ViewDesignEngine/include/vde/curves/tessellation.h

#pragma once
#include "vde/core/point.h"
#include <vector>
#include <array>
#include <functional>

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

/// Tessellate a parametric surface into a uniform triangle mesh
/// @param eval  Function(u,v) -> Point3D
/// @param res_u, res_v  Number of samples in u/v directions
/// @return Pairs of (vertices, triangle indices)
std::pair<std::vector<Point3D>, std::vector<std::array<int, 3>>>
tessellate(const std::function<Point3D(double,double)>& eval,
           int res_u, int res_v);

/// Adaptive tessellation based on normal-angle deviation
/// Recursively subdivides the parameter domain when the angular deviation
/// between corner normals exceeds the threshold.
/// @param eval        Function(u,v) -> Point3D
/// @param normal_fn   Function(u,v) -> Vector3D (unit normal)
/// @param min_res     Minimum subdivisions per direction (1 = single quad)
/// @param max_depth   Maximum recursion depth (limits total subdivisions)
/// @param angle_threshold_deg  Maximum normal-angle deviation in degrees
/// @return Pairs of (vertices, triangle indices)
std::pair<std::vector<Point3D>, std::vector<std::array<int, 3>>>
adaptive_tessellate(
    const std::function<Point3D(double,double)>& eval,
    const std::function<Vector3D(double,double)>& normal_fn,
    int min_res = 2, int max_depth = 6,
    double angle_threshold_deg = 5.0);

}  // namespace vde::curves