obj3d/bone provides all methods to deal with bones. The file contains 2 classes:

• cBone
• boneWeights

Class cBone

This class is used to work with a single bone.

Variables

These variables are all preset by __init__.

name	description
glob	reference to global object.
parentname	name of the parent bone or None.
name	name of the bone.
skeleton	reference to skeleton.
children	a list of children bones.
reference	a list of reference bones used for copying weights.
weightref	reference to weights, preset with None.
level	bone level (0 = root bone) + 1 for each child.
head	list of vertices for head.
tail	list of vertices for tail.
localplane	rotation plane for bone. (0 if not existing)
headPos	Numpy array of 3 elements for bone head position (default).
tailPos	Numpy array of 3 elements for bone tail position (default).
poseheadPos	Numpy array of 3 elements for bone head position (pose mode).
posetailPos	Numpy array of 3 elements for bone tail position (pose mode).
matRestGlobal	rest pose, global position 4x4 Matrix of bone object.
invRestGlobal	inverse global Matrix (to do less calculation).
matRestLocal	rest Pose, relative (local) position 4x4 Matrix of bone object.
matPoseGlobal	global pose matrix.
matPoseLocal	relative pose matrix, preset with 4x4 identity.
matPoseVerts	result of matRestLocal X matPoseLocal X inv(matRestGlobal).
length	length of bone

Methods:

name	parameters	returns	description
debugMats	None	None	A simple function to print matRestGlobal, matRestLocal.
getRestLocalRotQVector	None	quaternion vector	yields the rotation for bones.
getPoseLocalRotQVector	None	quaternion vector	yields the local rotation for bones in pose mode
getPoseGlobalRotQVector	None	quaternion vector	yields the global rotation for bones in pose mode. Used for gltf exporter.
getRestLocalTransVector	None	transition vector	return first 3 elements of last column of local rest matrix (transition vector)
getRestGlobalTransVector	None	transition vector	return first 3 elements of last column of global rest matrix (transition vector)
getPoseLocalTransVector	None	transition vector	return first 3 elements of last column of local pose matrix (transition vector)
getPoseGlobalTransVector	None	transition vector	return first 3 elements of last column of global pose matrix (transition vector). Used for gltf exporter.
getPoseRelParentRotQVector	None	quaternion vector	yields the global rotation for bones in pose mode relatively to parent bone. Used for gltf exporter.
getBindMatrix	orientation rotAxis offset	4x4 bindmat 4x4 bindinv	calculates the transformed rest matrix, then bindinv by transposing the rest matrix and calculating the inverse matrix from it. Last column is set to 0, 0, 0, 1 for gltf.
getTransformedRestMatrix	orientation rotAxis offset	4x4 restmatrix	calculates the rest matrix with changeOrientation() function.
getRelativeCorrection	None	None	calculates the relative correction by multiplying matRestGlobal, matPoseLocal, invRestGlobal
getNormal	None	None	Should calculate the normal, if a localplane is given as a string, the normals are calculated by skeleton getNormal. If no normal can be calculated or normals are close to zeros, normal is the y vector.
assignJointPos	head tail	None	sets headPos, tailPos
getJointPos	None	head, tail	Calculates head and tail position by mean values.
setJointPos	None	None	sets headPos, tailPos by calculation of mean position of head and tail.
calcLocalRestMat	normal	rest matrix	Calculates the local rest matrix by first calculating a normalize bone vector. For the orthonormal base, perpendicular vector to normal / bone_direction needed (cross-product). The missing axis x is calculated by using bone_direction and z_axis by cross product and calculating the norm. These values can now calculate the orthonormal base.
calcRestMatFromSkeleton	None	matrix calculation failed (bool)	First get the own normal and calculate local rest matrix from that normal. Assign this to matRestGlobal and calculate inverse global rest matrix. If that does not work, return with error (non singular matrix). To calculate local rest matrix, do a dot product of parent global rest matrix and own global restmatrix. For no parent bone the local and global matrices are equal.
restPose	None	None	set local pose matrix to identity.
calcLocalPoseMat	poseMat	None	Set local pose matrix to a 4x4 identity and copy posemat to matPoseLocal, then calculate the dot product of invRestGlobal .matPoseLocal, and the result again as a dot product of matRestGlobal, then add the translations from original bone (translations must be calculated with dot product and invRestGlobal.
calcGlobalPoseMat	None	None	matPoseGlobal is calculated by dot product of matRestLocal, matPoseLocal when no parent bone is available, otherwise parent bones matPoseGlobal must be used as second dot product. matPoseVerts are calculated by dot product of matPoseGlobal and invRestGlobal.
poseBone	None	None	poseheadPos and posetailPos are calculated by transposing headPos or tailPos and using this with a dot product of matPoseVerts and then transposing it back.

---

Class boneWeights

This class is used to support work with bone weights

Variables

These variables are all preset by __init__.

name	description
glob	reference to global object.
env	reference to environment object.
default_skeleton	reference to default skeleton.
root	reference to root of default skeleton.
bWeights	dictionary of weights, initialized empty.
mesh	reference to the mesh

Methods:

name	parameters	returns	description
createWeightsPerBone	wdict	None	Calculate the sums of normalize weights per bone, put these in verts and weights arrays The weights are sorted by index filter for values higher that 0.001. All what is not found is assigned to root bone. In this case a warning is given.
sortWeights	weights	weights	when using a custom skeleton, one bone may contain more than one bone of the default skeleton. sortWeights is needed, since deduplication is only working on sorted array.
deDuplicateWeights	weights	weights	weight arrays must be sorted before, for assets weights are calculated using 3 values from the base mesh, this means that values are used multiple times the skinning algorithm expects them once. This procedure is doing that by using np.unique to get occurences.
approxWeights	asset base	None	create bone weights from base, recalculate the input in case of mesh loaded in binary form for easier calculation (tested). form is: vertex_num: baseskeleton: [(vertexnum_asset, weight), (...) ]. In the end the weights must be deduplicated.
transferWeights	customskeleton	weights	if custom skeleton is not default skeleton, weights must be transfered. Then collect which bones of standard-skeleton are referenced by a bone. If bone is found in default, test "weights_reference". If available sum these up to one bone otherwise simply "copy" the weights. It is possible to define the same name for another bone but in this case reference must have 0 elements. The missing vertices must be distributed. This is done a by a parent chain reference, until a bone is found. (e.g. eyes will be transfered to head if no eye-bones) The values are sorted and deduplicated.
loadJSON	path	success (bool)	Loads JSON file and sets attributes, checks if "weights" are a value and creates weights per bone.