Second/60)
+			beforeForUpdate += int64(c) * int64(time.Second/FPS)
 			ui.SwapBuffers()
 		}