# Copyright (c) 2018-2023, NVIDIA Corporation
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"""
This script reads an fbx file and returns the joint names, parents, and transforms.
NOTE: It requires the Python FBX package to be installed.
"""
import sys
import numpy as np
try:
import fbx
import FbxCommon
except ImportError as e:
print(
"Error: FBX library failed to load - importing FBX data will not succeed. Message: {}".format(
e
)
)
print("FBX Python SDK must be installed")
[docs]def fbx_to_npy(file_name_in, root_joint_name, fps):
"""
This function reads in an fbx file, and saves the relevant info to a numpy array
Fbx files have a series of animation curves, each of which has animations at different
times. This script assumes that for mocap data, there is only one animation curve that
contains all the joints. Otherwise it is unclear how to read in the data.
If this condition isn't met, then the method throws an error
:param file_name_in: str, file path in. Should be .fbx file
:return: nothing, it just writes a file.
"""
# Create the fbx scene object and load the .fbx file
fbx_sdk_manager, fbx_scene = FbxCommon.InitializeSdkObjects()
FbxCommon.LoadScene(fbx_sdk_manager, fbx_scene, file_name_in)
"""
To read in the animation, we must find the root node of the skeleton.
Unfortunately fbx files can have "scene parents" and other parts of the tree that are
not joints
As a crude fix, this reader just takes and finds the first thing which has an
animation curve attached
"""
search_root = root_joint_name is None or root_joint_name == ""
# Get the root node of the skeleton, which is the child of the scene's root node
possible_root_nodes = [fbx_scene.GetRootNode()]
found_root_node = False
max_key_count = 0
root_joint = None
while len(possible_root_nodes) > 0:
joint = possible_root_nodes.pop(0)
if not search_root:
if joint.GetName() == root_joint_name:
root_joint = joint
try:
curve = _get_animation_curve(joint, fbx_scene)
except RuntimeError:
curve = None
if curve is not None:
key_count = curve.KeyGetCount()
if key_count > max_key_count:
found_root_node = True
max_key_count = key_count
root_curve = curve
if search_root and not root_joint:
root_joint = joint
for child_index in range(joint.GetChildCount()):
possible_root_nodes.append(joint.GetChild(child_index))
if not found_root_node:
raise RuntimeError("No root joint found!! Exiting")
joint_list, joint_names, parents = _get_skeleton(root_joint)
"""
Read in the transformation matrices of the animation, taking the scaling into account
"""
anim_range, frame_count, frame_rate = _get_frame_count(fbx_scene)
local_transforms = []
# for frame in range(frame_count):
time_sec = anim_range.GetStart().GetSecondDouble()
time_range_sec = anim_range.GetStop().GetSecondDouble() - time_sec
fbx_fps = frame_count / time_range_sec
if fps != 120:
fbx_fps = fps
print("FPS: ", fbx_fps)
while time_sec < anim_range.GetStop().GetSecondDouble():
fbx_time = fbx.FbxTime()
fbx_time.SetSecondDouble(time_sec)
fbx_time = fbx_time.GetFramedTime()
transforms_current_frame = []
# Fbx has a unique time object which you need
# fbx_time = root_curve.KeyGetTime(frame)
for joint in joint_list:
arr = np.array(_recursive_to_list(joint.EvaluateLocalTransform(fbx_time)))
scales = np.array(_recursive_to_list(joint.EvaluateLocalScaling(fbx_time)))
if not np.allclose(scales[0:3], scales[0]):
raise ValueError(
"Different X, Y and Z scaling. Unsure how this should be handled. "
"To solve this, look at this link and try to upgrade the script "
"http://help.autodesk.com/view/FBX/2017/ENU/?guid=__files_GUID_10CDD"
"63C_79C1_4F2D_BB28_AD2BE65A02ED_htm"
)
# Adjust the array for scaling
arr /= scales[0]
arr[3, 3] = 1.0
transforms_current_frame.append(arr)
local_transforms.append(transforms_current_frame)
time_sec += 1.0 / fbx_fps
local_transforms = np.array(local_transforms)
print("Frame Count: ", len(local_transforms))
return joint_names, parents, local_transforms, fbx_fps
def _get_frame_count(fbx_scene):
# Get the animation stacks and layers, in order to pull off animation curves later
num_anim_stacks = fbx_scene.GetSrcObjectCount(
FbxCommon.FbxCriteria.ObjectType(FbxCommon.FbxAnimStack.ClassId)
)
# if num_anim_stacks != 1:
# raise RuntimeError(
# "More than one animation stack was found. "
# "This script must be modified to handle this case. Exiting"
# )
if num_anim_stacks > 1:
index = 1
else:
index = 0
anim_stack = fbx_scene.GetSrcObject(
FbxCommon.FbxCriteria.ObjectType(FbxCommon.FbxAnimStack.ClassId), index
)
anim_range = anim_stack.GetLocalTimeSpan()
duration = anim_range.GetDuration()
fps = duration.GetFrameRate(duration.GetGlobalTimeMode())
frame_count = duration.GetFrameCount(True)
return anim_range, frame_count, fps
def _get_animation_curve(joint, fbx_scene):
# Get the animation stacks and layers, in order to pull off animation curves later
num_anim_stacks = fbx_scene.GetSrcObjectCount(
FbxCommon.FbxCriteria.ObjectType(FbxCommon.FbxAnimStack.ClassId)
)
# if num_anim_stacks != 1:
# raise RuntimeError(
# "More than one animation stack was found. "
# "This script must be modified to handle this case. Exiting"
# )
if num_anim_stacks > 1:
index = 1
else:
index = 0
anim_stack = fbx_scene.GetSrcObject(
FbxCommon.FbxCriteria.ObjectType(FbxCommon.FbxAnimStack.ClassId), index
)
num_anim_layers = anim_stack.GetSrcObjectCount(
FbxCommon.FbxCriteria.ObjectType(FbxCommon.FbxAnimLayer.ClassId)
)
if num_anim_layers != 1:
raise RuntimeError(
"More than one animation layer was found. "
"This script must be modified to handle this case. Exiting"
)
animation_layer = anim_stack.GetSrcObject(
FbxCommon.FbxCriteria.ObjectType(FbxCommon.FbxAnimLayer.ClassId), 0
)
def _check_longest_curve(curve, max_curve_key_count):
longest_curve = None
if curve and curve.KeyGetCount() > max_curve_key_count[0]:
max_curve_key_count[0] = curve.KeyGetCount()
return True
return False
max_curve_key_count = [0]
longest_curve = None
for c in ["X", "Y", "Z"]:
curve = joint.LclTranslation.GetCurve(
animation_layer, c
) # sample curve for translation
if _check_longest_curve(curve, max_curve_key_count):
longest_curve = curve
curve = joint.LclRotation.GetCurve(animation_layer, "X")
if _check_longest_curve(curve, max_curve_key_count):
longest_curve = curve
return longest_curve
def _get_skeleton(root_joint):
# Do a depth first search of the skeleton to extract all the joints
joint_list = [root_joint]
joint_names = [root_joint.GetName()]
parents = [-1] # -1 means no parent
def append_children(joint, pos):
"""
Depth first search function
:param joint: joint item in the fbx
:param pos: position of current element (for parenting)
:return: Nothing
"""
for child_index in range(joint.GetChildCount()):
child = joint.GetChild(child_index)
joint_list.append(child)
joint_names.append(child.GetName())
parents.append(pos)
append_children(child, len(parents) - 1)
append_children(root_joint, 0)
return joint_list, joint_names, parents
def _recursive_to_list(array):
"""
Takes some iterable that might contain iterables and converts it to a list of lists
[of lists... etc]
Mainly used for converting the strange fbx wrappers for c++ arrays into python lists
:param array: array to be converted
:return: array converted to lists
"""
try:
return float(array)
except TypeError:
return [_recursive_to_list(a) for a in array]
[docs]def parse_fbx(file_name_in, root_joint_name, fps):
return fbx_to_npy(file_name_in, root_joint_name, fps)
