apply_bond_forces()

void MayaFlux::Nodes::Network::PhysicsOperator::apply_bond_forces ( )

private

Pull each bonded particle toward its root with a spring.

Rest length scales with cbrt(root's accreted mass): a grown body's satellites settle at a wider spread than a fresh one's, the same way any fixed-density accumulation of matter occupies more volume as it gains mass. Growth is a wider swarm of small particles, not a bigger point.

Definition at line 547 of file PhysicsOperator.cpp.

{
    for (size_t i = 0; i < m_bond_root.size(); ++i) {
        uint32_t root = m_bond_root[i];
        if (root == i) {
            continue;
        }
 
        auto self_idx = resolve_global_index(i);
        auto root_idx = resolve_global_index(root);
        if (!self_idx || !root_idx) {
            continue;
        }
 
        auto& self_state = m_collections[self_idx->group].physics_state[self_idx->local];
        const auto& self_pos = m_collections[self_idx->group].collection->get_points()[self_idx->local].position;
        const auto& root_pos = m_collections[root_idx->group].collection->get_points()[root_idx->local].position;
 
        glm::vec3 delta = root_pos - self_pos;
        float distance = glm::length(delta);
        if (distance < 0.001F) {
            continue;
        }
 
        const float rest_length = m_bond_rest_length * std::cbrt(get_accreted_mass(root));
 
        glm::vec3 direction = delta / distance;
        self_state.force += direction * (m_bond_stiffness * (distance - rest_length));
    }
}

References get_accreted_mass(), m_bond_rest_length, m_bond_root, m_bond_stiffness, m_collections, and resolve_global_index().

Referenced by apply_forces().

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