ViewDesignEngine/include/vde/curves/nurbs_surface.h

#pragma once
#include "vde/core/point.h"
#include "vde/curves/bspline_curve.h"
#include "vde/curves/nurbs_curve.h"
#include <vector>
#include <array>

namespace vde::curves {
using core::Point3D;
using core::Vector3D;

class NurbsSurface {
public:
    NurbsSurface(std::vector<std::vector<Point3D>> control_grid,
                 std::vector<double> knots_u, std::vector<double> knots_v,
                 std::vector<std::vector<double>> weights,
                 int degree_u, int degree_v);

    [[nodiscard]] Point3D evaluate(double u, double v) const;
    [[nodiscard]] Vector3D derivative_u(double u, double v) const;
    [[nodiscard]] Vector3D derivative_v(double u, double v) const;
    [[nodiscard]] Vector3D normal(double u, double v) const;

    [[nodiscard]] int degree_u() const { return degree_u_; }
    [[nodiscard]] int degree_v() const { return degree_v_; }
    [[nodiscard]] std::array<int, 2> num_control_points() const {
        return {static_cast<int>(cp_.size()), static_cast<int>(cp_.empty()?0:cp_[0].size())};
    }
    [[nodiscard]] const std::vector<double>& knots_u() const { return knots_u_; }
    [[nodiscard]] const std::vector<double>& knots_v() const { return knots_v_; }
    [[nodiscard]] const std::vector<std::vector<Point3D>>& control_points() const { return cp_; }
    [[nodiscard]] const std::vector<std::vector<double>>& weights() const { return weights_; }

    /// Create a ruled surface between two NURBS curves
    static NurbsSurface ruled(const NurbsCurve& c1, const NurbsCurve& c2);

    /// Create a surface of revolution
    static NurbsSurface revolve(const NurbsCurve& profile, const Point3D& axis_origin,
                                const Vector3D& axis_dir, double angle_rad);

    /// Tessellate to triangle mesh
    [[nodiscard]] std::pair<std::vector<Point3D>, std::vector<std::array<int,3>>>
    tessellate(int res_u, int res_v) const;

private:
    std::vector<std::vector<Point3D>> cp_;
    std::vector<double> knots_u_, knots_v_;
    std::vector<std::vector<double>> weights_;
    int degree_u_, degree_v_;
};

}  // namespace vde::curves