Struct Bone

pub struct Bone {
    pub transformation: Transformation,
    pub matrix_index: usize,
    /* private fields */
}

Each bone has a transformation with respect to its parent that is a translation (its origin relative to its parent origin), scale (in each direction, although a common scale for each coordinates is best), and an orientation of its contents provided by a quaternion (as a rotation).

A point in this bone’s space is then translate(rotate(scale(pt))) in its parent’s space. The bone’s children start with this transformation too.

From this the bone has a local bone-to-parent transform matrix and it has a local parent-to-bone transform matrix

At rest (where a mesh is skinned) there are two rest matrix variants Hence bone_relative = ptb * parent_relative

The skinned mesh has points that are parent relative, so animated_parent_relative(t) = btp(t) * ptb * parent_relative(skinned)

For a chain of bones Root -> A -> B -> C: bone_relative = C.ptb * B.ptb * A.ptb * mesh root = A.btp * B.btp * C.btp * C_bone_relative animated(t) = A.btp(t) * B.btp(t) * C.btp(t) * C.ptb * B.ptb * A.ptb * mesh

Fields

transformation: Transformation

rest transform - translation, scale, rotation

matrix_index: usize

Index into matrix array to put this bones animated mtm

Implementations

impl Bone

pub fn new(transformation: Transformation, matrix_index: usize) -> Self

Create a new bone with a given rest

pub fn borrow_transformation(&self) -> &Transformation

Borrow the transformation

pub fn set_transformation(self, transformation: Transformation) -> Self

Set the transformation of the bone

pub fn derive_matrices(&mut self, is_root: bool, parent_mtb: &Mat4) -> &Mat4

Derive matrices for the bone given a parent mesh-to-bone Mat4

pub fn borrow_mtb(&self) -> &Mat4

Borrow the mtb Matrix (for test mainly)

pub fn borrow_ptb(&self) -> &Mat4

Borrow the ptb Matrix (for test mainly)

Trait Implementations

impl Debug for Bone

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Bone

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl DefaultIndentedDisplay for Bone