#include <hand.h>

Collaboration diagram for Hand:

[legend]

Classes
struct	PngImage

Public Member Functions
	Hand (Exoskeleton exo_handler, AnimatedHand anim_hand, const std::string &mesh_name, const std::string &graph_name, const std::string &texture_name, bool type, const Eigen::Vector3d &origin)
	Constructor. More...

void	update (const std::vector< AnimatedHand::EulerID > &euler_id)
	Updates the hand. More...

Eigen::MatrixXd	get_vertices (void)
	Returns the vertices of the hand. More...

Eigen::MatrixXi	get_surface_indices (void)

Private Attributes
Eigen::MatrixXd	m_vol_mesh_vert
	Volume mesh Vertices (V) More...

Eigen::MatrixXd	m_vol_mesh_vert_init

Eigen::MatrixXi	m_tetr_indices
	Volume mesh tetrahedral indices(T) and surface element indices(F) More...

Eigen::MatrixXi	m_surf_indices

Eigen::MatrixXi	m_bone_edges_indices
	Bone-edges skeleton indices (BE) More...

Eigen::VectorXi	m_point_handles
	Point handles list (P) More...

Eigen::MatrixXd	m_vertex_pos
	List of vertex positions (C) More...

Eigen::VectorXi	m_boundary_indices
	List of boundary indices (b) More...

Eigen::MatrixXd	m_boundary_conditions
	List of boundary conditions of each weight function (bc) More...

igl::BBWData	m_bbw_data
	BBW weights matrix (bbw_data) More...

Eigen::MatrixXd	m_weights
	List of weights (W) More...

Eigen::MatrixXd	m_g_weights
	Global weights (M) More...

Exoskeleton *	m_exo_handler
	Exoskeleton handler pointer. More...

AnimatedHand *	m_anim_hand
	Animated hand pointer. More...

std::vector< int >	m_hand_idx_iter
	Hand index iterator. More...

RotationList	m_anim_pose
	Animation pose. More...

int	m_pose_size = 20
	Pose size. More...

PngImage	m_texture
	Texture image. More...

bool	m_hand_type
	Hand type. More...

Eigen::Vector3d	m_origin
	Hand origin. More...

Detailed Description

Class Hand.

This class defines the hand and performs all the kinematics and the skinning of the hand. For this it uses the tecnique of Bounded Biharmonic Weights (BBW). See https://www.youtube.com/watch?v=P9fqm8vgdB8&ab_channel=AlecJacobson. libigl exposes a lot of functions for doing this. See https://github.com/libigl/libigl/blob/main/tutorial/403_BoundedBiharmonicWeights/main.cpp.

Definition at line 33 of file hand.h.

Constructor & Destructor Documentation

◆ Hand()

Hand::Hand	(	Exoskeleton *	exo_handler,
		AnimatedHand *	anim_hand,
		const std::string &	mesh_name,
		const std::string &	graph_name,
		const std::string &	texture_name,
		bool	type,
		const Eigen::Vector3d &	origin
	)

Constructor.

Construct a new Hand:: Hand object.

Parameters

exo_handler	Pointer to the Exoskeleton object.
anim_hand	Pointer to the AnimatedHand object.
mesh_name	The name of the mesh file.
graph_name	The name of the graph file (contains the conections between the bones aka the kinematic model).
texture_name	The name of the texture file.
type	Bool the define whether the hand is left(0) or right(1).
origin	The origin of the hand.

Definition at line 15 of file hand.cpp.

{
    // Read volume mesh
    igl::readMESH(mesh_name, m_vol_mesh_vert, m_tetr_indices, m_surf_indices);
 
    // Set initial mesh vertices
    m_vol_mesh_vert_init = m_vol_mesh_vert;
    
    // Read graph file
    igl::readTGF(graph_name, m_vertex_pos, m_bone_edges_indices);
 
    // Retrieve parents for forward kinematics
    igl::directed_edge_parents(m_bone_edges_indices, m_point_handles);
 
    // Set boundary conditions
    igl::boundary_conditions(m_vol_mesh_vert, m_tetr_indices, m_vertex_pos, 
        Eigen::VectorXi(), m_bone_edges_indices , Eigen::MatrixXi(),
        m_boundary_indices, m_boundary_conditions);
 
    // Only a few iterations
    m_bbw_data.active_set_params.max_iter = 8;
    m_bbw_data.verbosity = 2;
 
    if(!igl::bbw(m_vol_mesh_vert, m_tetr_indices, m_boundary_indices, 
        m_boundary_conditions, m_bbw_data, m_weights))
    {
        std::cout << "Error: BBW Error" << std::endl;
    }
 
    // Normalize weights to sum to one
    igl::normalize_row_sums(m_weights, m_weights);
 
    // Precompute linear blend skinning matrix
    igl::lbs_matrix(m_vol_mesh_vert, m_weights, m_g_weights);
 
    // Get exoskeleton handler pointer
    m_exo_handler = exo_handler;
 
    // Get animation hand pointer
    m_anim_hand = anim_hand;
 
    // Get hand index iterator
    m_hand_idx_iter = m_anim_hand->get_hand_idx_iterator();
 
    // Initialize animation pose
    m_anim_pose.resize(m_pose_size);
    
    for (size_t i = 0; i < m_pose_size; i++)
    {
        m_anim_pose.at(i) = Eigen::Quaterniond::Identity();
    }
 
    // Read texture
    igl::png::readPNG(texture_name, m_texture.red, m_texture.green,
        m_texture.blue, m_texture.a);
 
    // Get hand type
    m_hand_type = type;
 
    // Get hand origin
    m_origin = origin;
}

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Member Function Documentation

◆ get_surface_indices()

Eigen::MatrixXi Hand::get_surface_indices ( void )

inline

Returns: Eigen::MatrixXi Matrix of hand indices.

Definition at line 65 of file hand.h.

65{ return m_surf_indices; }

◆ get_vertices()

Eigen::MatrixXd Hand::get_vertices ( void )

inline

Returns the vertices of the hand.

Returns: Eigen::MatrixXd Matrix of hand vertices.

Definition at line 59 of file hand.h.

59{return m_vol_mesh_vert; }

◆ update()

void Hand::update ( const std::vector< AnimatedHand::EulerID > & euler_id )

Updates the hand.

It updates the hand vertices based on the euler angles for its skeleton joints. These are fed throught the AnimatedHand::EulerID struct. Based on the defined mapping it performs the forward kinematics and calcualtes all the hand vertices.

Parameters

euler_id The custom EulerID structure as described in AnimatedHand::EulerID.

Definition at line 87 of file hand.cpp.

{
    for (size_t i = 0; i < euler_id.size(); i++)
    {
        // Get euler id i
        std::vector<double> euler_i = euler_id.at(i).euler_angles;
 
        // // Get frame id i
        int frame_id_i = euler_id.at(i).frame_id;
 
        // Transform angles to quaternions
        EulerRotations::Quaternions quatern = 
            EulerRotations::euler_to_quaternions(euler_i.at(0),
            euler_i.at(1), euler_i.at(2));
 
        // Set animation pose
        m_anim_pose.at(frame_id_i) = Eigen::Quaterniond(quatern.w, quatern.x, 
            quatern.y, quatern.z);
    }
        
    // Propagate relative rotations via FK to retrieve absolute transformations
    RotationList v_rot;
    std::vector<Eigen::Vector3d> v_tran;
 
    // Forward kinematics 
    igl::forward_kinematics(m_vertex_pos, m_bone_edges_indices,
        m_point_handles, m_anim_pose, v_rot, v_tran);
 
    // Get verted dimension 
    int vert_dim = m_vertex_pos.cols();
 
    // Total transformation matrix
    Eigen::MatrixXd t_mat(m_bone_edges_indices.rows()*(vert_dim+1), vert_dim);
 
    // Perform trasnformation
    for (int i = 0 ; i < m_bone_edges_indices.rows(); i++)
    {
        Eigen::Affine3d a = Eigen::Affine3d::Identity();
 
        // Translate (has a trick to account for mirroring in case of right hand)
        a.translate(v_tran.at(i) + (-2.0 * (double)m_hand_type + 1) *  m_origin);
 
        // Rotate
        a.rotate(v_rot.at(i));
 
        t_mat.block(i*(vert_dim+1), 0, vert_dim+1, vert_dim) =
            a.matrix().transpose().block(0, 0, vert_dim+1, vert_dim);
    }
    
    // Compute deformation via LBS as matrix multiplication
    m_vol_mesh_vert = m_g_weights * t_mat;
        
    if (m_hand_type) // check if it's the right hand and mirror it
    {
        Eigen::Matrix3d mirror = Eigen::Matrix3d::Identity();
        mirror(0, 0) = -1.0;
        m_vol_mesh_vert = (mirror * m_vol_mesh_vert.transpose()).transpose();
    }
}

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Member Data Documentation

◆ m_anim_hand

AnimatedHand* Hand::m_anim_hand

private

Animated hand pointer.

Definition at line 105 of file hand.h.

◆ m_anim_pose

RotationList Hand::m_anim_pose

private

Animation pose.

Definition at line 111 of file hand.h.

◆ m_bbw_data

igl::BBWData Hand::m_bbw_data

private

BBW weights matrix (bbw_data)

Definition at line 91 of file hand.h.

◆ m_bone_edges_indices

Eigen::MatrixXi Hand::m_bone_edges_indices

private

Bone-edges skeleton indices (BE)

Definition at line 76 of file hand.h.

◆ m_boundary_conditions

Eigen::MatrixXd Hand::m_boundary_conditions

private

List of boundary conditions of each weight function (bc)

Definition at line 88 of file hand.h.

◆ m_boundary_indices

Eigen::VectorXi Hand::m_boundary_indices

private

List of boundary indices (b)

Definition at line 85 of file hand.h.

◆ m_exo_handler

Exoskeleton* Hand::m_exo_handler

private

Exoskeleton handler pointer.

Definition at line 102 of file hand.h.

◆ m_g_weights

Eigen::MatrixXd Hand::m_g_weights

private

Global weights (M)

Definition at line 97 of file hand.h.

◆ m_hand_idx_iter

std::vector<int> Hand::m_hand_idx_iter

private

Hand index iterator.

Definition at line 108 of file hand.h.

◆ m_hand_type

bool Hand::m_hand_type

private

Hand type.

Definition at line 120 of file hand.h.

◆ m_origin

Eigen::Vector3d Hand::m_origin

private

Hand origin.

Definition at line 123 of file hand.h.

◆ m_point_handles

Eigen::VectorXi Hand::m_point_handles

private

Point handles list (P)

Definition at line 79 of file hand.h.

◆ m_pose_size

int Hand::m_pose_size = 20

private

Pose size.

Definition at line 114 of file hand.h.

◆ m_surf_indices

Eigen::MatrixXi Hand::m_surf_indices

private

Definition at line 73 of file hand.h.

◆ m_tetr_indices

Eigen::MatrixXi Hand::m_tetr_indices

private

Volume mesh tetrahedral indices(T) and surface element indices(F)

Definition at line 73 of file hand.h.

◆ m_texture

PngImage Hand::m_texture

private

Texture image.

Definition at line 117 of file hand.h.

◆ m_vertex_pos

Eigen::MatrixXd Hand::m_vertex_pos

private

List of vertex positions (C)

Definition at line 82 of file hand.h.

◆ m_vol_mesh_vert

Eigen::MatrixXd Hand::m_vol_mesh_vert

private

Volume mesh Vertices (V)

Definition at line 70 of file hand.h.

◆ m_vol_mesh_vert_init

Eigen::MatrixXd Hand::m_vol_mesh_vert_init

private

Definition at line 70 of file hand.h.

◆ m_weights

Eigen::MatrixXd Hand::m_weights

private

List of weights (W)

Definition at line 94 of file hand.h.

The documentation for this class was generated from the following files:

include/hand.h
src/hand.cpp

Classes

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Hand()

Member Function Documentation

◆ get_surface_indices()

◆ get_vertices()

◆ update()

Member Data Documentation

◆ m_anim_hand

◆ m_anim_pose

◆ m_bbw_data

◆ m_bone_edges_indices

◆ m_boundary_conditions

◆ m_boundary_indices

◆ m_exo_handler

◆ m_g_weights

◆ m_hand_idx_iter

◆ m_hand_type

◆ m_origin

◆ m_point_handles

◆ m_pose_size

◆ m_surf_indices

◆ m_tetr_indices

◆ m_texture

◆ m_vertex_pos

◆ m_vol_mesh_vert

◆ m_vol_mesh_vert_init

◆ m_weights