github.com/cznic/mathutil@v0.0.0-20181122101859-297441e03548/example2/example2.go (about)

     1  // Copyright (c) 2011 CZ.NIC z.s.p.o. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // blame: jnml, labs.nic.cz
     6  
     7  // +build ignore
     8  
     9  package main
    10  
    11  import (
    12  	"bytes"
    13  	"github.com/cznic/mathutil"
    14  	"image"
    15  	"image/png"
    16  	"io/ioutil"
    17  	"log"
    18  	"math"
    19  	"math/rand"
    20  )
    21  
    22  // $ go run example2.go # view rand.png and rnd.png by your favorite pic viewer
    23  //
    24  // see http://www.boallen.com/random-numbers.html
    25  func main() {
    26  	sqr := image.Rect(0, 0, 511, 511)
    27  	r, err := mathutil.NewFC32(math.MinInt32, math.MaxInt32, true)
    28  	if err != nil {
    29  		log.Fatal("NewFC32", err)
    30  	}
    31  
    32  	img := image.NewGray(sqr)
    33  	for y := 0; y < 512; y++ {
    34  		for x := 0; x < 512; x++ {
    35  			if r.Next()&1 != 0 {
    36  				img.Set(x, y, image.White)
    37  			}
    38  		}
    39  	}
    40  	buf := bytes.NewBuffer(nil)
    41  	if err := png.Encode(buf, img); err != nil {
    42  		log.Fatal("Encode rnd.png ", err)
    43  	}
    44  
    45  	if err := ioutil.WriteFile("rnd.png", buf.Bytes(), 0666); err != nil {
    46  		log.Fatal("ioutil.WriteFile/rnd.png ", err)
    47  	}
    48  
    49  	r2 := rand.New(rand.NewSource(0))
    50  	img = image.NewGray(sqr)
    51  	for y := 0; y < 512; y++ {
    52  		for x := 0; x < 512; x++ {
    53  			if r2.Int()&1 != 0 {
    54  				img.Set(x, y, image.White)
    55  			}
    56  		}
    57  	}
    58  	buf = bytes.NewBuffer(nil)
    59  	if err := png.Encode(buf, img); err != nil {
    60  		log.Fatal("Encode rand.png ", err)
    61  	}
    62  
    63  	if err := ioutil.WriteFile("rand.png", buf.Bytes(), 0666); err != nil {
    64  		log.Fatal("ioutil.WriteFile/rand.png ", err)
    65  	}
    66  }