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151 lines
5.1 KiB
HTML
151 lines
5.1 KiB
HTML
<!DOCTYPE html>
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<meta charset="utf-8">
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<meta property="og:image" itemprop="image primaryImageOfPage" content="https://hajimehoshi.github.io/ebiten/images/examples/sinewave.png">
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<meta name="description" content="Ebiten example - sinewave">
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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 - sinewave</title>
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<link rel="stylesheet" href="../stylesheets/bootstrap.min.css">
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<link rel="stylesheet" href="../stylesheets/highlight-github.css">
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<link rel="stylesheet" href="../stylesheets/ebiten.css">
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<script src="../scripts/googleanalytics.js"></script>
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<nav class="navbar"><div class="container">
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<nav class="d-flex flex-row" style="width: 100%;">
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<div class="nav mr-auto"><a class="navbar-brand" href="../"><img src="../images/logo_white.svg" alt="EBITEN"></a></div>
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<ul class="nav">
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<li class="nav-item"><a class="nav-link" href="https://github.com/hajimehoshi/ebiten">GitHub</a></li>
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<li class="nav-item"><a class="nav-link" href="https://godoc.org/github.com/hajimehoshi/ebiten">GoDoc</a></li>
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<li class="nav-item"><a class="nav-link" href="https://github.com/hajimehoshi/ebiten/wiki">Wiki</a>
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<li class="nav-item"><a class="nav-link" href="https://ebiten-playground.github.io/">Playground</a>
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</ul>
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</nav>
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</div></nav>
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<main><div class="container">
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<h2>Ebiten example - sinewave</h2>
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<iframe src="sinewave.content.html" width="640" height="480"></iframe>
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<div class="card"><pre class="card-body"><code class="language-go">// +build example
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package main
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import (
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"errors"
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"fmt"
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"io"
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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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)
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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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frequency = 440
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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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// stream is an infinite stream of 440 Hz sine wave.
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type stream struct {
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position int64
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}
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// Read is io.Reader's Read.
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//
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// Read fills the data with sine wave samples.
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func (s *stream) Read(data []byte) (int, error) {
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if len(data)%4 != 0 {
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return 0, errors.New("len(data) % 4 must be 0")
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}
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const length = sampleRate / frequency // TODO: This should be integer?
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p := s.position / 4
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for i := 0; i < len(data)/4; i++ {
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const max = (1<<15 - 1) / 2
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b := int16(math.Sin(2*math.Pi*float64(p)/length) * max)
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data[4*i] = byte(b)
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data[4*i+1] = byte(b >> 8)
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data[4*i+2] = byte(b)
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data[4*i+3] = byte(b >> 8)
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p++
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}
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s.position += int64(len(data))
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s.position %= length * 4
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return len(data), nil
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}
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// Seek is io.Seeker's Seek.
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//
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// whence must be io.SeekStart or io.SeekCurrent.
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func (s *stream) Seek(offset int64, whence int) (int64, error) {
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const length = sampleRate / frequency
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switch whence {
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case io.SeekStart:
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s.position = offset
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case io.SeekCurrent:
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s.position += offset
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default:
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return 0, errors.New("whence must be io.SeekStart or io.SeekCurrent")
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}
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s.position %= length * 4
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return s.position, nil
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}
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// Close is io.Closer's Close.
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func (s *stream) Close() error {
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return nil
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}
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var player *audio.Player
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func update(screen *ebiten.Image) error {
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if player == nil {
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// Pass the (infinite) stream to audio.NewPlayer.
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// After calling Play, the stream never ends as long as the player object lives.
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var err error
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player, err = audio.NewPlayer(audioContext, &stream{})
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if err != nil {
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return err
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}
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player.Play()
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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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msg := fmt.Sprintf("FPS: %0.2f\nThis is an example using infinite audio stream.", ebiten.CurrentFPS())
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ebitenutil.DebugPrint(screen, msg)
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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, "Sine Wave (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></div>
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</div></main>
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<footer><div class="container">
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<p>© 2013 Hajime Hoshi</p>
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<p>Code is licensed under <a href="https://github.com/hajimehoshi/ebiten/blob/master/LICENSE">the Apache License 2.0</a>.</p>
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<p>The content of this page is licensed under <a href="https://creativecommons.org/licenses/by/4.0/">the Creative Commons Attribution 4.0 License</a>.</p>
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</div></footer>
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<script src="../scripts/highlight.pack.js"></script>
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<script>hljs.initHighlightingOnLoad();</script>
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