random circles example

cmd/playground/circles/circles.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"math/rand"
+	"image"
+	"image/color"
+	"image/draw"
+	"image/png"
+	"os"
+
+	iu "git.nkpl.cc/twocookedfaggots/imageutils"
+)
+
+func square(side int) image.Rectangle { return image.Rect(0, 0, side, side) }
+
+func Circles(b image.Rectangle, radius int) chan iu.Circle {
+	ch := make(chan iu.Circle)
+	go func() {
+		defer close(ch)
+		for {
+			x, y := rand.Int()%b.Dx(), rand.Int()%b.Dy()
+			dxdy := b.Dx()*b.Dy()
+			r := rand.Int() % (dxdy/(dxdy/radius))
+			ch <- iu.Circle{image.Point{x, y}, r}
+		}
+	}()
+	return ch
+}
+
+// Converts color.Opaque and color.Transparent to color.Black and color.White respectively.
+var BlackAndWhite = color.ModelFunc(
+	func(c color.Color) color.Color {
+		if color.AlphaModel.Convert(c) == color.Opaque {
+			return color.Black
+		}
+		return color.White
+	},
+)
+
+func main() {
+	canvas := image.NewRGBA(square(1024))
+	circles := Circles(canvas.Bounds(), 1024/16)
+
+	// draw n circles
+	for i := 0; i < 100; i++ {
+		c := <-circles
+		draw.DrawMask(
+			canvas, canvas.Bounds(), &image.Uniform{color.White}, 
+			image.Point{}, c, image.Point{}, draw.Over,
+		)
+	}
+	err := png.Encode(os.Stdout, canvas)
+	if err != nil {
+		panic(err)
+	}
+}