From 05f31aca8eda86d2ebc11b1adfa363271f396690 Mon Sep 17 00:00:00 2001
From: Yongwei Xing <yongwei.xing@liulishuo.com>
Date: Tue, 2 Mar 2021 17:11:26 +0800
Subject: [PATCH] add silk smoke

---
 example/example_silksmoke.go | 26 +++++++++++++
 randcircle.go                | 12 +++---
 silksmoke.go                 | 75 ++++++++++++++++++++++++++++++++++++
 3 files changed, 107 insertions(+), 6 deletions(-)
 create mode 100644 example/example_silksmoke.go
 create mode 100644 silksmoke.go

diff --git a/example/example_silksmoke.go b/example/example_silksmoke.go
new file mode 100644
index 0000000..46edc02
--- /dev/null
+++ b/example/example_silksmoke.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.Black)
+	c.SetLineWidth(1.0)
+	c.SetLineColor(color.RGBA{
+		R: 255,
+		G: 255,
+		B: 255,
+		A: 30,
+	})
+	c.SetColorSchema(generativeart.Plasma)
+	c.SetIterations(4)
+	c.FillBackground()
+	c.Draw(generativeart.NewSilkSmoke(400, 20, 0.2, 2, 10, 30, false))
+	c.ToPNG("silksmoke.png")
+}
diff --git a/randcircle.go b/randcircle.go
index cb65278..9dfc627 100644
--- a/randcircle.go
+++ b/randcircle.go
@@ -34,15 +34,15 @@ func NewRandCicle(mc, msp int, minStep, maxStep, minr, maxr float64, isRandColor
 	}
 }
 
-func (r *randCircle) newCircleSlice(cn, w, h int) []circle {
+func newCircleSlice(cn, w, h int, minStep, maxStep, minRadius, maxRadius float64) []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
+		radius := float64(rand.Intn(int(minRadius))) + maxRadius - minRadius
 		angle := rand.Float64() * math.Pi * 2.0
-		step := r.minSteps + rand.Float64()*(r.maxSteps-r.minSteps)
+		step := minStep + rand.Float64()*(maxStep-minStep)
 		circles = append(circles, circle{
 			x:      float64(x),
 			y:      float64(y),
@@ -55,7 +55,7 @@ func (r *randCircle) newCircleSlice(cn, w, h int) []circle {
 	return circles
 }
 
-func (r *randCircle) circleSliceUpdate(cs []circle, w, h int) []circle {
+func circleSliceUpdate(cs []circle, w, h int) []circle {
 	var circles []circle
 
 	for _, c := range cs {
@@ -94,7 +94,7 @@ func (r *randCircle) Generative(c *canva) {
 
 	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)
+		circles := newCircleSlice(cn, c.width, c.height, r.minSteps, r.maxSteps, r.minRadius, r.maxRadius)
 
 		for i := 0; i < r.maxStepsPerCircle; i++ {
 			for _, c1 := range circles {
@@ -123,7 +123,7 @@ func (r *randCircle) Generative(c *canva) {
 				}
 			}
 
-			circles = r.circleSliceUpdate(circles, c.width, c.height)
+			circles = circleSliceUpdate(circles, c.width, c.height)
 		}
 	}
 }
diff --git a/silksmoke.go b/silksmoke.go
new file mode 100644
index 0000000..c13c0ba
--- /dev/null
+++ b/silksmoke.go
@@ -0,0 +1,75 @@
+package generativeart
+
+import (
+	"github.com/fogleman/gg"
+	"math/rand"
+)
+
+type sileSmoke struct {
+	maxCircle         int
+	maxStepsPerCircle int
+	minSteps          float64
+	maxSteps          float64
+	minRadius         float64
+	maxRadius         float64
+	isRandColor       bool
+}
+
+func NewSilkSmoke(mc, msp int, minStep, maxStep, minRadius, maxRadius float64, isRandColor bool) *sileSmoke {
+	return &sileSmoke{
+		maxCircle:         mc,
+		maxStepsPerCircle: msp,
+		minSteps:          minStep,
+		maxSteps:          maxStep,
+		minRadius:         minRadius,
+		maxRadius:         maxRadius,
+		isRandColor:       isRandColor,
+	}
+}
+
+// Generative draws a silk smoke image.
+func (s *sileSmoke) Generative(c *canva) {
+	ctex := gg.NewContextForRGBA(c.img)
+
+	cn := rand.Intn(s.maxCircle) + int(s.maxCircle/3)
+	circles := newCircleSlice(cn, c.width, c.height, s.minSteps, s.maxSteps, s.minRadius, s.maxRadius)
+
+	for i :=0; i<s.maxStepsPerCircle; i++ {
+		ctex.SetRGBA255(0, 0, 0, 5)
+		ctex.DrawRectangle(0, 0, float64(c.width), float64(c.height))
+		ctex.Fill()
+
+		for _, c1 := range circles {
+			for _, c2 := range circles {
+
+				cl := c.opts.lineColor
+				if s.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.LineTo(c1.x, c1.y)
+					ctex.LineTo(c2.x, c2.y)
+					ctex.LineTo(cx, cy)
+					ctex.LineTo(c1.x, c1.y)
+
+					ctex.Stroke()
+				}
+			}
+		}
+
+		circles = circleSliceUpdate(circles, c.width, c.height)
+	}
+}
\ No newline at end of file