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

namespace vde::mesh {

struct MCMesh {
    std::vector<Point3D> vertices;
    std::vector<std::array<int, 3>> triangles;
};

/// Marching Cubes for scalar field f(x,y,z)
/// Extracts isosurface at value = iso_level within the bounding box
MCMesh marching_cubes(const std::function<double(double,double,double)>& f,
                      double iso_level,
                      const Point3D& bmin, const Point3D& bmax,
                      int resolution);

/// SDF sphere
inline double sdf_sphere(double x, double y, double z, double cx, double cy, double cz, double r) {
    return std::sqrt((x-cx)*(x-cx) + (y-cy)*(y-cy) + (z-cz)*(z-cz)) - r;
}

/// SDF box
inline double sdf_box(double x, double y, double z, double hx, double hy, double hz) {
    double dx = std::abs(x) - hx, dy = std::abs(y) - hy, dz = std::abs(z) - hz;
    return std::sqrt(std::max(dx,0.0)*std::max(dx,0.0)
                   + std::max(dy,0.0)*std::max(dy,0.0)
                   + std::max(dz,0.0)*std::max(dz,0.0))
         + std::min(std::max({dx,dy,dz}), 0.0);
}

/// SDF smooth union
inline double sdf_smooth_union(double d1, double d2, double k) {
    double h = std::clamp(0.5 + 0.5*(d2-d1)/k, 0.0, 1.0);
    return std::lerp(d2, d1, h) - k*h*(1.0-h);
}

/// SDF smooth subtraction
inline double sdf_smooth_subtraction(double d1, double d2, double k) {
    double h = std::clamp(0.5 - 0.5*(d2+d1)/k, 0.0, 1.0);
    return std::lerp(d2, -d1, h) + k*h*(1.0-h);
}

}  // namespace vde::mesh