3D: a profile's empty contours count toward its point limit

revolve_curve_samples counted a profile's contours but never compared the count with the limit,
so a profile made only of empty or one-anchor subpaths passed, although each contour takes one
profile point. HoleSearch::new then built one entry for each subpath without a limit, and mesh
export skips revolve_curve_samples when curve_samples is given. Both now refuse a profile with
more than 16,384 contours as too complex.

crates/three-d/src/lib.rs

@@ -480,10 +480,10 @@ pub fn revolve_curve_samples<'a>(paths: impl IntoIterator<Item = &'a PathData>,
     let (mut anchors, mut contours, mut lines, mut curves, mut caps) = (0usize, 0usize, 0usize, 0usize, 0usize);
     for sp in paths.into_iter().flat_map(|p| &p.subpaths) {
         anchors = anchors.saturating_add(sp.anchors.len());
-        if anchors > MAX_PROFILE_POINTS {
+        contours += 1;
+        if anchors > MAX_PROFILE_POINTS || contours > MAX_PROFILE_POINTS {
             return Err(TOO_COMPLEX_PROFILE.into());
         }
-        contours += 1;
         let segments = if sp.closed { sp.anchors.len() } else { sp.anchors.len().saturating_sub(1) };
         for i in 0..segments {
             if sp.segment_is_line(i) {
@@ -551,6 +551,10 @@ struct HoleSearch {
 
 impl HoleSearch {
     fn new(path: &PathData, rule: FillRule) -> Result<Self, String> {
+        // Each contour takes a profile point, as in `revolve_curve_samples`.
+        if path.subpaths.len() > MAX_PROFILE_POINTS {
+            return Err(TOO_COMPLEX_PROFILE.into());
+        }
         let contours: Vec<(BezPath, Rect, Option<i32>)> = path
             .subpaths
             .iter()

crates/three-d/src/tests/profile_limits.rs

@@ -68,6 +68,17 @@ fn too_many_anchors_are_refused_as_a_profile() {
     assert_eq!(refused, TOO_COMPLEX_PROFILE);
 }
 
+#[test]
+fn every_contour_takes_a_point_even_an_empty_one() {
+    // Contours of one anchor and of none, with no segment between them.
+    let lone = |i: usize| SubPath::new(if i.is_multiple_of(2) { vec![] } else { vec![Anchor::corner(Point::new(100.0, i as f64))] }, false);
+    let path = PathData::new((0..=MAX_PROFILE_POINTS).map(lone).collect());
+    assert_eq!(revolve_curve_samples([&path], Revolve::default()), Err(TOO_COMPLEX_PROFILE.to_string()));
+    assert_eq!(hole_segments(&path, FillRule::NonZero), Err(TOO_COMPLEX_PROFILE.to_string()), "before any contour is built");
+    let given = Revolve { curve_samples: Some(CURVE_SAMPLES), ..Revolve::default() };
+    assert_eq!(revolve_mesh(&path, FillRule::NonZero, path.bounds().unwrap(), given).map(|_| ()), Err(TOO_COMPLEX_PROFILE.to_string()));
+}
+
 #[test]
 fn a_profile_at_the_point_limit_is_taken_and_one_past_it_is_refused() {
     let straight = |anchors: usize| {