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main.go
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main.go
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package main
import (
"fmt"
"io"
"log"
"math"
"net/http"
)
const (
width, height = 600, 320 // 以像素表示的画布大小
cells = 100 // 网格单元的个数
xyrange = 30.0 // 坐标轴的范围,-xyrange ~ xyrange
xyscale = width / 2 / xyrange // x 或 y 轴上每个单位长度的像素
zscale = height * 0.4 // z轴上每个单位长度的像素
angle = math.Pi / 6 // x、y轴的角度,30度
color = "grey" // 线条的颜色
)
var sin30, cos30 = math.Sin(angle), math.Cos(angle)
func svg(w io.Writer) {
_, _ = fmt.Fprintf(w, "<svg xmlns='http://www.w3.org/2000/svg' "+
"style='stroke: %s; fill: white; stroke-width: 0.7' "+
"width='%d' height='%d'>", color, width, height)
for i := 0; i < cells; i++ {
for j := 0; j < cells; j++ {
ax, ay := corner(i+1, j)
bx, by := corner(i, j)
cx, cy := corner(i, j+1)
dx, dy := corner(i+1, j+1)
_, _ = fmt.Fprintf(w, "<polygon points='%g,%g %g,%g %g,%g %g,%g'/>\n",
ax, ay, bx, by, cx, cy, dx, dy)
}
}
_, _ = fmt.Fprintln(w, "</svg>")
}
func corner(i, j int) (float64, float64) {
// 求出网格单元(i,j)的顶点坐标(x,y)
x := xyrange * (float64(i)/cells - 0.5)
y := xyrange * (float64(j)/cells - 0.5)
// 计算曲面高度z
z := f(x, y)
// 将(x,y,z)等角投射到二维SVG绘图平面上,坐标是(sx,sy)
sx := width/2 + (x-y)*cos30*xyscale
sy := height/2 + (x+y)*sin30*xyscale - z*zscale
return sx, sy
}
func f(x, y float64) float64 {
r := math.Hypot(x, y) // 到(0,0)的距离
return math.Sin(r) / r
}
func main() {
handler := func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "image/svg+xml")
svg(w)
}
http.HandleFunc("/", handler)
log.Fatal(http.ListenAndServe("localhost:8081", nil))
}