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blender-armature-to-json.py
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blender-armature-to-json.py
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# Print all of the actions for the active armature to stdout as JSON
bl_info = {
"name": "Export Armature to JSON",
"category": "Import-Export",
"blender": (2, 80, 0)
}
import bpy
import math
import mathutils
import json
class ExportArmatureToJSON(bpy.types.Operator):
"""Given an active armature, export it's actions and keyframed bone pose information to a JSON file"""
# Unique identifier for the addon
bl_idname = 'import_export.armature2json'
# Display name in the interface
bl_label = 'Export Armature to JSON'
bl_options = {'REGISTER'}
bl_category = 'Import-Export'
def execute(self, context):
def main():
# Get the armature that is currently active. We will be parsing it's actions
# TODO: Error message if the active object is not the armature
activeArmature = bpy.context.view_layer.objects.active
# If the active object isn't an armature, we use the first armature that we find
if activeArmature.type != 'ARMATURE':
for obj in bpy.context.scene.objects:
if obj.type == 'ARMATURE':
activeArmature = obj
bpy.context.view_layer.objects.active = activeArmature
break
armatureJSON = {
'name': activeArmature.name,
'bone_space_actions': {},
'inverse_bind_poses': [],
'joint_indices': {},
'bone_child_to_parent': {},
'bone_groups': {}
}
# Get all of the actions
# TODO: If we later support handling multiple armatures we'll need to only use the
# actions that apply to the current armature
actionsList = list(bpy.data.actions)
bpy.ops.object.mode_set(mode = 'POSE')
# Select all of the armature's bones so that we can iterate over them later
# We get all bone names so that we are certain to always iterate over bones in a consistent
# order. We've had issues in the past where the order would be different depending on how you
# accessed the bones, so this should help prevent future errors.
allBoneNames = []
allPoseBones = {}
for poseBone in activeArmature.pose.bones:
poseBone.bone.select = True
allBoneNames.append(poseBone.name)
allPoseBones[poseBone.name] = poseBone
# Now we create the JSON for the joint name indices. The bind poses and keyframe poses are
# arrays of index 0...numBones - 1. To look up a bone in this array you use its joint name index
for boneIndex, boneName in enumerate(allBoneNames):
armatureJSON['joint_indices'][boneName] = boneIndex
# Parent indices
for boneName in allBoneNames:
poseBone = activeArmature.pose.bones[boneName]
bone_idx = armatureJSON['joint_indices'][boneName]
if poseBone.parent is not None:
parentIdx = armatureJSON['joint_indices'][poseBone.parent.name]
armatureJSON['bone_child_to_parent'][bone_idx] = parentIdx
# Start building our JSON
# The format is
# {
# someAction: { timeInSeconds: [bone1, bone2, bone3 ...], keyframe2: [bone1, bone2, bone3 ...] },
# anotherAction: { someTime: [bone1, bone2, bone3 ...], keyframe2: [bone1, bone2, bone3 ...], anotherTime: { ... } },
# }
#
# TODO: This is no longer the format. Re-write the docs after we port to Rust
for actionInfo in actionsList:
# Change to the action that we are currently parsing the data of
activeArmature.animation_data.action = bpy.data.actions.get(actionInfo.name)
action = activeArmature.animation_data.action
locationsRotationsScales = {}
# Get all of the keyframes for the current action. We'll iterate through them
# to get all of the bone data
actionKeyframes = getKeyframesInAction(activeArmature.animation_data.action)
# If this action has no keyframes we skip it
if actionKeyframes == []:
continue
armatureJSON['bone_space_actions'][actionInfo.name] = {
'bone_keyframes': {
'frame_range_inclusive': [math.floor(action.frame_range[0]), math.floor(action.frame_range[1])],
'keyframes': {}
},
'keyframes': [],
'pose_markers': {}
}
# TODO: Cross reference our implementation with this:
# https://github.com/HENDRIX-ZT2/bfb-blender/blob/master/export_bf.py#L81
for fcurve in action.fcurves:
# example: pose.bones["Lower.Body"].location
data_path = fcurve.data_path
channel = fcurve.array_index
prefix = 'pose.bones["'
if not data_path.startswith(prefix):
continue
path_pieces = data_path.replace(prefix, '').split('"].')
if len(path_pieces) < 2:
continue
# Lower.Body
boneName = path_pieces[0]
property = path_pieces[1]
if property not in ["location", "rotation_euler", "rotation_quaternion", "scale"]:
continue
if boneName not in allPoseBones:
continue
if boneName not in locationsRotationsScales:
locationsRotationsScales[boneName] = {}
for keyframe in fcurve.keyframe_points:
frame, val = keyframe.co
if frame not in locationsRotationsScales[boneName]:
locationsRotationsScales[boneName][frame] = {}
if property not in locationsRotationsScales[boneName][frame]:
locationsRotationsScales[boneName][frame][property] = {}
locationsRotationsScales[boneName][frame][property][channel] = val
for boneName, frames in locationsRotationsScales.items():
previous_rot_euler_0 = None
previous_rot_euler_1 = None
previous_rot_euler_2 = None
previous_rot_quat_w = 1
previous_rot_quat_x = 0
previous_rot_quat_y = 0
previous_rot_quat_z = 0
previous_trans_x = 0
previous_trans_y = 0
previous_trans_z = 0
previous_scale_x = None
previous_scale_y = None
previous_scale_z = None
for frame in sorted(frames):
transforms = frames[frame]
mat_loc = mathutils.Matrix.Translation((0, 0, 0))
mat_rot = mathutils.Euler((0, 0, 0), 'XYZ').to_matrix()
mat_scale = mathutils.Matrix.Scale(1.0, 4, (1.0, 1.0, 1.0))
poseBone = allPoseBones[boneName]
# Handles Blender baking optimization that deletes redundant keyframes when neighbors share the
# same value. We need to make sure to include the value in our transformation matrix
t = transforms.get('location') if transforms.get('location') is not None else {}
trans = [0, 0, 0]
trans[0] = t.get(0) if t.get(0) is not None else previous_trans_x
previous_trans_x = trans[0]
trans[1] = t.get(1) if t.get(1) is not None else previous_trans_y
previous_trans_y = trans[1]
trans[2] = t.get(2) if t.get(2) is not None else previous_trans_z
previous_trans_z = trans[2]
mat_loc = mathutils.Matrix.Translation(trans)
### ---
if poseBone.rotation_mode == 'QUATERNION':
q = transforms.get('rotation_quaternion') if transforms.get('rotation_quaternion') is not None else {}
quat = [0, 0, 0, 0]
quat[0] = q.get(0) if q.get(0) is not None else previous_rot_quat_w
previous_rot_quat_w = quat[0]
quat[1] = q.get(1) if q.get(1) is not None else previous_rot_quat_x
previous_rot_quat_x = quat[1]
quat[2] = q.get(2) if q.get(2) is not None else previous_rot_quat_y
previous_rot_quat_y = quat[2]
quat[3] = q.get(3) if q.get(3) is not None else previous_rot_quat_z
previous_rot_quat_z = quat[3]
mat_rot = mathutils.Quaternion(quat).to_matrix()
else:
euler = transforms.get('rotation_euler') if transforms.get('rotation_euler') is not None else {}
euler[0] = euler.get(0) if euler.get(0) is not None else previous_rot_euler_0
previous_rot_euler_0 = euler[0]
euler[1] = euler.get(1) if euler.get(1) is not None else previous_rot_euler_1
previous_rot_euler_1 = euler[1]
euler[2] = euler.get(2) if euler.get(2) is not None else previous_rot_euler_2
previous_rot_euler_2 = euler[2]
mat_rot = mathutils.Euler((euler[0], euler[1], euler[2]), poseBone.rotation_mode).to_matrix()
# FIXME: Treat this like the above. Need to re-write and test all of this when we port
# to Rust.
# if 'scale' in transforms:
# mat_scale = mathutils.Matrix.Scale(1.0, 4, transforms['scale'])
mat_rot = mat_rot.to_4x4()
local_space_transform_matrix = mat_loc @ mat_rot @ mat_scale
bone_idx = armatureJSON['joint_indices'][boneName]
if bone_idx not in armatureJSON['bone_space_actions'][actionInfo.name]['bone_keyframes']['keyframes']:
armatureJSON['bone_space_actions'][actionInfo.name]['bone_keyframes']['keyframes'][bone_idx] = []
# bpy.context.scene.frame_set(frame)
armatureJSON['bone_space_actions'][actionInfo.name]['bone_keyframes']['keyframes'][bone_idx].append({
'frame': math.floor(frame),
'bone': {'Matrix': matrixToArray(local_space_transform_matrix)}
})
for pose_marker in activeArmature.animation_data.action.pose_markers:
armatureJSON['bone_space_actions'][actionInfo.name]['pose_markers'][pose_marker.frame] = pose_marker.name
# Calculate bone inverse bind poses
for boneName in allBoneNames:
# Calculate the bone's inverse bind matrix
#
# taken from:
# https://blenderartists.org/forum/showthread.php?323968-Exporting-armature-amp-actions-how-do-you-get-the-bind-pose-and-relative-transform
# https://blender.stackexchange.com/a/15229/40607
poseBone = activeArmature.pose.bones[boneName]
# We make sure to account for the world offset of the armature since matrix_local is in armature space
# https://docs.blender.org/api/current/bpy.types.Bone.html#bpy.types.Bone.matrix_local
boneBindMatrix = activeArmature.matrix_world @ poseBone.bone.matrix_local
boneInverseBind = boneBindMatrix.copy().inverted()
armatureJSON['inverse_bind_poses'].append({'Matrix': matrixToArray(boneInverseBind)})
# Exporting bone groups
#
# 1. Deselect all bones in the armature
# 2. Iterate through each bone group and select the bones in the group
# 3. Add the selected bones to that bone group
bone_groups_names = activeArmature.pose.bone_groups.keys()
for poseBone in activeArmature.pose.bones:
poseBone.bone.select = False
for bone_group_index, bone_group_name in enumerate(bone_groups_names):
armatureJSON['bone_groups'][bone_group_name] = []
activeArmature.pose.bone_groups.active_index = bone_group_index
bpy.ops.pose.group_select()
for poseBone in bpy.context.selected_pose_bones:
bone_index = armatureJSON['joint_indices'][poseBone.bone.name]
armatureJSON['bone_groups'][bone_group_name].append(bone_index)
bpy.ops.pose.group_deselect()
# START_ARMATURE_JSON $BLENDER_FILEPATH $ARMATURE_NAME
# ... mesh json ...
# END_ARMATURE_JSON $BLENDER_FILEPATH $ARMATURE_NAME
#
# NOTE: Intentionally done in one print statement to get around
# a bug where other Blender output (in this case from bpy.ops.anim.keyframe_delete(override, type='LocRotScale')
# calls in blender-iks-to-fks) was getting mixed in with our JSON output
output = "START_ARMATURE_JSON " + bpy.data.filepath + " " + activeArmature.name
output += "\n"
output += json.dumps(armatureJSON)
output += "\n"
output += "END_ARMATURE_JSON " + bpy.data.filepath + " " + activeArmature.name
print(output)
return {'FINISHED'}
def getKeyframesInAction(action):
# TODO: Right now we aren't sorting these keyframes.
# We should sort them from lowest to highest (that's a more expected order).
keyframes = []
for fcurve in action.fcurves:
for keyframe in fcurve.keyframe_points:
x, y = keyframe.co
# Don't know why yet, but we encounter each keyframes a
# bunch of times. so need to make sure we only add them once
if x not in keyframes:
# convert from float to int and insert into our keyframe list
keyframes.append((math.ceil(x)))
return keyframes
def matrixToArray (matrix):
array = []
for row in range(0, 4):
for column in range(0, 4):
array.append(matrix[row][column])
return array
# Run our armature2json() add on
return main()
def register():
bpy.utils.register_class(ExportArmatureToJSON)
def unregister():
bpy.utils.unregister_class(ExportArmatureToJSON)
if __name__ == "__main__":
register()