mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-11-15 07:27:32 +01:00
146 lines
3.2 KiB
Go
146 lines
3.2 KiB
Go
// Copyright 2022 The Ebiten Authors
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package main
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import (
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"log"
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"math"
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"sync"
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"time"
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"github.com/hajimehoshi/ebiten/v2"
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"github.com/hajimehoshi/ebiten/v2/audio"
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"github.com/hajimehoshi/ebiten/v2/ebitenutil"
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)
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const (
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screenWidth = 640
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screenHeight = 480
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sampleRate = 48000
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)
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type Game struct {
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audioContext *audio.Context
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player *audio.Player
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sineWave *SineWave
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}
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type SineWave struct {
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frequency int
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minFrequency int
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maxFrequency int
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// pos is the position in the wave length in the range of [0, 1).
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pos float64
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m sync.Mutex
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}
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func NewSineWave() *SineWave {
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return &SineWave{
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frequency: 440,
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minFrequency: 440,
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maxFrequency: 880,
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}
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}
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func (s *SineWave) Update(raisePitch bool) {
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s.m.Lock()
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defer s.m.Unlock()
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if raisePitch {
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if s.frequency < s.maxFrequency {
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s.frequency += 10
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}
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} else {
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if s.frequency > s.minFrequency {
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s.frequency -= 10
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}
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}
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}
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func (s *SineWave) Read(buf []byte) (int, error) {
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s.m.Lock()
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defer s.m.Unlock()
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const bytesPerSample = 8
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n := len(buf) / bytesPerSample * bytesPerSample
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buf = buf[:n]
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length := sampleRate / float64(s.frequency)
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p := float64(length * s.pos)
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for i := 0; i < n/bytesPerSample; i++ {
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v := math.Float32bits(float32(math.Sin(2 * math.Pi * p / length)))
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buf[8*i] = byte(v)
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buf[8*i+1] = byte(v >> 8)
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buf[8*i+2] = byte(v >> 16)
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buf[8*i+3] = byte(v >> 24)
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buf[8*i+4] = byte(v)
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buf[8*i+5] = byte(v >> 8)
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buf[8*i+6] = byte(v >> 16)
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buf[8*i+7] = byte(v >> 24)
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p++
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}
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_, s.pos = math.Modf(p / length)
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return n, nil
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}
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func NewGame() *Game {
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return &Game{
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audioContext: audio.NewContext(sampleRate),
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}
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}
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func (g *Game) Update() error {
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if g.audioContext == nil {
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g.audioContext = audio.NewContext(sampleRate)
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}
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if g.player == nil {
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g.sineWave = NewSineWave()
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p, err := g.audioContext.NewPlayerF32(g.sineWave)
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if err != nil {
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return err
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}
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g.player = p
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g.player.Play()
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// Adjust the buffer size to reflect the audio source changes in real time.
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// Note that Ebitengine doesn't guarantee the audio quality when the buffer size is modified.
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// 1/20[s] should work in most cases, but this might cause glitches in some environments.
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g.player.SetBufferSize(time.Second / 20)
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}
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g.sineWave.Update(ebiten.IsKeyPressed(ebiten.KeyA))
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return nil
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}
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func (g *Game) Draw(screen *ebiten.Image) {
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ebitenutil.DebugPrint(screen, "This is an example of a real time PCM.\nPress and hold the A key.")
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}
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func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
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return screenWidth, screenHeight
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}
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func main() {
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ebiten.SetWindowSize(screenWidth, screenHeight)
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ebiten.SetWindowTitle("Real Time PCM (Ebitengine Demo)")
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if err := ebiten.RunGame(NewGame()); err != nil {
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log.Fatal(err)
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}
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}
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