obj export improvements

hub/exports/formats/obj.py

@@ -4,9 +4,11 @@ SPDX - License - Identifier: LGPL - 3.0 - or -later
 Copyright © 2022 Concordia CERC group
 Project Coder Guille Gutierrez guillermo.gutierrezmorote@concordia.ca
 """
-
+import math
 from pathlib import Path
 
+import numpy as np
+
 
 class Obj:
   """
@@ -17,41 +19,80 @@ class Obj:
     self._path = path
     self._export()
 
-  def _to_vertex(self, coordinate):
+  def _ground(self, coordinate):
     x = coordinate[0] - self._city.lower_corner[0]
     y = coordinate[1] - self._city.lower_corner[1]
     z = coordinate[2] - self._city.lower_corner[2]
-    return f'v {x} {y} {z}\n'
+    return x, y, z
+
+  def _to_vertex(self, coordinate):
+    x, y, z = self._ground(coordinate)
+    return f'v {x} {z} {y}\n'
+
+  def _to_texture_vertex(self, coordinate):
+    u, v, _ = self._ground(coordinate)
+    return f'vt {u} {v}\n'
+
+  def _to_normal_vertex(self, coordinates):
+    ground_vertex = []
+    for coordinate in coordinates:
+      x, y, z = self._ground(coordinate)
+      ground_vertex.append(np.array([x, y, z]))
+    # recalculate the normal to get grounded values
+    edge_1 = ground_vertex[1] - ground_vertex[0]
+    edge_2 = ground_vertex[2] - ground_vertex[0]
+    normal = np.cross(edge_1, edge_2)
+    normal = normal / np.linalg.norm(normal)
+    return f'vn {normal[0]} {normal[1]} {normal[2]}\n'
 
   def _export(self):
     if self._city.name is None:
       self._city.name = 'unknown_city'
-    file_name = self._city.name + '.obj'
-    file_path = (Path(self._path).resolve() / file_name).resolve()
+    obj_name = f'{self._city.name}.obj'
+    mtl_name = f'{self._city.name}.mtl'
+    obj_file_path = (Path(self._path).resolve() / obj_name).resolve()
+    mtl_file_path = (Path(self._path).resolve() / mtl_name).resolve()
+    with open(mtl_file_path, 'w', encoding='utf-8') as mtl:
+      mtl.write("newmtl cerc_base_material\n")
+      mtl.write("Ka 1.0 1.0 1.0      # Ambient color (white)\n")
+      mtl.write("Kd 0.3 0.8 0.3      # Diffuse color (greenish)\n")
+      mtl.write("Ks 1.0 1.0 1.0      # Specular color (white)\n")
+      mtl.write("Ns 400.0             # Specular exponent (defines shininess)\n")
     vertices = {}
-    with open(file_path, 'w', encoding='utf-8') as obj:
+    normals_index = {}
+    faces = []
+    vertex_index = 0
+    normal_index = 0
+    with open(obj_file_path, 'w', encoding='utf-8') as obj:
       obj.write("# cerc-hub export\n")
-      vertex_index = 0
-      faces = []
+      obj.write(f'mtllib {mtl_name}')
+
       for building in self._city.buildings:
         obj.write(f'# building {building.name}\n')
         obj.write(f'g {building.name}\n')
         obj.write('s off\n')
         for surface in building.surfaces:
           obj.write(f'# surface {surface.name}\n')
-          face = 'f '
+          face = []
+          normal = self._to_normal_vertex(surface.perimeter_polygon.coordinates)
+          normal_index += 1
+          textures = []
           for coordinate in surface.perimeter_polygon.coordinates:
             vertex = self._to_vertex(coordinate)
+
             if vertex not in vertices:
               vertex_index += 1
               vertices[vertex] = vertex_index
               current = vertex_index
               obj.write(vertex)
+              textures.append(self._to_texture_vertex(coordinate))  # only append if non-existing
             else:
               current = vertices[vertex]
 
-            face = f'{face} {current}'
+            face.insert(0, f'{current}/{current}/{normal_index}')  # insert counterclockwise
+          obj.writelines(normal)  # add the normal
+          obj.writelines(textures)  # add the texture vertex
 
-          faces.append(f'{face} {face.split(" ")[1]}\n')
+          faces.append(f"f {' '.join(face)}\n")
           obj.writelines(faces)
           faces = []

tests/test_exports.py

@@ -66,12 +66,7 @@ class TestExports(TestCase):
 
   def _export(self, export_type, from_pickle=False):
     self._complete_city = self._get_complete_city(from_pickle)
-    try:
-      ExportsFactory(export_type, self._complete_city, self._output_path).export()
-    except ValueError as err:
-      if export_type != 'stl':
-        logging.warning('No backend export for STL test, skipped')
-        raise err
+    ExportsFactory(export_type, self._complete_city, self._output_path).export()
 
   def _export_building_energy(self, export_type, from_pickle=False):
       self._complete_city = self._get_complete_city(from_pickle)
@@ -83,12 +78,6 @@ class TestExports(TestCase):
     """
     self._export('obj', False)
 
-  def test_stl_export(self):
-    """
-    export to stl
-    """
-    self._export('stl', False)
-
   def test_energy_ade_export(self):
     """
     export to energy ADE