修改Lissajous程序，修改其调色板来生成更丰富的颜色，

[问答题]

修改Lissajous程序，修改其调色板来生成更丰富的颜色，然后修改SetColorIndex的第三个参数，看看显示结果吧。

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                package main
import (
"image"
"image/color"
"image/gif"
"io"
"math"
"math/rand"
"os"
)
<br>//定义调色板
var palette = []color.Color{
                  color.RGBA{255,255,255,math.MaxUint8}, color.Black,
                  color.RGBA{0,0,128,math.MaxUint8},color.RGBA{30,144,255,math.MaxUint8},color.RGBA{72,61,139,math.MaxUint8},color.RGBA{255,0,255,math.MaxUint8},color.RGBA{124,252,0,math.MaxUint8}}
const (
whiteIndex = 0 // first color in palette
blackIndex = 1 // next color in palette
greenIndex = 2 // next color in palette 定义新的颜色
)
func main() {
lissajous(os.Stdout)
}
func lissajous(out io.Writer) {
const (
cycles  = 5     // number of complete
                  x oscillator revolutions
res     = 0.001 // angular resolution
size    = 100   // image canvas covers
                  [-size..+size]
nframes = 128    // number of
                  animation frames
delay   = 8     // delay between
                  frames in 10ms units
)
freq := rand.Float64() * 3.0 // relative
                  frequency of y oscillator
anim := gif.GIF{LoopCount: nframes}
phase := 0.0 // phase difference
for i,c := 0,1; i < nframes; i++ {
rect := image.Rect(0, 0, 2*size+1,
                  2*size+1)
img := image.NewPaletted(rect,
                  palette)
for t := 0.0; t < cycles*2*math.Pi;
                  t += res {
x := math.Sin(t)
y := math.Sin(t*freq + phase)
img.SetColorIndex(size+int(x*size+0.5),
                  size+int(y*size+0.5),uint8(c)) //使用新的颜色
}
c ++ //修改颜色选择
if c >= len(palette) {
c = 1
}
phase += 0.1
anim.Delay = append(anim.Delay, delay)
anim.Image = append(anim.Image, img)
}
gif.EncodeAll(out, &anim) // NOTE:
                  ignoring encoding errors
}         
         
         
         
      
       