Fixed problem with map.

Map wasn't detecting duplicate X,Y values.  It is now.

starfield.go

@@ -11,8 +11,11 @@ import (
 )
 
 type StarPos struct {
-	Y      int
-	X      int
+	Y int
+	X int
+}
+
+type StarInfo struct {
 	Symbol int
 	Color  bool
 }
@@ -21,7 +24,7 @@ type StarField struct {
 	RNG *rand.Rand
 	MX  int
 	MY  int
-	Sky map[StarPos]struct{}
+	Sky map[StarPos]StarInfo
 }
 
 func (s *StarField) make_pos() StarPos {
@@ -37,17 +40,17 @@ func (s *StarField) make_pos() StarPos {
 func (s *StarField) Regenerate() {
 	s.MX = door.Width
 	s.MY = door.Height
-	s.Sky = make(map[StarPos]struct{})
 
 	s.RNG = rand.New(mt19937.New())
 	s.RNG.Seed(time.Now().UnixNano())
 
 	max_stars := ((s.MX * s.MY) / 40)
+	s.Sky = make(map[StarPos]StarInfo, max_stars)
+
 	for i := 0; i < max_stars; i++ {
 		pos := s.make_pos()
-		pos.Symbol = i % 2
-		pos.Color = i%5 < 2
-		s.Sky[pos] = struct{}{}
+		info := StarInfo{Symbol: i % 2, Color: i%5 < 2}
+		s.Sky[pos] = info
 	}
 }
 
@@ -68,7 +71,7 @@ func (s *StarField) Display(d *door.Door) {
 	var last_pos StarPos
 
 	// maps in go are not sorted
-	for pos, _ := range s.Sky {
+	for pos, info := range s.Sky {
 		use_goto := true
 
 		if i != 0 {
@@ -104,12 +107,12 @@ func (s *StarField) Display(d *door.Door) {
 			d.Write(door.Goto(pos.X, pos.Y))
 		}
 
-		if pos.Color {
+		if info.Color {
 			d.Write(dark)
 		} else {
 			d.Write(white)
 		}
-		d.Write(stars[pos.Symbol])
+		d.Write(stars[info.Symbol])
 		last_pos = pos
 		last_pos.X++
 		i++