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