gomand

mand.go

package main

import (
    "bufio"
    "log"
    "os"
    //"fmt"
    "unsafe"
    )

func mand(c complex64) int {
    var z complex64
    z = 0+0i
    iter := 0
    for {
        z = z*z + c
	iter += 1
	zr := real(z)
	zi := imag(z)
	if (iter >= 250 || (zr*zr + zi*zi > 4.0)) {
	    break
	    }
	}
    return iter
    }

func xform(x int, y int) complex64 {
    var a float32
    var b float32
    a = float32(x)
    b = float32(y)
    return complex(-2.0 + 4.0*(a/500.0), 2.0 - 4.0*(b/500.0))
    }

type RGB24 struct {
  Red uint8
  Green uint8
  Blue uint8
  }

type ByteSliceRGB struct {
  Addr *RGB24
  Len int
  Cap int
  }
  
func output(w *bufio.Writer, i int) {
    pix := RGB24{ uint8(i), uint8(i/2), 0, }
    slice := &ByteSliceRGB{&pix, 3, 3}  // struct 3 bytes long
    var byteSlice []byte = *(*[]byte)(unsafe.Pointer(slice))
    w.Write(byteSlice)
    }
    
func main() {
    var i int
    var x int
    var y int

    file, err := os.Create("./kuva.ppm")
    if err != nil {
        log.Fatal(err)
    }
    writer := bufio.NewWriter(file)
    writer.WriteString("P6\n500 500\n255\n")
    
    y = 0
    for y < 500 {
        x = 0
        for x < 500 {
	    i = mand(xform(x, y))
	    output(writer, i)
            x++
	    }
      y++
    }
    writer.Flush()
    
}