capsule.hpp

 
#ifndef UFO_GEOMETRY_CAPSULE_HPP
#define UFO_GEOMETRY_CAPSULE_HPP
 
// UFO
#include <ufo/geometry/aabb.hpp>
#include <ufo/numeric/vec.hpp>
 
// STL
#include <concepts>
#include <cstddef>
#include <format>
#include <numbers>
#include <ostream>
 
namespace ufo
{
template <std::size_t Dim = 3, std::floating_point T = float>
struct Capsule {
    using value_type = T;
 
    Vec<Dim, T> start;
 
    Vec<Dim, T> end;
 
    T radius{};
 
    constexpr Capsule() noexcept = default;
 
    constexpr Capsule(Vec<Dim, T> const& start, Vec<Dim, T> const& end, T radius) noexcept
        : start(start), end(end), radius(radius)
    {
    }
 
    constexpr Capsule(Capsule const&) noexcept = default;
 
    template <std::convertible_to<T> U>
    constexpr explicit Capsule(Capsule<Dim, U> const& other) noexcept
        : start(Vec<Dim, T>(other.start))
        , end(Vec<Dim, T>(other.end))
        , radius(static_cast<T>(other.radius))
    {
    }
 
    [[nodiscard]] static constexpr std::size_t dimension() noexcept { return Dim; }
 
    [[nodiscard]] constexpr Vec<Dim, T> center() const noexcept
    {
        return (start + end) * T(0.5);
    }
 
    [[nodiscard]] constexpr T length() const noexcept { return ufo::length(end - start); }
 
    [[nodiscard]] constexpr AABB<Dim, T> aabb() const noexcept
    {
        return AABB<Dim, T>(ufo::min(start, end) - radius, ufo::max(start, end) + radius);
    }
 
    [[nodiscard]] constexpr bool isDegenerate() const noexcept { return radius < T(0); }
 
    [[nodiscard]] constexpr T diameter() const noexcept { return radius * T(2); }
 
    [[nodiscard]] constexpr T volume() const noexcept
    {
        T h = length();
        if constexpr (1 == Dim) {
            return h + diameter();
        } else if constexpr (2 == Dim) {
            return diameter() * h + std::numbers::pi_v<T> * radius * radius;
        } else if constexpr (3 == Dim) {
            T r2 = radius * radius;
            return std::numbers::pi_v<T> * r2 * h +
                   (T(4) / T(3)) * std::numbers::pi_v<T> * r2 * radius;
        } else {
            // TODO: Add 4D if requested
            return T(0);
        }
    }
 
    [[nodiscard]] bool operator==(Capsule const&) const = default;
};
 
//
// Deduction guides
//
 
template <std::size_t Dim, std::floating_point T>
Capsule(Vec<Dim, T>, Vec<Dim, T>, T) -> Capsule<Dim, T>;
 
template <std::size_t Dim, std::floating_point T>
std::ostream& operator<<(std::ostream& out, Capsule<Dim, T> const& capsule)
{
    return out << "Start: [" << capsule.start << "], End: [" << capsule.end
               << "], Radius: " << capsule.radius;
}
 
template <std::floating_point T>
using Capsule1 = Capsule<1, T>;
template <std::floating_point T>
using Capsule2 = Capsule<2, T>;
template <std::floating_point T>
using Capsule3 = Capsule<3, T>;
template <std::floating_point T>
using Capsule4 = Capsule<4, T>;
 
using Capsule1f = Capsule<1, float>;
using Capsule2f = Capsule<2, float>;
using Capsule3f = Capsule<3, float>;
using Capsule4f = Capsule<4, float>;
 
using Capsule1d = Capsule<1, double>;
using Capsule2d = Capsule<2, double>;
using Capsule3d = Capsule<3, double>;
using Capsule4d = Capsule<4, double>;
 
}  // namespace ufo
 
template <std::size_t Dim, std::floating_point T>
  requires std::formattable<T, char>
struct std::formatter<ufo::Capsule<Dim, T>> {
    constexpr auto parse(std::format_parse_context& ctx) { return ctx.begin(); }
 
    auto format(ufo::Capsule<Dim, T> const& capsule, std::format_context& ctx) const
    {
        return std::format_to(ctx.out(), "Start: [{}], End: [{}], Radius: {}", capsule.start,
                              capsule.end, capsule.radius);
    }
};
 
#endif  // UFO_GEOMETRY_CAPSULE_HPP