From 664f27d42187705237d863df91a8799202fc2262 Mon Sep 17 00:00:00 2001
From: Yongwei Xing <yongwei.xing@liulishuo.com>
Date: Tue, 2 Mar 2021 16:29:47 +0800
Subject: [PATCH] add rand circles

---
 example/example_randcircle.go |  26 +++++++
 julia.go                      |   6 +-
 randcircle.go                 | 130 ++++++++++++++++++++++++++++++++++
 utils.go                      |   4 ++
 4 files changed, 163 insertions(+), 3 deletions(-)
 create mode 100644 example/example_randcircle.go
 create mode 100644 randcircle.go

diff --git a/example/example_randcircle.go b/example/example_randcircle.go
new file mode 100644
index 0000000..847dcb0
--- /dev/null
+++ b/example/example_randcircle.go
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"generativeart"
+	"image/color"
+	"math/rand"
+	"time"
+)
+
+func main() {
+	rand.Seed(time.Now().Unix())
+	c := generativeart.NewCanva(500, 500, 2, 2)
+	c.SetBackground(generativeart.MistyRose)
+	c.SetLineWidth(1.0)
+	c.SetLineColor(color.RGBA{
+		R: 122,
+		G: 122,
+		B: 122,
+		A: 30,
+	})
+	c.SetColorSchema(generativeart.Plasma)
+	c.SetIterations(4)
+	c.FillBackground()
+	c.Draw(generativeart.NewRandCicle(30, 80, 0.2, 2, 10, 30, true))
+	c.ToPNG("randcircle.png")
+}
diff --git a/julia.go b/julia.go
index c80b6b9..433dafb 100644
--- a/julia.go
+++ b/julia.go
@@ -12,13 +12,13 @@ type julia struct {
 
 func NewJulia(formula GenFunc, maxz float64) *julia {
 	return &julia{
-		fn: formula,
+		fn:   formula,
 		maxz: maxz,
 	}
 }
 
 // Generative draws a julia set.
-func (j *julia)Generative(c *canva) {
+func (j *julia) Generative(c *canva) {
 	n := len(c.opts.colorSchema)
 	if n > 255 {
 		n = 255
@@ -37,4 +37,4 @@ func (j *julia)Generative(c *canva) {
 			c.img.Set(i, k, c.opts.colorSchema[idx])
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/randcircle.go b/randcircle.go
new file mode 100644
index 0000000..2bf9351
--- /dev/null
+++ b/randcircle.go
@@ -0,0 +1,130 @@
+package generativeart
+
+import (
+	"github.com/fogleman/gg"
+	"math"
+	"math/rand"
+)
+
+type circle struct {
+	x, y   float64
+	radius float64
+	dx, dy float64
+}
+
+type randCircle struct {
+	maxCircle         int
+	maxStepsPerCircle int
+	minSteps          float64
+	maxSteps          float64
+	minRadius         float64
+	maxRadius         float64
+	isRandColor	bool
+}
+
+func NewRandCicle(mc, msp int, minStep, maxStep, minr, maxr float64, isRandColor bool) *randCircle {
+	return &randCircle{
+		maxCircle:         mc,
+		maxStepsPerCircle: msp,
+		minSteps:          minStep,
+		maxSteps:          maxStep,
+		minRadius:         minr,
+		maxRadius:         maxr,
+		isRandColor: isRandColor,
+	}
+}
+
+func (r *randCircle) newCircleSlice(cn, w, h int) []circle {
+	var circles []circle
+
+	for i := 0; i < cn; i++ {
+		x := rand.Intn(w) + 1
+		y := rand.Intn(h) + 1
+		radius := float64(rand.Intn(int(r.minRadius))) + r.maxRadius - r.minRadius
+		angle := rand.Float64() * math.Pi * 2.0
+		step := r.minSteps + rand.Float64()*(r.maxSteps-r.minSteps)
+		circles = append(circles, circle{
+			x:      float64(x),
+			y:      float64(y),
+			radius: radius,
+			dx:     step * math.Cos(angle),
+			dy:     step * math.Sin(angle),
+		})
+	}
+
+	return circles
+}
+
+func (r *randCircle) circleSliceUpdate(cs []circle, w, h int) []circle {
+	var circles []circle
+
+	for _, c := range cs {
+		 c.x += c.dx
+		 c.y += c.dy
+
+		if c.x <= 0 {
+			c.x = 0
+			c.dx *= -1
+		}
+
+		if c.y <= 0 {
+			c.y = 0
+			c.dy *= -1
+		}
+
+		if c.x > float64(w) {
+			c.x = float64(w)
+			c.dx *= -1
+		}
+
+		if c.y > float64(h) {
+			c.y = float64(h)
+			c.dy *= -1
+		}
+
+		circles = append(circles, c)
+	}
+
+	return circles
+}
+
+// Generative draws a random circles image.
+func (r *randCircle) Generative(c *canva) {
+	ctex := gg.NewContextForRGBA(c.img)
+
+
+	for j := 0; j<c.opts.nIters; j++ {
+		cn := rand.Intn(r.maxCircle) + int(r.maxCircle/3)
+		circles := r.newCircleSlice(cn, c.width, c.height)
+
+		for i := 0; i < r.maxStepsPerCircle; i++ {
+			for _, c1 := range circles {
+				for _, c2 := range circles {
+
+					cl := c.opts.lineColor
+					if r.isRandColor {
+						cl = c.opts.colorSchema[rand.Intn(len(c.opts.colorSchema))]
+					}
+
+					if c1 == c2 {
+						continue
+					}
+
+					distance := Distance(c1.x, c1.y, c2.x, c2.y)
+
+					if distance <= c1.radius+c2.radius {
+						cx := (c1.x + c2.x) / 2
+						cy := (c1.y + c2.y) / 2
+
+						ctex.SetRGBA255(int(cl.R), int(cl.G), int(cl.B), 30)
+						ctex.SetLineWidth(c.opts.lineWidth)
+						ctex.DrawEllipse(cx, cy, distance/2, distance/2)
+						ctex.Stroke()
+					}
+				}
+			}
+
+			circles = r.circleSliceUpdate(circles, c.width, c.height)
+		}
+	}
+}
diff --git a/utils.go b/utils.go
index f26fa7e..e0c354e 100644
--- a/utils.go
+++ b/utils.go
@@ -33,3 +33,7 @@ func ConvertPolarToPixel(r, theta, xaixs, yaixs float64, h, w int) (int, int) {
 
 	return i, j
 }
+
+func Distance(x1, y1, x2, y2 float64) float64 {
+	return math.Sqrt(math.Pow(x1-x2, 2.0) + math.Pow(y1-y2, 2.0))
+}