feat: support passing a seed in for reproducibility

main.go

@@ -28,6 +28,7 @@ var (
 	Workers    int
 	Nth        int
 	Repeat     int
+	Seed       int64
 	V, VV      bool
 )
 
@@ -73,6 +74,10 @@ func init() {
 	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")
+	flag.Func("seed", "seed to feed the RNG", func(value string) (err error) {
+		Seed, err = strconv.ParseInt(value, 10, 64)
+		return
+	})
 	flag.BoolVar(&V, "v", false, "verbose")
 	flag.BoolVar(&VV, "vv", false, "very verbose")
 }
@@ -126,7 +131,10 @@ func main() {
 	}
 
 	// seed random number generator
-	rand.Seed(time.Now().UTC().UnixNano())
+	if Seed == 0 {
+		Seed = time.Now().UTC().UnixNano()
+	}
+	rand.Seed(Seed)
 
 	// determine worker count
 	if Workers < 1 {
@@ -153,7 +161,7 @@ func main() {
 	}
 
 	// run algorithm
-	model := primitive.NewModel(input, bg, OutputSize, Workers)
+	model := primitive.NewModel(input, bg, OutputSize, Workers, Seed+1)
 	primitive.Log(1, "%d: t=%.3f, score=%.6f\n", 0, 0.0, model.Score)
 	start := time.Now()
 	frame := 0

primitive/model.go

@@ -22,7 +22,7 @@ type Model struct {
 	Workers    []*Worker
 }
 
-func NewModel(target image.Image, background Color, size, numWorkers int) *Model {
+func NewModel(target image.Image, background Color, size, numWorkers int, seed int64) *Model {
 	w := target.Bounds().Size().X
 	h := target.Bounds().Size().Y
 	aspect := float64(w) / float64(h)
@@ -48,7 +48,7 @@ func NewModel(target image.Image, background Color, size, numWorkers int) *Model
 	model.Score = differenceFull(model.Target, model.Current)
 	model.Context = model.newContext()
 	for i := 0; i < numWorkers; i++ {
-		worker := NewWorker(model.Target)
+		worker := NewWorker(model.Target, seed)
 		model.Workers = append(model.Workers, worker)
 	}
 	return model

primitive/raster.go

@@ -10,7 +10,7 @@ func fix(x float64) fixed.Int26_6 {
 }
 
 func fixp(x, y float64) fixed.Point26_6 {
-	return fixed.Point26_6{fix(x), fix(y)}
+	return fixed.Point26_6{X: fix(x), Y: fix(y)}
 }
 
 type painter struct {

primitive/util.go

@@ -61,7 +61,7 @@ func SaveJPG(path string, im image.Image, quality int) error {
 		return err
 	}
 	defer file.Close()
-	return jpeg.Encode(file, im, &jpeg.Options{quality})
+	return jpeg.Encode(file, im, &jpeg.Options{Quality: quality})
 }
 
 func SaveGIF(path string, frames []image.Image, delay, lastDelay int) error {

primitive/worker.go

@@ -3,7 +3,6 @@ package primitive
 import (
 	"image"
 	"math/rand"
-	"time"
 
 	"github.com/golang/freetype/raster"
 )
@@ -21,7 +20,7 @@ type Worker struct {
 	Counter    int
 }
 
-func NewWorker(target *image.RGBA) *Worker {
+func NewWorker(target *image.RGBA, seed int64) *Worker {
 	w := target.Bounds().Size().X
 	h := target.Bounds().Size().Y
 	worker := Worker{}
@@ -32,7 +31,7 @@ func NewWorker(target *image.RGBA) *Worker {
 	worker.Rasterizer = raster.NewRasterizer(w, h)
 	worker.Lines = make([]Scanline, 0, 4096) // TODO: based on height
 	worker.Heatmap = NewHeatmap(w, h)
-	worker.Rnd = rand.New(rand.NewSource(time.Now().UnixNano()))
+	worker.Rnd = rand.New(rand.NewSource(seed))
 	return &worker
 }