main.go

package main

import (
	"fmt"
	"image"
	"math"
	"os"
	"sync"

	"github.com/disintegration/gift"
	"golang.org/x/image/tiff"
)

var w = float64(1200)
var h = float64(1200)

func main() {
	var wg sync.WaitGroup
	wg.Add(1)

	go draw(0.0, &wg)
	// go draw("image2.tiff", 0.1, &wg)
	// go draw("image3.tiff", 0.2, &wg)
	// go draw("image4.tiff", 0.3, &wg)

	wg.Wait()
}

func plot(x float64, y float64) (int, int) {
	return int(x*(w/4-2) + w/2), int(y*(w/4-2) + w/2)
}

func draw(seed float64, wg *sync.WaitGroup) {
	defer wg.Done()
	r := image.Rectangle{image.Point{0, 0}, image.Point{int(w), int(h)}}

	a := float64(1.141914030)
	b := float64(-2.28415230)
	c := float64(2.42754030)
	d := float64(-2.1771960)

	// a = 3.1857827494137165
	// b = -0.3198765697284589
	// c = 2.360541685422172
	// d = 3.7715199253585237

	// Trying out some different numbers...
	a, b, c, d = -3.691189689088887, -1.6092399803788613, -3.237184177967544, 1.0777434951897948
	a, b, c, d = 0.9007053969634278, -2.637442325264809, 1.7301797869949507, -3.9470323418777316
	a, b, c, d = 2.503099257297462, -3.368168279026971, 1.0470005061998595, 100.21597068244601
	a, b, c, d = -3.1786357692725513, -2.5369374008830796, -1.3966670936288477, -1.1863296941409676
	a, b, c, d = -3.500319454310196, -2.274038540095157, 2.197560305067105, -3.341233355959094
	a, b, c, d = -3.3961435716410797, -3.6251089470068134, -3.928629774986387, -1.8938605382165878
	a, b, c, d = -1.2172606689053183, 3.238552831567606, 0.4987222602920749, 3.4832339552396494

	name := fmt.Sprintf("image-%f,%f,%f,%f.tiff", a, b, c, d)
	img := image.NewGray16(r)
	f, err := os.Create(name)
	if err != nil {
		panic(err)
	}
	defer f.Close()
	x := float64(seed)
	y := float64(seed)
	xn := float64(0)
	yn := float64(0)

	max := uint16(0)

	n := 0

	for true {
		xn = math.Sin(a*y) - math.Cos(b*x)
		yn = math.Sin(c*x) - math.Cos(d*y)
		// fmt.Printf("%-2.2f, %-2.2f\n", xn, yn)

		sx, sy := plot(xn, yn)
		color := img.Gray16At(sx, sy)
		if color.Y >= uint16(65535) {
			break
		}
		// Factors of 65535 .. 1, 3, 5, 15, 17, 51, 85, 255, 257, 771, 1285, 3855, 4369, 13107, 21845.
		color.Y += 15
		img.SetGray16(sx, sy, color)

		if color.Y >= max {
			max = color.Y
		}

		if n%10000000 == 0 {
			fmt.Printf("seed %1.1f max: %d n:%d\n", seed, max, n)
		}
		n = n + 1

		x = xn
		y = yn
	}

	g := gift.New(
		gift.ColorspaceLinearToSRGB(),
		gift.Gamma(2.5),
		gift.Invert(),
	)

	img2 := image.NewGray16(r)

	g.Draw(img2, img)

	tiff.Encode(f, img2, nil)
}