mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-11-10 13:07:26 +01:00
126 lines
2.5 KiB
Go
126 lines
2.5 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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"fmt"
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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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"log"
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"math"
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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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)
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var pcm = make([]float64, 4*audio.SampleRate())
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const baseFreq = 220
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func init() {
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s := float64(audio.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
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}
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}
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func addNote(freq float64, vol float64) {
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f := int(freq)
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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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if baseFreq <= freq {
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x := 0
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i := 0
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for _, p := range pcm {
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x += baseFreq
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x %= f
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if x < baseFreq {
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l[i] = int16(p * vol * math.MaxInt16)
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r[i] = l[i]
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i++
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}
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}
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} else {
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// Not implemented
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}
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audio.Play(-1, l, r)
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}
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var keys = []ebiten.Key{
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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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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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addNote(220*math.Exp2(float64(i)/12.0), 1.0/8.0)
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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, "Piano (Ebiten Demo)"); err != nil {
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log.Fatal(err)
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}
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}
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