mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-09-20 05:12:18 +02:00
109 lines
2.6 KiB
Go
109 lines
2.6 KiB
Go
// Copyright 2016 Hajime Hoshi
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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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"fmt"
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"log"
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"math"
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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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frequency = 440
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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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pos 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(buf []byte) (int, error) {
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const bytesPerSample = 8
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n := len(buf) / bytesPerSample * bytesPerSample
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const length = sampleRate / frequency
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for i := 0; i < n/bytesPerSample; i++ {
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v := math.Float32bits(float32(math.Sin(2 * math.Pi * float64(s.pos/bytesPerSample+int64(i)) / 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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}
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s.pos += int64(n)
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s.pos %= length * bytesPerSample
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return n, 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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type Game struct {
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audioContext *audio.Context
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player *audio.Player
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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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// Pass the (infinite) stream to 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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g.player, err = g.audioContext.NewPlayerF32(&stream{})
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if err != nil {
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return err
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}
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g.player.Play()
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}
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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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msg := fmt.Sprintf("TPS: %0.2f\nThis is an example using infinite audio stream.", ebiten.ActualTPS())
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ebitenutil.DebugPrint(screen, msg)
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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("Sine Wave (Ebitengine Demo)")
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if err := ebiten.RunGame(&Game{}); err != nil {
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log.Fatal(err)
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}
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}
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