From a92fa10eb14148a76664087838a1f8e37abd70de Mon Sep 17 00:00:00 2001
From: Yongwei Xing <yongwei.xing@liulishuo.com>
Date: Tue, 2 Mar 2021 18:02:47 +0800
Subject: [PATCH] add circle line

---
 circleline.go                 | 52 +++++++++++++++++++++++++++++++++++
 example/example_circleline.go | 18 ++++++++++++
 2 files changed, 70 insertions(+)
 create mode 100644 circleline.go
 create mode 100644 example/example_circleline.go

diff --git a/circleline.go b/circleline.go
new file mode 100644
index 0000000..5561e8d
--- /dev/null
+++ b/circleline.go
@@ -0,0 +1,52 @@
+package generativeart
+
+import (
+	"github.com/fogleman/gg"
+	"math"
+	"math/rand"
+)
+
+type point struct {
+	x, y float64
+}
+
+type circleLine struct {
+	step    float64
+	lineNum int
+	radius  float64
+}
+
+// NewCircleLine returns a circleLine object.
+func NewCircleLine(step float64, lineNum int, radius float64) *circleLine {
+	return &circleLine{
+		step:    step,
+		lineNum: lineNum,
+		radius:  radius,
+	}
+}
+
+// Generative draws a cirle line image.
+func (cl *circleLine) Generative(c *canva) {
+	ctex := gg.NewContextForRGBA(c.img)
+	ctex.SetLineWidth(c.opts.lineWidth)
+	ctex.SetColor(c.opts.lineColor)
+	var points []point
+	for theta := -math.Pi; theta <= math.Pi; theta += cl.step {
+		x := cl.radius * math.Cos(theta)
+		y := cl.radius * math.Sin(theta)
+		xi, yi := ConvertCartesianToPixel(x, y, c.xaixs, c.yaixs, c.width, c.height)
+		points = append(points, point{
+			x: float64(xi),
+			y: float64(yi),
+		})
+	}
+
+	for i := 0; i < cl.lineNum; i++ {
+		p1 := points[rand.Intn(len(points))]
+		p2 := points[rand.Intn(len(points))]
+
+		ctex.MoveTo(p1.x, p1.y)
+		ctex.LineTo(p2.x, p2.y)
+		ctex.Stroke()
+	}
+}
diff --git a/example/example_circleline.go b/example/example_circleline.go
new file mode 100644
index 0000000..e6a35a5
--- /dev/null
+++ b/example/example_circleline.go
@@ -0,0 +1,18 @@
+package main
+
+import (
+	"generativeart"
+	"math/rand"
+	"time"
+)
+
+func main() {
+	rand.Seed(time.Now().Unix())
+	c := generativeart.NewCanva(800, 800, 2, 2)
+	c.SetBackground(generativeart.Tan)
+	c.SetLineWidth(1.0)
+	c.SetLineColor(generativeart.Lavender)
+	c.FillBackground()
+	c.Draw(generativeart.NewCircleLine(0.02, 600, 1.5))
+	c.ToPNG("circleline.png")
+}