First test at implementing chords

main.go

@@ -69,7 +69,7 @@ func init() {
 	flag.IntVar(&Alpha, "a", 128, "alpha value")
 	flag.IntVar(&InputSize, "r", 256, "resize large input images to this size")
 	flag.IntVar(&OutputSize, "s", 1024, "output image size")
-	flag.IntVar(&Mode, "m", 1, "0=combo 1=triangle 2=rect 3=ellipse 4=circle 5=rotatedrect 6=beziers 7=rotatedellipse 8=polygon")
+	flag.IntVar(&Mode, "m", 1, "0=combo 1=triangle 2=rect 3=ellipse 4=circle 5=rotatedrect 6=beziers 7=rotatedellipse 8=polygon 9=chord")
 	flag.IntVar(&Workers, "j", 0, "number of parallel workers (default uses all cores)")
 	flag.IntVar(&Nth, "nth", 1, "save every Nth frame (put \"%d\" in path)")
 	flag.IntVar(&Repeat, "rep", 0, "add N extra shapes per iteration with reduced search")

primitive/chord.go

@@ -0,0 +1,102 @@
+package primitive
+
+import (
+	"fmt"
+	"strings"
+	"math"
+
+	"github.com/fogleman/gg"
+	"github.com/golang/freetype/raster"
+)
+
+type Chord struct {
+	Worker *Worker
+	A1, A2 float64
+	//X1, Y1 float64
+	//X2, Y2 float64
+}
+
+func NewRandomChord(worker *Worker) *Chord {
+	rnd := worker.Rnd
+
+	// These will be on (-1, 1)
+	a1 := rnd.Float64() * float64(360)
+	a2 := rnd.Float64() * float64(360)
+
+	q := &Chord{worker, a1, a2}
+	q.Mutate()
+	return q
+}
+
+func (q *Chord) GetPositions() (float64, float64, float64, float64) {
+	// So we need to make them on a unit circle centered around worker.W / 2, worker.H / 2
+	// Of width worker.W / 2 and height worker.H / 2
+	half_width := float64(q.Worker.W) / 2
+	half_height:= float64(q.Worker.H) / 2
+
+	x1 := math.Cos(q.A1)
+	y1 := math.Sin(q.A1)
+	x2 := math.Cos(q.A2)
+	y2 := math.Sin(q.A2)
+
+	x1 = (x1 * half_width) + half_width
+	y1 = (y1 * half_height) + half_height
+	x2 = (x2 * half_width) + half_width
+	y2 = (y2 * half_height) + half_height
+	return x1, y1, x2, y2
+}
+
+func (q *Chord) Draw(dc *gg.Context, scale float64) {
+	x1, y1, x2, y2 := q.GetPositions()
+
+	dc.MoveTo(x1, y1)
+	dc.MoveTo(x2, y2)
+	dc.SetLineWidth(1)
+	dc.Stroke()
+}
+
+func (q *Chord) SVG(attrs string) string {
+	// TODO: this is a little silly
+	x1, y1, x2, y2 := q.GetPositions()
+	attrs = strings.Replace(attrs, "fill", "stroke", -1)
+	return fmt.Sprintf(
+		"<line %s x1=\"%f\" y1=\"%f\" x2=\"%f\" y2=\"%f\" stroke-width=\"1\" />",
+		attrs, x1, y1, x2, y2)
+}
+
+func (q *Chord) Copy() Shape {
+	a := *q
+	return &a
+}
+
+func (q *Chord) Mutate() {
+	const m = 16
+	rnd := q.Worker.Rnd
+	for {
+		switch rnd.Intn(2) {
+		case 0:
+			q.A1 = clamp(q.A1 + rnd.NormFloat64() * m, 0, 360)
+		case 1:
+			q.A2 = clamp(q.A2 + rnd.NormFloat64() * m, 0, 360)
+		}
+		if q.Valid() {
+			break
+		}
+	}
+}
+
+func (q *Chord) Valid() bool {
+	return true;
+}
+
+func (q *Chord) Rasterize() []Scanline {
+	x1, y1, x2, y2 := q.GetPositions()
+
+	var path raster.Path
+	p1 := fixp(x1, y1)
+	p2 := fixp(x2, y2)
+	path.Start(p1)
+	path.Add1(p2)
+	width := fix(1)
+	return strokePath(q.Worker, path, width, raster.RoundCapper, raster.RoundJoiner)
+}

primitive/shape.go

@@ -22,4 +22,5 @@ const (
 	ShapeTypeQuadratic
 	ShapeTypeRotatedEllipse
 	ShapeTypePolygon
+	ShapeTypeChord
 )

primitive/worker.go

@@ -104,5 +104,7 @@ func (worker *Worker) RandomState(t ShapeType, a int) *State {
 		return NewState(worker, NewRandomRotatedEllipse(worker), a)
 	case ShapeTypePolygon:
 		return NewState(worker, NewRandomPolygon(worker, 4, false), a)
+	case ShapeTypeChord:
+		return NewState(worker, NewRandomChord(worker), a)
 	}
 }