go语言制作一个gif动态图

rotate.go

package main
import (
  "github.com/hydra13142/cube"
  "github.com/hydra13142/geom"
  "github.com/hydra13142/paint"
  "image"
  "image/color/palette"
  "image/gif"
  "math"
  "os"
)
var (
  pln   *cube.Plain
  unx, uny cube.Vector
)
const (
  H = 9
  W = 36
)
func init() {
  pln, _ = cube.NewPlain(cube.Point{}, cube.Vector{4, 4, 3})
  uny = cube.FromTo(cube.Point{}, pln.VerticalPoint(cube.Point{0, 0, 10})).Unit()
  unx = cube.OuterProduct(uny, cube.Vector{4, 4, 3}).Unit()
}
func main() {
  var x [H*W + 1]cube.Point
  var y [H*W + 1]geom.Point
  dxy := (math.Pi * 2) / W
  dz := math.Pi / H
  for i := 0; i <= H*W; i++ {
    az := float64(i)*dz/W - math.Pi/2
    r := 140 * math.Cos(az)
    z := 140 * math.Sin(az) 
    axy := float64(i) * dxy
    x[i] = cube.Point{math.Cos(axy) * r, math.Sin(axy) * r, z}
  }
  pics := make([]*image.Paletted, 0, 20)
  img := paint.Image{
    FR: paint.Green,
    BG: paint.White,
  }
  stp := math.Pi * 2 / (W * 3)
  delay := make([]int, 0, 3*W)
  for t := 0; t < 3*W; t++ {
    img.Image = image.NewPaletted(image.Rect(0, 0, 300, 300), palette.Plan9)
    for i := 0; i <= H*W; i++ {
      ox := cube.FromTo(cube.Point{}, x[i])
      y[i] = geom.Point{cube.InnerProduct(ox, unx), cube.InnerProduct(ox, uny)}
      a, b := x[i].X, x[i].Z
      x[i].X = a*math.Cos(stp) - b*math.Sin(stp)
      x[i].Z = b*math.Cos(stp) + a*math.Sin(stp)
    }
    img.Line(
      150+int(y[0].X),
      150-int(y[0].Y),
      150+int(y[H*W].X),
      150-int(y[H*W].Y),
    )
    for i := 0; i < H*W; i++ {
      img.Line(
        150+int(y[i].X),
        150-int(y[i].Y),
        150+int(y[i+1].X),
        150-int(y[i+1].Y),
      )
    }
    pics = append(pics, img.Image.(*image.Paletted))
    delay = append(delay, 8)
  }
  file, _ := os.Create("rotate.gif")
  defer file.Close()
  gif.EncodeAll(file, &gif.GIF{
    Image:   pics,
    Delay:   delay,
    LoopCount: 5 * len(delay),
  })
}