import glob
import json
import os
import pathlib
import random
import bpy
from blenderproc.python.types.MeshObjectUtility import MeshObject
from blenderproc.python.utility.Utility import resolve_path
from blenderproc.python.loader.ObjectLoader import load_obj
[docs]def load_shapenet(data_path: str, used_synset_id: str, used_source_id: str = "", move_object_origin: bool = True) -> MeshObject:
""" This loads an object from ShapeNet based on the given synset_id, which specifies the category of objects to use.
From these objects one is randomly sampled and loaded.
Todo: not good:
Note: if this module is used with another loader that loads objects with semantic mapping, make sure the other module is loaded first in the config file.
:param data_path: The path to the ShapeNetCore.v2 folder.
:param used_synset_id: The synset id for example: '02691156', check the data_path folder for more ids.
:param used_source_id: Object identifier of the a particular ShapeNet category, see inside any ShapeNet category for identifiers
:param move_object_origin: Moves the object center to the bottom of the bounding box in Z direction and also in the middle of the X and Y plane, this does not change the `.location` of the object. Default: True
:return: The loaded mesh object.
"""
data_path = resolve_path(data_path)
taxonomy_file_path = os.path.join(data_path, "taxonomy.json")
files_with_fitting_synset = ShapeNetLoader._get_files_with_synset(used_synset_id, used_source_id, taxonomy_file_path, data_path)
selected_obj = random.choice(files_with_fitting_synset)
loaded_objects = load_obj(selected_obj)
# In shapenet every .obj file only contains one object, make sure that is the case
if len(loaded_objects) != 1:
raise Exception("The ShapeNetLoader expects every .obj file to contain exactly one object, however the file " + selected_obj + " contained " + str(len(loaded_objects)) + " objects.")
obj = loaded_objects[0]
obj.set_cp("used_synset_id", used_synset_id)
obj.set_cp("used_source_id", pathlib.PurePath(selected_obj).parts[-3])
ShapeNetLoader._correct_materials(obj)
# removes the x axis rotation found in all ShapeNet objects, this is caused by importing .obj files
# the object has the same pose as before, just that the rotation_euler is now [0, 0, 0]
obj.persist_transformation_into_mesh(location=False, rotation=True, scale=False)
# check if the move_to_world_origin flag is set
if move_object_origin:
# move the origin of the object to the world origin and on top of the X-Y plane
# makes it easier to place them later on, this does not change the `.location`
obj.move_origin_to_bottom_mean_point()
bpy.ops.object.select_all(action='DESELECT')
return obj
[docs]class ShapeNetLoader:
[docs] @staticmethod
def _get_files_with_synset(used_synset_id: str, used_source_id: str, path_to_taxonomy_file: str, data_path: str) -> list:
""" Returns a list of a .obj file for the given synset_id
:param used_synset_id: the id of the category something like: '02691156', see the data_path folder for more ids
:param used_source_id: object identifier of the a particular ShapeNet category, see inside any ShapeNet category for identifiers
:param path_to_taxonomy_file: path to the taxonomy.json file, should be in the data_path, too
:param data_path: path to the ShapeNetCore.v2 folder
:return: list of .obj files, which are in the synset_id folder, based on the given taxonomy
"""
if os.path.exists(path_to_taxonomy_file):
files = []
with open(path_to_taxonomy_file, "r") as f:
loaded_data = json.load(f)
parent_synset_id = ShapeNetLoader.find_parent_synset_id(data_path, used_synset_id, loaded_data)
id_path = os.path.join(data_path, parent_synset_id)
if not used_source_id:
files.extend(glob.glob(os.path.join(id_path, "*", "models", "model_normalized.obj")))
else:
if not os.path.exists(os.path.join(id_path, used_source_id)):
raise Exception("The used_source_id {} is not correct".format(used_source_id))
# Using both the used_synset_id and used_source_id
files.append(os.path.join(id_path, used_source_id, "models", "model_normalized.obj"))
# Sort files to make random choice deterministic for the case when used_source_id is not specified
files.sort()
return files
else:
raise Exception("The taxonomy file could not be found: {}".format(path_to_taxonomy_file))
[docs] @staticmethod
def find_parent_synset_id(data_path, synset_id, json_data):
"""
Returns the parent synset_id if it exists. If the synset_id is already parent synset_id, it is just returned
:param data_path: path to the ShapeNetCore.v2 folder
:param synset_id: the id of the category something like: '02691156', see the data_path folder for more ids
:param json_data: loaded data from the ShapeNet taxonomy.json file
:return: parent synset_id
"""
id_path = os.path.join(data_path, synset_id)
# Check if the synset_id is alreay a parent synset_id
if os.path.exists(id_path):
return synset_id
for block in json_data:
if synset_id in block["children"]:
parent_synset_id = block["synsetId"]
return ShapeNetLoader.find_parent_synset_id(data_path, parent_synset_id, json_data)
raise Exception("The used_synset_id {} does not exists in the taxonomy file".format(synset_id))
[docs] @staticmethod
def _correct_materials(obj: MeshObject):
""" If the used material contains an alpha texture, the alpha texture has to be flipped to be correct
:param obj: object where the material maybe wrong
"""
for material in obj.get_materials():
if material is None:
continue
texture_nodes = material.get_nodes_with_type("ShaderNodeTexImage")
if texture_nodes and len(texture_nodes) > 1:
principled_bsdf = material.get_the_one_node_with_type("BsdfPrincipled")
# find the image texture node which is connect to alpha
node_connected_to_the_alpha = None
for node_links in principled_bsdf.inputs["Alpha"].links:
if "ShaderNodeTexImage" in node_links.from_node.bl_idname:
node_connected_to_the_alpha = node_links.from_node
# if a node was found which is connected to the alpha node, add an invert between the two
if node_connected_to_the_alpha is not None:
invert_node = material.new_node("ShaderNodeInvert")
invert_node.inputs["Fac"].default_value = 1.0
material.insert_node_instead_existing_link(node_connected_to_the_alpha.outputs["Color"],
invert_node.inputs["Color"],
invert_node.outputs["Color"],
principled_bsdf.inputs["Alpha"])