From 7f2aa95f6732fe32b91597394675ec6cc0197725 Mon Sep 17 00:00:00 2001
From: Michael Dawson-Haggerty <mikedh@kerfed.com>
Date: Fri, 19 Jul 2024 12:38:28 -0400
Subject: [PATCH] add an early exit for polygon creation

---
 trimesh/base.py               |  2 +-
 trimesh/convex.py             |  2 +-
 trimesh/path/exchange/misc.py |  1 +
 trimesh/path/polygons.py      | 17 ++++++++++++++---
 trimesh/triangles.py          | 27 ++++++++++++++++-----------
 5 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/trimesh/base.py b/trimesh/base.py
index aafec90e6..082007317 100644
--- a/trimesh/base.py
+++ b/trimesh/base.py
@@ -2667,7 +2667,7 @@ def area_faces(self) -> NDArray[float64]:
         area_faces : (n, ) float
           Area of each face
         """
-        return triangles.area(crosses=self.triangles_cross, sum=False)
+        return triangles.area(crosses=self.triangles_cross)
 
     @caching.cache_decorator
     def mass_properties(self) -> MassProperties:
diff --git a/trimesh/convex.py b/trimesh/convex.py
index 396589e73..3e507b4cb 100644
--- a/trimesh/convex.py
+++ b/trimesh/convex.py
@@ -91,7 +91,7 @@ def convex_hull(obj, qhull_options="QbB Pp Qt", repair=True):
     crosses = crosses[valid]
 
     # each triangle area and mean center
-    triangles_area = triangles.area(crosses=crosses, sum=False)
+    triangles_area = triangles.area(crosses=crosses)
     triangles_center = vertices[faces].mean(axis=1)
 
     # since the convex hull is (hopefully) convex, the vector from
diff --git a/trimesh/path/exchange/misc.py b/trimesh/path/exchange/misc.py
index d035244d4..de76fdcd0 100644
--- a/trimesh/path/exchange/misc.py
+++ b/trimesh/path/exchange/misc.py
@@ -111,6 +111,7 @@ def polygon_to_path(polygon):
         "entities": entities,
         "vertices": np.vstack(vertices) if len(vertices) > 0 else vertices,
     }
+
     return kwargs
 
 
diff --git a/trimesh/path/polygons.py b/trimesh/path/polygons.py
index dda5af7a6..c2d8edf42 100644
--- a/trimesh/path/polygons.py
+++ b/trimesh/path/polygons.py
@@ -50,6 +50,14 @@ def enclosure_tree(polygons):
        contained by another polygon
     """
 
+    # nodes are indexes in polygons
+    contains = nx.DiGraph()
+
+    if len(polygons) == 1:
+        # add an early exit for only a single polygon
+        contains.add_node(0)
+        return np.array([0], dtype=np.int64), contains
+
     # get the bounds for every valid polygon
     bounds = {
         k: v
@@ -59,8 +67,6 @@ def enclosure_tree(polygons):
         if len(v) == 4
     }
 
-    # nodes are indexes in polygons
-    contains = nx.DiGraph()
     # make sure we don't have orphaned polygon
     contains.add_nodes_from(bounds.keys())
 
@@ -551,13 +557,18 @@ def paths_to_polygons(paths, scale=None):
             # non-zero area
             continue
         try:
-            polygons[i] = repair_invalid(Polygon(path), scale)
+            polygon = Polygon(path)
+            if polygon.is_valid:
+                polygons[i] = polygon
+            else:
+                polygons[i] = repair_invalid(polygon, scale)
         except ValueError:
             # raised if a polygon is unrecoverable
             continue
         except BaseException:
             log.error("unrecoverable polygon", exc_info=True)
     polygons = np.array(polygons)
+
     return polygons
 
 
diff --git a/trimesh/triangles.py b/trimesh/triangles.py
index 7af0513b6..b6efa3285 100644
--- a/trimesh/triangles.py
+++ b/trimesh/triangles.py
@@ -16,7 +16,7 @@
 from .util import diagonal_dot, unitize
 
 
-def cross(triangles):
+def cross(triangles: NDArray) -> NDArray:
     """
     Returns the cross product of two edges from input triangles
 
@@ -30,13 +30,19 @@ def cross(triangles):
     crosses : (n, 3) float
       Cross product of two edge vectors
     """
-    vectors = np.diff(triangles, axis=1)
-    crosses = np.cross(vectors[:, 0], vectors[:, 1])
+    vectors = triangles[:, 1:, :] - triangles[:, :2, :]
+    if triangles.shape[2] == 3:
+        return np.cross(vectors[:, 0], vectors[:, 1])
+    elif triangles.shape[2] == 2:
+        a = vectors[:, 0]
+        b = vectors[:, 1]
+        # numpy 2.0 deprecated 2D cross productes
+        return a[:, 0] * b[:, 1] - a[:, 1] * b[:, 0]
 
-    return crosses
+    raise ValueError(triangles.shape)
 
 
-def area(triangles=None, crosses=None, sum=False):
+def area(triangles=None, crosses=None):
     """
     Calculates the sum area of input triangles
 
@@ -55,11 +61,8 @@ def area(triangles=None, crosses=None, sum=False):
       Individual or summed area depending on `sum` argument
     """
     if crosses is None:
-        crosses = cross(triangles)
-    areas = np.sqrt((crosses**2).sum(axis=1)) / 2.0
-    if sum:
-        return areas.sum()
-    return areas
+        crosses = cross(np.asanyarray(triangles, dtype=np.float64))
+    return np.sqrt((crosses**2).sum(axis=1)) / 2.0
 
 
 def normals(triangles=None, crosses=None):
@@ -80,6 +83,8 @@ def normals(triangles=None, crosses=None):
     valid : (n,) bool
       Was the face nonzero area or not
     """
+    if triangles is not None and triangles.shape[-1] == 2:
+        return np.tile([0.0, 0.0, 1.0], (triangles.shape[0], 1))
     if crosses is None:
         crosses = cross(triangles)
     # unitize the cross product vectors
@@ -435,7 +440,7 @@ def extents(triangles, areas=None):
         raise ValueError("Triangles must be (n, 3, 3)!")
 
     if areas is None:
-        areas = area(triangles=triangles, sum=False)
+        areas = area(triangles=triangles)
 
     # the edge vectors which define the triangle
     a = triangles[:, 1] - triangles[:, 0]