package main

import (
    "fmt"
    "math"
)

const (
    width, height = 1200, 820
    cells         = 100
    xyrange       = 30.0
    xyscale       = width / 2 / xyrange
    zscale        = height * 0.4
    angle         = math.Pi / 6
)

var sin30, cos30 = math.Sin(angle), math.Cos(angle)

func main() {

    fmt.Printf("<svg xmlns='http://www.w3.org/2000/svg' "+
        "style='stroke: blue; fill: white; stroke-width: 1.0' "+
        "width='%d' height='%d'>", 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.Printf("<polygon points='%g,%g,%g,%g,%g,%g,%g,%g'/>\n", ax, ay, bx, by, cx, cy, dx, dy)

        }
    }
    fmt.Println("</svg>")
}

func corner(i, j int) (float64, float64) {
    x := xyrange * (float64(i)/cells - 0.5)
    y := xyrange * (float64(j)/cells - 0.5)
    z := f(x, y)

    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)
    return math.Sin(r) / r
}