Mandlebrot set in Go

 

 

Mandlebrot

 

Mandlebrot set program in Go based on original ps5.js program by Codingtrain

package main

import (
    "fmt"
    "image"
    "image/png"
    "image/color"
    "os"
)

func main() {
    
    // set image width and height in pixels
    image_width := 1000
    image_height := 1000

    // Create a blank image
    myImage := image.NewRGBA(image.Rect(0, 0, image_width, image_height))

    
    // set (w)idth and (h)eight. Set h based on w scaled by image ratio
    w := 3.0
    h := (w * float64(image_height)) / float64(image_width)
    

    // start at negative half the width and height
    xmin := -w/2
    ymin := -h/2
    
    // maximum number of iterations for each point on the complex plane
    // if we dont reach infinty in maxiterations then assume we never will
    maxiterations := 100;
    
    // x goes from xmin to xmax
    xmax := xmin + w
    
    // y goes from ymin to ymax
    ymax := ymin + h
    
    // calculate amount we increment x, y for each pixel
    dx := (xmax - xmin) / float64(image_width)
    dy := (ymax - ymin) / float64(image_height)
    
    
    //start y
    y := ymin
    
    for j:=0; j < image_height; j++ {
        // start x
        x := xmin
       
        for i:=0; i < image_width; i++ {
           
            //now we test, as we iteate z = z^2 + cm does z tend towards infinity?
           
            a := x
            b := y
            n := 0
           
            for n < maxiterations {
                aa := a * a
                bb := b * b
                twoab := 2.0 * a * b
                a = aa - bb + x
                b = twoab + y
                // infintiy in our finite world is simple, let's just consider it 16
                if (a*a + b*b) > 16 {
                    break
                }
                n++
            }
           
            if (n==maxiterations) {
                myImage.Set(i, j, color.RGBA{0, 0, 0, 255})
            } else {
                myImage.Set(i, j, color.RGBA{uint8(n)*16, 0, 0, 255})
            }
            x += dx
        }
        y += dy
    }
    
    // outputFile is a File type which satisfies Writer interface
    outputFile, err := os.Create("test.png")
    if err != nil {
        // Handle error
    }

    // Encode takes a writer interface and an image interface
    // We pass it the File and the RGBA
    png.Encode(outputFile, myImage)

    // Don't forget to close files
    outputFile.Close()   
}