bullet3/Extras/InverseDynamics/DillCreator.cpp

#include "DillCreator.hpp"
#include <cmath>
namespace btInverseDynamics {

DillCreator::DillCreator(int level)
    : m_level(level),
      m_num_bodies(std::pow(2, level)),
      m_parent(m_num_bodies),
      m_parent_r_parent_body_ref(m_num_bodies),
      m_body_T_parent_ref(m_num_bodies),
      m_body_axis_of_motion(m_num_bodies),
      m_mass(m_num_bodies),
      m_body_r_body_com(m_num_bodies),
      m_body_I_body(m_num_bodies) {
    // generate names (for debugging)
    for (int i = 0; i < m_num_bodies; i++) {
        m_parent[i] = i - 1;

        // all z-axis (DH convention)
        m_body_axis_of_motion[i](0) = 0.0;
        m_body_axis_of_motion[i](1) = 0.0;
        m_body_axis_of_motion[i](2) = 1.0;
    }

    // recursively build data structures
    m_current_body = 0;
    const int parent = -1;
    const idScalar d_DH = 0.0;
    const idScalar a_DH = 0.0;
    const idScalar alpha_DH = 0.0;

    if (-1 == recurseDill(m_level, parent, d_DH, a_DH, alpha_DH)) {
        error_message("recurseDill failed\n");
        abort();
    }
}

DillCreator::~DillCreator() {}

int DillCreator::getNumBodies(int* num_bodies) const {
    *num_bodies = m_num_bodies;
    return 0;
}

int DillCreator::getBody(int body_index, int* parent_index, JointType* joint_type,
                         vec3* parent_r_parent_body_ref, mat33* body_T_parent_ref,
                         vec3* body_axis_of_motion, idScalar* mass, vec3* body_r_body_com,
                         mat33* body_I_body, int* user_int, void** user_ptr) const {
    if (body_index < 0 || body_index >= m_num_bodies) {
        error_message("invalid body index %d\n", body_index);
        return -1;
    }
    *parent_index = m_parent[body_index];
    *joint_type = REVOLUTE;
    *parent_r_parent_body_ref = m_parent_r_parent_body_ref[body_index];
    *body_T_parent_ref = m_body_T_parent_ref[body_index];
    *body_axis_of_motion = m_body_axis_of_motion[body_index];
    *mass = m_mass[body_index];
    *body_r_body_com = m_body_r_body_com[body_index];
    *body_I_body = m_body_I_body[body_index];

    *user_int = 0;
    *user_ptr = 0;
    return 0;
}

int DillCreator::recurseDill(const int level, const int parent, const idScalar d_DH_in,
                             const idScalar a_DH_in, const idScalar alpha_DH_in) {
    if (level < 0) {
        error_message("invalid level parameter (%d)\n", level);
        return -1;
    }

    if (m_current_body >= m_num_bodies || m_current_body < 0) {
        error_message("invalid body parameter (%d, num_bodies: %d)\n", m_current_body,
                      m_num_bodies);
        return -1;
    }

    idScalar size = std::max(level, 1);
    const int body = m_current_body;
    //  length = 0.1 * size;
    //  with = 2 * 0.01 * size;

    /// these parameters are from the paper ...
    /// TODO: add proper citation
    m_parent[body] = parent;
    m_mass[body] = 0.1 * std::pow(size, 3);
    m_body_r_body_com[body](0) = 0.05 * size;
    m_body_r_body_com[body](1) = 0;
    m_body_r_body_com[body](2) = 0;
    // initialization
    for (int i = 0; i < 3; i++) {
        m_parent_r_parent_body_ref[body](i) = 0;
        for (int j = 0; j < 3; j++) {
            m_body_I_body[body](i, j) = 0.0;
            m_body_T_parent_ref[body](i, j) = 0.0;
        }
    }
    const idScalar size_5 = pow(size, 5);
    m_body_I_body[body](0, 0) = size_5 / 0.2e6;
    m_body_I_body[body](1, 1) = size_5 * 403 / 1.2e6;
    m_body_I_body[body](2, 2) = m_body_I_body[body](1, 1);

    getVecMatFromDH(0, 0, a_DH_in, alpha_DH_in, &m_parent_r_parent_body_ref[body],
                    &m_body_T_parent_ref[body]);

    // attach "level" Dill systems of levels 1...level
    for (int i = 1; i <= level; i++) {
        idScalar d_DH = 0.01 * size;
        if (i == level) {
            d_DH = 0.0;
        }
        const idScalar a_DH = i * 0.1;
        const idScalar alpha_DH = i * M_PI / 3.0;
        m_current_body++;
        recurseDill(i - 1, body, d_DH, a_DH, alpha_DH);
    }

    return 0;  // ok!
}
}