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examples/piano: Refactoring
This commit is contained in:
Hajime Hoshi
parent
531e661f0b
commit
6e5830739f
@ -32,10 +32,6 @@ import (
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"github.com/hajimehoshi/ebiten/text"
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)
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const (
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arcadeFontSize = 8
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)
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var (
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arcadeFont font.Face
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)
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@ -57,7 +53,10 @@ func init() {
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log.Fatal(err)
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}
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const dpi = 72
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const (
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arcadeFontSize = 8
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dpi = 72
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)
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arcadeFont = truetype.NewFace(tt, &truetype.Options{
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Size: arcadeFontSize,
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DPI: dpi,
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@ -69,6 +68,7 @@ const (
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screenWidth = 320
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screenHeight = 240
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sampleRate = 44100
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baseFreq = 220
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)
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var audioContext *audio.Context
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@ -81,27 +81,21 @@ func init() {
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}
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}
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var pcm = make([]float64, 4*sampleRate)
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const baseFreq = 220
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func init() {
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// pianoAt returns an i-th sample of piano with the given frequency.
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func pianoAt(i int, freq float64) float64 {
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// Create piano-like waves with multiple sin waves.
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amp := []float64{1.0, 0.8, 0.6, 0.4, 0.2}
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x := []float64{4.0, 2.0, 1.0, 0.5, 0.25}
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for i := 0; i < len(pcm); i++ {
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v := 0.0
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for j := 0; j < len(amp); j++ {
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a := amp[j] * math.Exp(-5*float64(i)/(x[j]*sampleRate))
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v += a * math.Sin(2.0*math.Pi*float64(i)*baseFreq*float64(j+1)/sampleRate)
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}
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pcm[i] = v / 5.0
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// Decay
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a := amp[j] * math.Exp(-5*float64(i)*freq/baseFreq/(x[j]*sampleRate))
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v += a * math.Sin(2.0*math.Pi*float64(i)*freq*float64(j+1)/sampleRate)
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}
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return v / 5.0
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}
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var (
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noteCache = map[int][]byte{}
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)
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// toBytes returns the 2ch little endian 16bit byte sequence with the given left/right sequence.
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func toBytes(l, r []int16) []byte {
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if len(l) != len(r) {
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panic("len(l) must equal to len(r)")
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@ -116,36 +110,88 @@ func toBytes(l, r []int16) []byte {
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return b
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}
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func addNote(freq float64, vol float64) {
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// TODO: Call Close method of *audio.Player.
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// However, this works without Close because Close is automatically called when GC
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// collects a *audio.Player object.
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f := int(freq)
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if n, ok := noteCache[f]; ok {
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p, _ := audio.NewPlayerFromBytes(audioContext, n)
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p.Play()
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return
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var (
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pianoNoteSamples = map[int][]byte{}
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pianoNoteSamplesInited = false
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pianoNoteSamplesInitCh = make(chan struct{})
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)
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func init() {
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// Initialize piano data.
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// This takes a little long time (especially on browsers),
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// so run this asynchronously and notice the progress.
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go func() {
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// Create a reference data and use this for other frequency.
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const refFreq = 110
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length := 4 * sampleRate * baseFreq / refFreq
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refData := make([]int16, length)
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for i := 0; i < length; i++ {
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refData[i] = int16(pianoAt(i, refFreq) * math.MaxInt16)
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}
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length := len(pcm) * baseFreq / f
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for i := range keys {
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freq := baseFreq * math.Exp2(float64(i-1)/12.0)
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// Clculate the wave data for the freq.
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length := 4 * sampleRate * baseFreq / int(freq)
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l := make([]int16, length)
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r := make([]int16, length)
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j := 0
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jj := 0
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for i := 0; i < len(l); i++ {
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p := pcm[j]
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l[i] = int16(p * vol * math.MaxInt16)
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r[i] = l[i]
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jj += f
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j = jj / baseFreq
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for i := 0; i < length; i++ {
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idx := int(float64(i) * freq / refFreq)
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if len(refData) <= idx {
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break
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}
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l[i] = refData[idx]
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}
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copy(r, l)
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n := toBytes(l, r)
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noteCache[f] = n
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p, _ := audio.NewPlayerFromBytes(audioContext, n)
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p.Play()
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return
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pianoNoteSamples[int(freq)] = n
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}
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close(pianoNoteSamplesInitCh)
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}()
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}
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var keys = []ebiten.Key{
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// playNote plays piano sound with the given frequency.
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func playNote(freq float64) {
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f := int(freq)
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p, _ := audio.NewPlayerFromBytes(audioContext, pianoNoteSamples[f])
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p.Play()
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}
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var (
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pianoImage *ebiten.Image
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)
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func init() {
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pianoImage, _ = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
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const (
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keyWidth = 24
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y = 48
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)
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whiteKeys := []string{"A", "S", "D", "F", "G", "H", "J", "K", "L"}
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for i, k := range whiteKeys {
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x := i*keyWidth + 36
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height := 112
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ebitenutil.DrawRect(pianoImage, float64(x), float64(y), float64(keyWidth-1), float64(height), color.White)
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text.Draw(pianoImage, k, arcadeFont, x+8, y+height-8, color.Black)
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}
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blackKeys := []string{"Q", "W", "", "R", "T", "", "U", "I", "O"}
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for i, k := range blackKeys {
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if k == "" {
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continue
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}
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x := i*keyWidth + 24
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height := 64
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ebitenutil.DrawRect(pianoImage, float64(x), float64(y), float64(keyWidth-1), float64(height), color.Black)
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text.Draw(pianoImage, k, arcadeFont, x+8, y+height-8, color.White)
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}
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}
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var (
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keys = []ebiten.Key{
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ebiten.KeyQ,
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ebiten.KeyA,
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ebiten.KeyW,
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@ -162,16 +208,11 @@ var keys = []ebiten.Key{
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ebiten.KeyK,
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ebiten.KeyO,
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ebiten.KeyL,
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}
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var keyStates = map[ebiten.Key]int{}
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func init() {
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for _, key := range keys {
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keyStates[key] = 0
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}
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}
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keyStates = map[ebiten.Key]int{}
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)
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// updateInput updates the input state.
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func updateInput() {
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for _, key := range keys {
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if !ebiten.IsKeyPressed(key) {
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@ -182,47 +223,33 @@ func updateInput() {
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}
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}
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var (
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imagePiano *ebiten.Image
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)
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func init() {
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imagePiano, _ = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
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whiteKeys := []string{"A", "S", "D", "F", "G", "H", "J", "K", "L"}
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width := 24
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y := 48
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for i, k := range whiteKeys {
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x := i*width + 36
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height := 112
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ebitenutil.DrawRect(imagePiano, float64(x), float64(y), float64(width-1), float64(height), color.White)
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text.Draw(imagePiano, k, arcadeFont, x+8, y+height-8, color.Black)
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}
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blackKeys := []string{"Q", "W", "", "R", "T", "", "U", "I", "O"}
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for i, k := range blackKeys {
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if k == "" {
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continue
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}
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x := i*width + 24
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height := 64
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ebitenutil.DrawRect(imagePiano, float64(x), float64(y), float64(width-1), float64(height), color.Black)
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text.Draw(imagePiano, k, arcadeFont, x+8, y+height-8, color.White)
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}
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}
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func update(screen *ebiten.Image) error {
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// The piano data is still being initialized.
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// Get the progress if available.
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if !pianoNoteSamplesInited {
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select {
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case <-pianoNoteSamplesInitCh:
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pianoNoteSamplesInited = true
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default:
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}
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}
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if pianoNoteSamplesInited {
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updateInput()
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for i, key := range keys {
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if keyStates[key] != 1 {
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continue
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}
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addNote(220*math.Exp2(float64(i-1)/12.0), 1.0)
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playNote(baseFreq * math.Exp2(float64(i-1)/12.0))
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}
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}
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if ebiten.IsRunningSlowly() {
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return nil
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}
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screen.Fill(color.RGBA{0x80, 0x80, 0xc0, 0xff})
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screen.DrawImage(imagePiano, nil)
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screen.DrawImage(pianoImage, nil)
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ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %0.2f", ebiten.CurrentFPS()))
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return nil
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