add art

art/mandelbrot.go

@@ -0,0 +1,64 @@
+//NOT FINISHED
+
+package main
+
+import (
+	"image"
+	"image/png"
+	"math/cmplx"
+	"os"
+)
+
+type Color struct {
+	r uint32
+	g uint32
+	b uint32
+	a uint32
+}
+
+func (c Color) RGBA() (r, g, b, a uint32) {
+	return c.r, c.g, c.b, c.a
+}
+
+func green() Color {
+	return Color{0, 255, 0, 255}
+}
+
+func blue() Color {
+	return Color{0, 0, 255, 255}
+}
+
+func main() {
+	f, err := os.Create("out.png")
+	if err != nil {
+		os.Exit(1)
+	}
+	const (
+		xmin, ymin, xmax, ymax = -2, -2, +2, +2
+		width, height          = 1024, 1024
+	)
+	img := image.NewRGBA(image.Rect(0, 0, width, height))
+	for py := 0; py < height; py++ {
+		y := float64(py)/height*(ymax-ymin) + ymin
+		for px := 0; px < width; px++ {
+			x := float64(px)/width*(xmax-xmin) + xmin
+			z := complex(x, y)
+			img.Set(px, py, mandelbrot(z))
+		}
+	}
+	png.Encode(f, img)
+	f.Close()
+}
+
+func mandelbrot(z complex128) Color {
+	const iterations = 200
+	const contrast = 15
+	var v complex128
+	for n := uint8(0); n < iterations; n++ {
+		v = v*v + z
+		if cmplx.Abs(v) > 2 {
+			return Color{0, uint32(255 - contrast*n), 0, 255}
+		}
+	}
+	return blue()
+}