surface02

surface/surface.go

@@ -3,43 +3,79 @@ package main
 import (
 	"fmt"
 	"math"
+	"net/http"
+	"strconv"
 )
 
-const (
-	width, height = 600, 320
-	cells         = 100
-	xyrange       = 30.0
-	xyscale       = width / 2 / xyrange
-	zscale        = height * 0.4
-	angle         = math.Pi / 6
-)
+var height, width float64 = 300, 600
+var cells float64 = 100                   // number of grid cells
+var xyrange float64 = 30.0                // axis ranges (-xyrange..+xyrange)
+var xyscale float64 = width / 2 / xyrange // pixels per x or y unit
+var zscale float64 = height * 0.4         // pixels per z unit
+var angle float64 = math.Pi / 6           // angle of x, y axes (=30°)
 
-var sin30, cos30 = math.Sin(angle), math.Cos(angle)
+var sin30, cos30 = math.Sin(angle), math.Cos(angle) // sin(30°), cos(30°)
 
 func main() {
-	fmt.Printf("<svg xmlns='http://www.w3.org/2000/svg'"+
-		"style='stroke: grey; fill: white; stroke-width:0.7' "+
+
+	//http服务
+	http.HandleFunc("/", handle)
+	http.ListenAndServe("0.0.0.0:8000", nil)
+}
+func handle(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "image/svg+xml")
+	if err := r.ParseForm(); err != nil {
+		return
+	}
+	//var height int
+	//var width  int
+	for k, v := range r.Form {
+		if k == "height" {
+			h, _ := strconv.ParseFloat(v[0], 64)
+			if h > 0 {
+				height = h
+			}
+		}
+		if k == "width" {
+			w, _ := strconv.ParseFloat(v[0], 64)
+			if w > 0 {
+				width = w
+			}
+		}
+	}
+	xyscale = width / 2 / xyrange
+	zscale = height * 0.4
+	fmt.Fprintf(w, "<svg xmlns='http://www.w3.org/2000/svg' "+
+		"style='stroke: #ff0000; fill: #0000ff; stroke-width: 0.7' "+
 		"width='%d' height='%d'>", width, height)
-	for i := 0; i < cells; i++ {
-		for j := 0; j < cells; j++ {
+	for i := 0; i < int(cells); i++ {
+		for j := 0; j < int(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.Fprintf(w, "<polygon points='%g,%g %g,%g %g,%g %g,%g'/>\n",
+				ax, ay, bx, by, cx, cy, dx, dy)
 		}
-		fmt.Println("</svg>")
 	}
+	fmt.Fprintf(w, "</svg>")
+
 }
 func corner(i, j int) (float64, float64) {
+	// Find point (x,y) at corner of cell (i,j).
 	x := xyrange * (float64(i)/cells - 0.5)
-	y := xyrange * (float64(i)/cells - 0.5)
+	y := xyrange * (float64(j)/cells - 0.5)
+
+	// Compute surface height z.
 	z := f(x, y)
+
+	// Project (x,y,z) isometrically onto 2-D SVG canvas (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)
-	return math.Sin(r)
+	r := math.Hypot(x, y) // distance from (0,0)
+	return math.Sin(r) / r
 }