Scribble a heart

heart.go

package main

import (
	"fmt"
	"math"
	"math/rand"
	"os"
	"time"

	"github.com/ajstarks/svgo"
)

var canvas *svg.SVG

func abs(d int) int {
	if d < 0 {
		return -d
	}
	return d
}

func jitter(d int, dir int) (float64, float64) {
	d = distance(d, rand.Intn(2)+1, dir)
	return heart(d)
}

func distance(d int, travel int, dir int) int {
	for i := 0; i < travel; i++ {
		d = d + dir
	}
	return d
}

func deg2rad(d int) float64 {
	return (float64(d) / 360.0) * 2 * math.Pi
}

func heart(d int) (float64, float64) {
	r := deg2rad(d)
	x := 16 * math.Pow(math.Sin(r), 3)
	y := 13*math.Cos(r) - 5*math.Cos(2*r) - 2*math.Cos(3*r) + 0.1*math.Cos(4*r)
	return x, y
}

func line(d0, d1 int) {
	fmt.Fprintf(os.Stderr, "Line from %d to %d\n", d0, d1)
	px, py := heart(d0)
	x, y := heart(d1)

	sx := 200 + int(10*px)
	sy := 400 - (200 + int(10*py))
	ex := 200 + int(10*x)
	ey := 400 - (200 + int(10*y))

	if os.Getenv("FLIP") != "" {
		sx = 400 - sx
		ex = 400 - ex
	}
	canvas.Line(sx, sy, ex, ey, "stroke:green;stroke-width:1")
}

func main() {
	px := 99999.0
	py := 0.0

	rand.Seed(time.Now().Unix())

	canvas = svg.New(os.Stdout)
	canvas.Start(400, 400)

	ds := 10
	de := 120

	for {
		if de-ds < 15 {
			break
		}
		line(ds, de)
		ds = distance(ds, rand.Intn(4)+rand.Intn(2)+1, +1)
		line(de, ds)
		de = distance(de, rand.Intn(4)+rand.Intn(2)+1, -1)
	}
	ds = 120
	de = 350
	for {
		if de-ds < 15 {
			break
		}
		line(ds, de)
		ds = distance(ds, rand.Intn(4)+rand.Intn(2)+1, +1)
		if abs(ds-180) < 20 {
			ds = distance(ds, rand.Intn(4)+3, +1)
		}
		line(de, ds)
		de = distance(de, rand.Intn(4)+rand.Intn(2)+1, -1)
		if de < 270 {
			de = distance(de, rand.Intn(4)+3, -1)
		}
	}

	canvas.End()
}