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Mandelbrot in Go 🏃♂️
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| package main | |
| import ( | |
| "os" | |
| "math" | |
| "image" | |
| "flag" | |
| "image/png" | |
| "image/color" | |
| ) | |
| func scale(value float64, minA float64, maxA float64, minB float64, maxB float64) float64 { | |
| // Scales a float from number range A to range B. | |
| return ((value / (math.Abs(minA) + math.Abs(maxA))) * (math.Abs(minB) + math.Abs(maxB))) + minB | |
| } | |
| func mandelbrotColors() [16]color.RGBA { | |
| // RGBA colors from https://stackoverflow.com/a/16505538 | |
| return [...]color.RGBA { | |
| color.RGBA{66, 30, 15, 255}, | |
| color.RGBA{25, 7, 26, 255}, | |
| color.RGBA{9, 1, 47, 255}, | |
| color.RGBA{4, 4, 73, 255}, | |
| color.RGBA{0, 7, 100, 255}, | |
| color.RGBA{12, 44, 138, 255}, | |
| color.RGBA{24, 82, 177, 255}, | |
| color.RGBA{57, 125, 209, 255}, | |
| color.RGBA{134, 181, 229, 255}, | |
| color.RGBA{211, 236, 248, 255}, | |
| color.RGBA{241, 244, 191, 255}, | |
| color.RGBA{248, 201, 95, 255}, | |
| color.RGBA{255, 170, 0, 255}, | |
| color.RGBA{204, 128, 0, 255}, | |
| color.RGBA{153, 87, 0, 255}, | |
| color.RGBA{106, 52, 3, 255}, | |
| } | |
| } | |
| func CreateMandelbrotImage(width int, height int, maxIteration int, colors [16]color.RGBA) *image.RGBA { | |
| // Creates an in memory image and fills it pixel by pixel with mandelbrotColors | |
| mandelbrotImage := image.NewRGBA(image.Rect(0, 0, width, height)) | |
| // Implementation of https://en.wikipedia.org/wiki/Mandelbrot_set#Escape_time_algorithm | |
| for Px := 0; Px < width; Px++ { | |
| for Py := 0; Py < height; Py++ { | |
| var x0 float64 = scale(float64(Px), 0, float64(width), -2.5, 1); | |
| var y0 float64 = scale(float64(Py), 0, float64(height), -1, 1); | |
| var x, y float64 = 0, 0; | |
| iteration := 0; | |
| for ; x*x + y*y < 2*2 && iteration < maxIteration; iteration++ { | |
| xTemp := x*x - y*y + x0; | |
| y = 2*x*y + y0; | |
| x = xTemp; | |
| } | |
| color := colors[(iteration % len(colors))] | |
| mandelbrotImage.Set(Px, Py, color) | |
| } | |
| } | |
| return mandelbrotImage | |
| } | |
| func main() { | |
| var width, height, iteration int | |
| flag.IntVar(&width, "w", 1000, "specify width to use. defaults to 1024.") | |
| flag.IntVar(&height, "h", 600, "specify height to use. defaults to 1024.") | |
| flag.IntVar(&iteration, "i", 10, "specify iterations to use. defaults to 40.") | |
| flag.Parse() | |
| img := CreateMandelbrotImage(width, height, iteration, mandelbrotColors()) | |
| file, err := os.Create("mandelbrot.png") | |
| if err != nil { | |
| panic(err) | |
| } | |
| defer file.Close() | |
| png.Encode(file, img) | |
| } |
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