First test at implementing chords

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)
+}