ebiten/examples/piano/main.go
2016-02-11 03:07:14 +09:00

211 lines
4.5 KiB
Go

// Copyright 2015 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"bytes"
"fmt"
"image/color"
"log"
"math"
"github.com/hajimehoshi/ebiten"
"github.com/hajimehoshi/ebiten/ebitenutil"
"github.com/hajimehoshi/ebiten/examples/common"
"github.com/hajimehoshi/ebiten/exp/audio"
)
const (
screenWidth = 320
screenHeight = 240
sampleRate = 44100
)
var pcm = make([]float64, 4*sampleRate)
const baseFreq = 220
func init() {
s := float64(sampleRate)
amp := []float64{1.0, 0.8, 0.6, 0.4, 0.2}
x := []float64{4.0, 2.0, 1.0, 0.5, 0.25}
for i := 0; i < len(pcm); i++ {
v := 0.0
twoPiF := 2.0 * math.Pi * baseFreq
for j := 0; j < len(amp); j++ {
a := amp[j] * math.Exp(-5*float64(i)/(x[j]*s))
v += a * math.Sin(float64(i)*twoPiF*float64(j+1)/s)
}
pcm[i] = v / 5.0
}
}
var (
noteCache = map[int][]byte{}
)
func toBytes(l, r []int16) []byte {
if len(l) != len(r) {
panic("len(l) must equal to len(r)")
}
b := make([]byte, len(l)*4)
for i, _ := range l {
b[4*i] = byte(l[i])
b[4*i+1] = byte(l[i] >> 8)
b[4*i+2] = byte(r[i])
b[4*i+3] = byte(r[i] >> 8)
}
return b
}
type stream struct {
*bytes.Reader
}
func (s *stream) Close() error {
return nil
}
func addNote(freq float64, vol float64) {
f := int(freq)
if n, ok := noteCache[f]; ok {
p := audio.NewPlayer(&stream{bytes.NewReader(n)}, sampleRate)
p.Play()
return
}
length := len(pcm) * baseFreq / f
l := make([]int16, length)
r := make([]int16, length)
j := 0
jj := 0
for i := 0; i < len(l); i++ {
p := pcm[j]
l[i] = int16(p * vol * math.MaxInt16)
r[i] = l[i]
jj += f
j = jj / baseFreq
}
n := toBytes(l, r)
noteCache[f] = n
p := audio.NewPlayer(&stream{bytes.NewReader(n)}, sampleRate)
p.Play()
}
var keys = []ebiten.Key{
ebiten.KeyQ,
ebiten.KeyA,
ebiten.KeyW,
ebiten.KeyS,
ebiten.KeyD,
ebiten.KeyR,
ebiten.KeyF,
ebiten.KeyT,
ebiten.KeyG,
ebiten.KeyH,
ebiten.KeyU,
ebiten.KeyJ,
ebiten.KeyI,
ebiten.KeyK,
ebiten.KeyO,
ebiten.KeyL,
}
var keyStates = map[ebiten.Key]int{}
func init() {
for _, key := range keys {
keyStates[key] = 0
}
}
func updateInput() {
for _, key := range keys {
if !ebiten.IsKeyPressed(key) {
keyStates[key] = 0
continue
}
keyStates[key]++
}
}
var (
imagePiano *ebiten.Image
)
func init() {
var err error
imageEmpty, err := ebiten.NewImage(16, 16, ebiten.FilterNearest)
if err != nil {
panic(err)
}
imageEmpty.Fill(color.White)
imagePiano, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
if err != nil {
panic(err)
}
whiteKeys := []string{"A", "S", "D", "F", "G", "H", "J", "K", "L"}
width := 24
y := 48
for i, k := range whiteKeys {
x := i*width + 36
height := 112
op := &ebiten.DrawImageOptions{}
w, h := imageEmpty.Size()
op.GeoM.Scale(float64(width-1)/float64(w), float64(height)/float64(h))
op.GeoM.Translate(float64(x), float64(y))
op.ColorM.Scale(1, 1, 1, 1)
imagePiano.DrawImage(imageEmpty, op)
common.ArcadeFont.DrawText(imagePiano, k, x+8, y+height-16, 1, color.Black)
}
blackKeys := []string{"Q", "W", "", "R", "T", "", "U", "I", "O"}
for i, k := range blackKeys {
if k == "" {
continue
}
x := i*width + 24
height := 64
op := &ebiten.DrawImageOptions{}
w, h := imageEmpty.Size()
op.GeoM.Scale(float64(width-1)/float64(w), float64(height)/float64(h))
op.GeoM.Translate(float64(x), float64(y))
op.ColorM.Scale(0, 0, 0, 1)
imagePiano.DrawImage(imageEmpty, op)
common.ArcadeFont.DrawText(imagePiano, k, x+8, y+height-16, 1, color.White)
}
}
func update(screen *ebiten.Image) error {
updateInput()
for i, key := range keys {
if keyStates[key] != 1 {
continue
}
addNote(220*math.Exp2(float64(i-1)/12.0), 1.0)
}
screen.Fill(color.RGBA{0x80, 0x80, 0xc0, 0xff})
screen.DrawImage(imagePiano, nil)
ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %0.2f", ebiten.CurrentFPS()))
return nil
}
func main() {
if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Piano (Ebiten Demo)"); err != nil {
log.Fatal(err)
}
}