How can determine for normal and binormal axis in Joint orientation? RRS feed

  • Question

  • Hello Guys! I have some questions related on joint orientation.

    1. In SDK 2.0, it provides joint orientation as absoulte orientation of the parent bone. I understand that it means orientation of a bone is relative to the child joint and Spine_base. Is it right?

    2. In here, (

    this thread says ,

    The basis of each joint is defined by:

    - Bone direction(Y green) - always matches the skeleton.
    - Normal(Z blue) - joint roll, perpendicular to the bone
    - Binormal(X orange) - perpendicular to the bone and normal

    but it is little bit confusing about normal and binormal axis.

    the Bone direction(Y green) will be determined by vector of child joint-to-parent joint, but normal axis have to determine reference to certain plane(surface).

    what is the reference plane which can determine the normal axis?

    3. "absolute player orientation" have to determine before adrressing "absoulte orientation at local joint"

    In the case of SDK1.5-1.8, absolute player orientation can be determined by root joint. In the reference manual says, y-axis is upright,x-axis is left,zaxis faces the camera.

    but there's no implementation about how can we calculate the amount of rotation of the player(root joint rotation). The meaning of this question can be equal to "what is the reference joint" to determine rotation of the root joint?

    i'm little bit confusing of relative and absolute orientation in camera space and local space.

    Wednesday, October 28, 2015 6:46 AM