bresenham_circle.go

package main

import (
	"image"
	"image/color"
	"image/png"
	"math/rand"
	"os"
	"time"
)

func symmetricDraw(img *image.RGBA, offX, offY, x, y int, color color.Color) {
	pixels := [8][2]int{
		{x, y}, {y, x}, {x, -y}, {-y, x}, {-x, y}, {y, -x}, {-x, -y}, {-y, -x},
	}
	for _, p := range pixels {
		img.Set(offX+p[0], offY+p[1], color)
	}
}

func drawCircle(img *image.RGBA, offX, offY, r int, color color.Color) {
	x := 0
	y := r
	h := 1 - r
	symmetricDraw(img, offX, offY, x, y, color)

	for y >= x {
		if h < 0 {
			h += 2*x + 3
			x++

		} else {
			h += 2*(x-y) + 5
			x++
			y--
		}
		symmetricDraw(img, offX, offY, x, y, color)
	}
}

func main() {
	width := 1000
	height := 1000

	rand.Seed(time.Now().Unix())
	black := color.RGBA{0, 0, 0, 0xff}

	upLeft := image.Point{0, 0}
	lowRight := image.Point{width, height}
	img := image.NewRGBA(image.Rectangle{upLeft, lowRight})

	for i := 0; i < width; i++ {
		for j := 0; j < height; j++ {
			img.Set(i, j, black)
		}
	}

	for i := 0; i < 123; i++ {
		radius := 10 + rand.Intn(70)
		posX := rand.Intn(1000)
		posY := rand.Intn(1000)
		drawCircle(img, posX, posY, radius, color.RGBA{
			uint8(rand.Intn(256)), uint8(rand.Intn(256)), uint8(rand.Intn(256)), 0xff,
		})
	}

	f, _ := os.Create("image.png")
	_ = png.Encode(f, img)
}