Quantize each vertex only once.

src/pixie/paths.nim

@@ -1054,8 +1054,21 @@ proc commandsToShapes(
 
 proc shapesToSegments(shapes: seq[Polygon]): seq[(Segment, int16)] =
   ## Converts the shapes into a set of filtered segments with winding value.
-  for shape in shapes:
-    for segment in shape.segments:
+
+  # Quantize the segment to prevent leaks
+  template quantize(v: Vec2, q: float32): Vec2 =
+    vec2(v.x.quantize(q), v.y.quantize(q))
+
+  for poly in shapes:
+    var
+      vec1 = poly[^1].quantize(1 / 256)
+      vec2 = poly[0].quantize(1 / 256)
+      segment: Segment
+    for i in 0 ..< poly.len:
+      if i != 0:
+        vec2 = vec1
+        vec1 = poly[i].quantize(1 / 256)
+      segment = segment(vec1, vec2)
       if segment.at.y == segment.to.y: # Skip horizontal
         continue
       var
@@ -1065,12 +1078,6 @@ proc shapesToSegments(shapes: seq[Polygon]): seq[(Segment, int16)] =
         swap(segment.at, segment.to)
         winding = -1
 
-      # Quantize the segment to prevent leaks
-      segment = segment(
-        vec2(segment.at.x.quantize(1 / 256), segment.at.y.quantize(1 / 256)),
-        vec2(segment.to.x.quantize(1 / 256), segment.to.y.quantize(1 / 256))
-      )
-
       result.add((segment, winding))
 
 proc transform(shapes: var seq[Polygon], transform: Mat3) =