ImplicitSurfaceNetwork/primitive_process/interface/subface/simple/plane.hpp

#pragma once

#include <base/subface.hpp>

namespace internal
{
// local: plane x=0
struct plane_t final : subface {
    static constexpr uint64_t             max_degree  = 1;
    static constexpr equation_system_type eq_sys_type = equation_system_type::implicit;

    std::function<double(Eigen::Vector3d)>          fetch_sdf_evaluator() const override;
    std::function<Eigen::Vector3d(Eigen::Vector3d)> fetch_sdf_grad_evaluator() const override;

    // u: planar local x-axis
    // v: planar local y-axis
    std::function<Eigen::Vector4d(double, double)> fetch_point_by_param_evaluator() const override;

    std::function<constraint_curve_intermediate(double)> fetch_curve_constraint_evaluator(parameter_u_t constraint_var_type,
                                                                                          double        u) const override;
    std::function<constraint_curve_intermediate(double)> fetch_curve_constraint_evaluator(parameter_v_t constraint_var_type,
                                                                                          double        v) const override;
    std::function<equation_intermediate_t(constraint_curve_intermediate &&)> fetch_solver_evaluator() const override;
};

struct plane_paired_model_matrix {
    internal::paired_model_matrix *data{};
};
} // namespace internal

namespace detail
{
template <>
struct hasher<internal::plane_paired_model_matrix> {
    size_t operator()(const internal::plane_paired_model_matrix &block) const
    {
        const auto& mat = block.data->local_to_world.matrix();

        Eigen::Vector3d n_vec = mat.col(0);
        double         tz    = mat.col(3).transpose().dot(n_vec);
        double norm = n_vec.norm();
        if (norm < 1e-8) {
            n_vec = Eigen::Vector3d::UnitZ();
            norm = 1.0;
        } else {
            n_vec /= norm;
        }
        double d = -tz / norm; // 平面方程: n·x = d

        // 可选：统一法向方向（例如让 z 分量优先为正）
        if (n_vec[2] < -1e-8 || 
            (std::abs(n_vec[2]) < 1e-8 && (n_vec[1] < -1e-8 || 
             (std::abs(n_vec[1]) < 1e-8 && n_vec[0] < 0)))) {
            n_vec = -n_vec;
            d = -d;
        }

        Eigen::Vector4d hash_key;
        hash_key << n_vec, d;
        
        return XXH3_64bits(hash_key.data(), sizeof(Eigen::Vector4d));
    }
};

template <>
struct default_elem_ctor<internal::plane_paired_model_matrix, internal::plane_t> {
    internal::plane_t operator()(const internal::plane_paired_model_matrix &k) const
    {
        internal::plane_t res{};
        res.model_matrices = const_cast<internal::paired_model_matrix *>(k.data);
        return res;
    }
};
} // namespace detail