Getting the transform of a child bone

[angus]

I see that I can use getBoneTransform(index) to get the transformation matrix of a bone, but I cannot see how to get it for children bones of the bones that are returned when enumerating the ObjectMeshSkinned. Is there any way of getting those values?

[alexander]

Hi Angus,

index is a unique number for every bone in your ObjectMeshSkinned. Use getBoneTransform() to get transform of children or parent bones. It doesn't matter.
For example:

int bone_parent = mesh->findBone("my_parent_bone");
for (int i = 0; i < mesh->getNumBoneChildren(bone_parent); i++)
{
	int bone_child = mesh->getBoneChild(bone_parent, i);
	mat4 transform = mesh->getBoneTransform(bone_child);
}

Best regards,
Alexander

[angus]

5 hours ago, alexander said:

Hi Angus,

index is a unique number for every bone in your ObjectMeshSkinned. Use getBoneTransform() to get transform of children or parent bones. It doesn't matter.
For example:

 

I think there may be a bug in that case. The integers returned by 

mesh->getBoneChild(bone_parent, i);

are not unique. The values returned will be 1,2,3,4 for parent bones and bone 2 will have children bone IDs 1,2,3,4 as well.

 

ObjectMeshSkinnedPtr oms = ObjectMeshSkinned::cast(Editor::get()->getNodeById(1538661943));
    for (int i = 0; i < oms->getNumBones(); i++) {
        
        int childcount = oms->getNumBoneChildren(i);
        Log::message("Parent: [%d] [%d] [%s]\n", i, childcount, oms->getBoneName(i));
        if (childcount > 0) {
            for (int j = 0; j < oms->getNumBoneChildren(i); j++) {
                int child_id = oms->getBoneChild(i, j);
                Log::message("Child: [%d][%d][%s]\n", i, child_id, oms->getBoneName(child_id));
            }
        }
    }

 

 

 

[alexander]

Hi Angus,

I've imported standard MetaRig from Blender and all seems to work.
How your model looks like? Hierarchy? Can you give us small sample with your model?

Best regards,
Alexander

[angus]

That's odd. I've attached the FBX I'm using in testing and I get the output below:

Parent: [0] [0] [Head]
Parent: [1] [3] [Neck]
Child: [1][0][Head]
Child: [1][3][Clavicle_L]
Child: [1][4][Clavicle_R]
Parent: [2] [1] [Spine03]
Child: [2][1][Neck]
Parent: [3] [0] [Clavicle_L]
Parent: [4] [0] [Clavicle_R]

 

Which seems wrong to me as, for example, the child_id is 4 but a parent is also bone ID 4. Have I made a mistake in my enumeration code?

 

HumanMale_Bust.FBX

[alexander]

Hi,

child_id is 4 but a parent is also bone ID 4
As i said, "index is a unique number for every bone in your ObjectMeshSkinned".
ObjectMeshSkinned::getNumBones() returns all bones, including children. Not the roots only.
That's the reason why you are getting "Parent: [4] [0] [Clavicle_R]" and "Child: [1][4][Clavicle_R] ".
Change log messages to this and all will be clear to understand:

ObjectMeshSkinnedPtr oms = ObjectMeshSkinned::cast(Editor::get()->getNodeById(1538661943));
Log::message("List of all bones in ObjectMeshSkinned:\n");
for (int i = 0; i < oms->getNumBones(); i++) {
	int childcount = oms->getNumBoneChildren(i);
	Log::message("Bone \"%s\" (id: %d, children count: %d)\n", oms->getBoneName(i), i, childcount);
	if (childcount > 0) {
		for (int j = 0; j < oms->getNumBoneChildren(i); j++) {
			int child_id = oms->getBoneChild(i, j);
			Log::message("  Child \"%s\" (id: %d)\n", oms->getBoneName(child_id), child_id);
		}
	}
}

Best regards,
Alexander