modified triangulation method

hub/city_model_structure/attributes/polygon.py

@@ -9,6 +9,7 @@ from __future__ import annotations
 import math
 import sys
 from typing import List
+from hub.hub_logger import logger
 import numpy as np
 from trimesh import Trimesh
 import trimesh.intersections
@@ -242,24 +243,32 @@ class Polygon:
 
     polygon = shapley_polygon(coordinates)
 
-    vertices_2d, faces = trimesh.creation.triangulate_polygon(polygon, engine='triangle')
-    mesh = Trimesh(vertices=vertices, faces=faces)
+    try:
+      vertices_2d, faces = trimesh.creation.triangulate_polygon(polygon, engine='triangle')
+      mesh = Trimesh(vertices=vertices, faces=faces)
 
-    # check orientation
-    normal_sum = 0
-    for i in range(0, 3):
-      normal_sum += normal[i] + mesh.face_normals[0][i]
+      # check orientation
+      normal_sum = 0
+      for i in range(0, 3):
+        normal_sum += normal[i] + mesh.face_normals[0][i]
 
-    if abs(normal_sum) <= 1E-10:
-      new_faces = []
-      for face in faces:
-        new_face = []
-        for i in range(0, len(face)):
-          new_face.append(face[len(face)-i-1])
-        new_faces.append(new_face)
-      mesh = Trimesh(vertices=vertices, faces=new_faces)
+      if abs(normal_sum) <= 1E-10:
+        new_faces = []
+        for face in faces:
+          new_face = []
+          for i in range(0, len(face)):
+            new_face.append(face[len(face)-i-1])
+          new_faces.append(new_face)
+        mesh = Trimesh(vertices=vertices, faces=new_faces)
 
-    return mesh
+      return mesh
+
+    except ValueError:
+      logger.error(f'Not able to triangulate polygon\n')
+      sys.stderr.write(f'Not able to triangulate polygon\n')
+      _vertices = [[0, 0, 0], [0, 0, 1], [0, 1, 0]]
+      _faces = [[0, 1, 2]]
+      return Trimesh(vertices=_vertices, faces=_faces)
 
   @property
   def triangles(self) -> List[Polygon]: