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266 lines
6.6 KiB
HTML
266 lines
6.6 KiB
HTML
<!DOCTYPE html>
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<!--
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Copyright 2014 Hajime Hoshi
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<link rel="shortcut icon" href="../favicon.png" type="image/png" >
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<link rel="icon" href="../favicon.png" type="image/png" >
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<title>Ebiten example - piano</title>
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<style>
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body {
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font-family: sans-serif;
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}
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iframe {
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border-color: #999;
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border-style: solid;
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border-width: 1px;
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overflow: hidden;
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}
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pre {
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background: #eee;
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padding: 1em;
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}
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</style>
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<nav><a href="..">Ebiten</a></nav>
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<h1>Ebiten example - piano</h1>
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<iframe src="piano.content.html" width="640" height="480"></iframe>
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<pre><code>package main
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import (
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"bytes"
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"fmt"
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"image/color"
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"log"
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"math"
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"github.com/hajimehoshi/ebiten"
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"github.com/hajimehoshi/ebiten/audio"
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"github.com/hajimehoshi/ebiten/ebitenutil"
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"github.com/hajimehoshi/ebiten/examples/common"
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)
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const (
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screenWidth = 320
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screenHeight = 240
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sampleRate = 44100
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)
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var audioContext *audio.Context
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func init() {
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var err error
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audioContext, err = audio.NewContext(sampleRate)
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if err != nil {
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log.Fatal(err)
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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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s := float64(sampleRate)
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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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twoPiF := 2.0 * math.Pi * baseFreq
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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]*s))
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v += a * math.Sin(float64(i)*twoPiF*float64(j+1)/s)
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}
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pcm[i] = v / 5.0
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}
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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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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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}
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b := make([]byte, len(l)*4)
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for i, _ := range l {
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b[4*i] = byte(l[i])
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b[4*i+1] = byte(l[i] >> 8)
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b[4*i+2] = byte(r[i])
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b[4*i+3] = byte(r[i] >> 8)
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}
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return b
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}
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type stream struct {
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*bytes.Reader
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}
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func (s *stream) Close() error {
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s.Reader = nil
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return nil
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}
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func addNote(freq float64, vol float64) error {
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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, err := audio.NewPlayer(audioContext, &stream{bytes.NewReader(n)})
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if err != nil {
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return err
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}
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p.Play()
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return nil
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}
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length := len(pcm) * baseFreq / f
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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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}
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n := toBytes(l, r)
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noteCache[f] = n
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p, err := audio.NewPlayer(audioContext, &stream{bytes.NewReader(n)})
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if err != nil {
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return err
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}
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p.Play()
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return nil
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}
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var 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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ebiten.KeyS,
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ebiten.KeyD,
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ebiten.KeyR,
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ebiten.KeyF,
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ebiten.KeyT,
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ebiten.KeyG,
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ebiten.KeyH,
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ebiten.KeyU,
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ebiten.KeyJ,
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ebiten.KeyI,
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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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func updateInput() {
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for _, key := range keys {
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if !ebiten.IsKeyPressed(key) {
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keyStates[key] = 0
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continue
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}
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keyStates[key]++
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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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var err error
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imageEmpty, err := ebiten.NewImage(16, 16, ebiten.FilterNearest)
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if err != nil {
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panic(err)
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}
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imageEmpty.Fill(color.White)
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imagePiano, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
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if err != nil {
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panic(err)
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}
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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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op := &ebiten.DrawImageOptions{}
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w, h := imageEmpty.Size()
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op.GeoM.Scale(float64(width-1)/float64(w), float64(height)/float64(h))
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op.GeoM.Translate(float64(x), float64(y))
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op.ColorM.Scale(1, 1, 1, 1)
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imagePiano.DrawImage(imageEmpty, op)
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common.ArcadeFont.DrawText(imagePiano, k, x+8, y+height-16, 1, 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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op := &ebiten.DrawImageOptions{}
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w, h := imageEmpty.Size()
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op.GeoM.Scale(float64(width-1)/float64(w), float64(height)/float64(h))
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op.GeoM.Translate(float64(x), float64(y))
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op.ColorM.Scale(0, 0, 0, 1)
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imagePiano.DrawImage(imageEmpty, op)
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common.ArcadeFont.DrawText(imagePiano, k, x+8, y+height-16, 1, color.White)
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}
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}
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func update(screen *ebiten.Image) error {
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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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if err := addNote(220*math.Exp2(float64(i-1)/12.0), 1.0); err != nil {
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return err
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}
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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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ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %0.2f", ebiten.CurrentFPS()))
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if err := audioContext.Update(); err != nil {
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return err
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}
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return nil
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}
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func main() {
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if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Piano (Ebiten Demo)"); err != nil {
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log.Fatal(err)
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}
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}
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</code></pre>
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<footer>© 2014 Hajime Hoshi</footer>
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