From 966671b688e1ef8b9871e4839a98b95845a97404 Mon Sep 17 00:00:00 2001
From: Yongwei Xing <yongwei.xing@liulishuo.com>
Date: Wed, 3 Mar 2021 16:12:50 +0800
Subject: [PATCH] add circle loop

---
 circleloop.go                 | 39 +++++++++++++++++++++++++++++++++++
 example/example_circleloop.go | 20 ++++++++++++++++++
 2 files changed, 59 insertions(+)
 create mode 100644 circleloop.go
 create mode 100644 example/example_circleloop.go

diff --git a/circleloop.go b/circleloop.go
new file mode 100644
index 0000000..e2048c0
--- /dev/null
+++ b/circleloop.go
@@ -0,0 +1,39 @@
+package generativeart
+
+import (
+	"github.com/fogleman/gg"
+	"math"
+)
+
+type circleLoop struct {
+	radius float64
+}
+
+func NewCircleLoop(radius float64) *circleLoop {
+	return &circleLoop{
+		radius: radius,
+	}
+}
+
+// Generative draws a Circle Loop images.
+func (cl *circleLoop) Generative(c *canva) {
+	ctex := gg.NewContextForRGBA(c.img)
+
+	r := cl.radius
+	var theta float64 = 0
+	for i:=0; i<c.opts.nIters; i++ {
+		ctex.Push()
+		ctex.Translate(float64(c.width/2), float64(c.height/2))
+		x := cl.radius*math.Cos(gg.Radians(theta))
+		y := cl.radius*math.Sin(gg.Radians(theta*2))
+
+		ctex.SetLineWidth(c.opts.lineWidth)
+		ctex.SetColor(c.opts.lineColor)
+		ctex.SetRGBA255(int(c.opts.lineColor.R), int(c.opts.lineColor.G), int(c.opts.lineColor.B), c.opts.alpha)
+		ctex.DrawEllipse(x, y, r/2, r/2)
+		ctex.Stroke()
+		ctex.Pop()
+		r+=math.Cos((theta))*math.Sin((theta/2))+math.Sin((theta))*math.Cos((theta/2))
+		theta += math.Pi/2
+	}
+}
diff --git a/example/example_circleloop.go b/example/example_circleloop.go
new file mode 100644
index 0000000..fb2b527
--- /dev/null
+++ b/example/example_circleloop.go
@@ -0,0 +1,20 @@
+package main
+
+import (
+	"generativeart"
+	"math/rand"
+	"time"
+)
+
+func main() {
+	rand.Seed(time.Now().Unix())
+	c := generativeart.NewCanva(500, 500, 2, 2)
+	c.SetBackground(generativeart.Black)
+	c.SetLineWidth(1)
+	c.SetLineColor(generativeart.Orange)
+	c.SetAlpha(30)
+	c.SetIterations(1000)
+	c.FillBackground()
+	c.Draw(generativeart.NewCircleLoop(100))
+	c.ToPNG("circleloop.png")
+}