mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-27 04:08:53 +01:00
145 lines
2.9 KiB
Go
145 lines
2.9 KiB
Go
// Copyright 2015 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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"bytes"
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"fmt"
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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/ebitenutil"
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"github.com/hajimehoshi/ebiten/exp/audio"
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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 frames = 0
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const (
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freqA = 440.0
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freqAS = 466.2
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freqB = 493.9
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freqC = 523.3
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freqCS = 554.4
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freqD = 587.3
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freqDS = 622.3
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freqE = 659.3
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freqF = 698.5
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freqFS = 740.0
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freqG = 784.0
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freqGS = 830.6
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)
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const score = `CCGGAAGR FFEEDDCR GGFFEEDR GGFFEEDR CCGGAAGR FFEEDDCR`
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var scoreIndex = 0
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func square(out []int16, volume float64, freq float64, sequence float64) {
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if freq == 0 {
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for i := 0; i < len(out); i++ {
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out[i] = 0
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}
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return
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}
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length := int(float64(sampleRate) / freq)
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if length == 0 {
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panic("invalid freq")
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}
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for i := 0; i < len(out); i++ {
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a := int16(volume * math.MaxInt16)
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if i%length < int(float64(length)*sequence) {
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a = -a
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}
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out[i] = a
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}
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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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return nil
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}
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func addNote() {
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size := sampleRate / 60
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notes := []float64{freqC, freqD, freqE, freqF, freqG, freqA * 2, freqB * 2}
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defer func() {
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scoreIndex++
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scoreIndex %= len(score)
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}()
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l := make([]int16, size*30)
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r := make([]int16, size*30)
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note := score[scoreIndex]
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for note == ' ' {
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scoreIndex++
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scoreIndex %= len(score)
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note = score[scoreIndex]
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}
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freq := 0.0
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switch {
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case note == 'R':
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freq = 0
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case note <= 'B':
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freq = notes[int(note)+len(notes)-int('C')]
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default:
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freq = notes[note-'C']
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}
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vol := 1.0 / 16.0
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square(l, vol, freq, 0.25)
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square(r, vol, freq, 0.25)
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b := toBytes(l, r)
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p := audio.NewPlayer(&stream{bytes.NewReader(b)}, sampleRate)
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p.Play()
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}
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func update(screen *ebiten.Image) error {
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defer func() {
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frames++
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}()
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if frames%30 == 0 {
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addNote()
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}
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ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %0.2f", ebiten.CurrentFPS()))
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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, "Audio (Ebiten Demo)"); err != nil {
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log.Fatal(err)
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}
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}
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