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omath/include/omath/projection/camera.hpp
2025-10-03 13:51:53 +03:00

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8.7 KiB
C++

//
// Created by Vlad on 27.08.2024.
//
#pragma once
#include "omath/linear_algebra/mat.hpp"
#include "omath/linear_algebra/vector3.hpp"
#include "omath/projection/error_codes.hpp"
#include <omath/trigonometry/angle.hpp>
#include <expected>
#include <type_traits>
#ifdef OMATH_BUILD_TESTS
// ReSharper disable once CppInconsistentNaming
class UnitTestProjection_Projection_Test;
#endif
namespace omath::projection
{
class ViewPort final
{
public:
float m_width;
float m_height;
[[nodiscard]] constexpr float aspect_ratio() const
{
return m_width / m_height;
}
};
using FieldOfView = Angle<float, 0.f, 180.f, AngleFlags::Clamped>;
template<class T, class MatType, class ViewAnglesType>
concept CameraEngineConcept =
requires(const Vector3<float>& cam_origin, const Vector3<float>& look_at, const ViewAnglesType& angles,
const FieldOfView& fov, const ViewPort& viewport, float znear, float zfar) {
// Presence + return types
{ T::calc_look_at_angle(cam_origin, look_at) } -> std::same_as<ViewAnglesType>;
{ T::calc_view_matrix(angles, cam_origin) } -> std::same_as<MatType>;
{ T::calc_projection_matrix(fov, viewport, znear, zfar) } -> std::same_as<MatType>;
// Enforce noexcept as in the trait declaration
requires noexcept(T::calc_look_at_angle(cam_origin, look_at));
requires noexcept(T::calc_view_matrix(angles, cam_origin));
requires noexcept(T::calc_projection_matrix(fov, viewport, znear, zfar));
};
template<class Mat4X4Type, class ViewAnglesType, class TraitClass>
requires CameraEngineConcept<TraitClass, Mat4X4Type, ViewAnglesType>
class Camera final
{
#ifdef OMATH_BUILD_TESTS
friend UnitTestProjection_Projection_Test;
#endif
public:
~Camera() = default;
Camera(const Vector3<float>& position, const ViewAnglesType& view_angles, const ViewPort& view_port,
const FieldOfView& fov, const float near, const float far) noexcept
: m_view_port(view_port), m_field_of_view(fov), m_far_plane_distance(far), m_near_plane_distance(near),
m_view_angles(view_angles), m_origin(position)
{
}
void look_at(const Vector3<float>& target)
{
m_view_angles = TraitClass::calc_look_at_angle(m_origin, target);
m_view_projection_matrix = std::nullopt;
}
protected:
[[nodiscard]] Mat4X4Type calc_view_projection_matrix() const noexcept
{
return TraitClass::calc_projection_matrix(m_field_of_view, m_view_port, m_near_plane_distance,
m_far_plane_distance)
* TraitClass::calc_view_matrix(m_view_angles, m_origin);
}
public:
[[nodiscard]] const Mat4X4Type& get_view_projection_matrix() const noexcept
{
if (!m_view_projection_matrix.has_value())
m_view_projection_matrix = calc_view_projection_matrix();
return m_view_projection_matrix.value();
}
void set_field_of_view(const FieldOfView& fov) noexcept
{
m_field_of_view = fov;
m_view_projection_matrix = std::nullopt;
}
void set_near_plane(const float near) noexcept
{
m_near_plane_distance = near;
m_view_projection_matrix = std::nullopt;
}
void set_far_plane(const float far) noexcept
{
m_far_plane_distance = far;
m_view_projection_matrix = std::nullopt;
}
void set_view_angles(const ViewAnglesType& view_angles) noexcept
{
m_view_angles = view_angles;
m_view_projection_matrix = std::nullopt;
}
void set_origin(const Vector3<float>& origin) noexcept
{
m_origin = origin;
m_view_projection_matrix = std::nullopt;
}
void set_view_port(const ViewPort& view_port) noexcept
{
m_view_port = view_port;
m_view_projection_matrix = std::nullopt;
}
[[nodiscard]] const FieldOfView& get_field_of_view() const noexcept
{
return m_field_of_view;
}
[[nodiscard]] const float& get_near_plane() const noexcept
{
return m_near_plane_distance;
}
[[nodiscard]] const float& get_far_plane() const noexcept
{
return m_far_plane_distance;
}
[[nodiscard]] const ViewAnglesType& get_view_angles() const noexcept
{
return m_view_angles;
}
[[nodiscard]] const Vector3<float>& get_origin() const noexcept
{
return m_origin;
}
[[nodiscard]] std::expected<Vector3<float>, Error>
world_to_screen(const Vector3<float>& world_position) const noexcept
{
auto normalized_cords = world_to_view_port(world_position);
if (!normalized_cords.has_value())
return std::unexpected{normalized_cords.error()};
return ndc_to_screen_position(*normalized_cords);
}
[[nodiscard]] std::expected<Vector3<float>, Error>
world_to_view_port(const Vector3<float>& world_position) const noexcept
{
auto projected = get_view_projection_matrix()
* mat_column_from_vector<float, Mat4X4Type::get_store_ordering()>(world_position);
if (projected.at(3, 0) == 0.0f)
return std::unexpected(Error::WORLD_POSITION_IS_OUT_OF_SCREEN_BOUNDS);
projected /= projected.at(3, 0);
if (is_ndc_out_of_bounds(projected))
return std::unexpected(Error::WORLD_POSITION_IS_OUT_OF_SCREEN_BOUNDS);
return Vector3<float>{projected.at(0, 0), projected.at(1, 0), projected.at(2, 0)};
}
[[nodiscard]]
std::expected<Vector3<float>, Error> view_port_to_screen(const Vector3<float>& ndc) const noexcept
{
const auto inv_view_proj = get_view_projection_matrix().inverted();
if (!inv_view_proj)
return std::unexpected(Error::INV_VIEW_PROJ_MAT_DET_EQ_ZERO);
auto inverted_projection =
inv_view_proj.value() * mat_column_from_vector<float, Mat4X4Type::get_store_ordering()>(ndc);
if (!inverted_projection.at(3, 0))
return std::unexpected(Error::WORLD_POSITION_IS_OUT_OF_SCREEN_BOUNDS);
inverted_projection /= inverted_projection.at(3, 0);
return Vector3<float>{inverted_projection.at(0, 0), inverted_projection.at(1, 0),
inverted_projection.at(2, 0)};
}
[[nodiscard]]
std::expected<Vector3<float>, Error> screen_to_world(const Vector3<float>& screen_pos) const noexcept
{
return view_port_to_screen(screen_to_ndc(screen_pos));
}
[[nodiscard]]
std::expected<Vector3<float>, Error> screen_to_world(const Vector2<float>& screen_pos) const noexcept
{
const auto& [x, y] = screen_pos;
return screen_to_world({x, y, 1.f});
}
protected:
ViewPort m_view_port{};
Angle<float, 0.f, 180.f, AngleFlags::Clamped> m_field_of_view;
mutable std::optional<Mat4X4Type> m_view_projection_matrix;
float m_far_plane_distance;
float m_near_plane_distance;
ViewAnglesType m_view_angles;
Vector3<float> m_origin;
private:
template<class Type>
[[nodiscard]] constexpr static bool is_ndc_out_of_bounds(const Type& ndc) noexcept
{
return std::ranges::any_of(ndc.raw_array(), [](const auto& val) { return val < -1 || val > 1; });
}
[[nodiscard]] Vector3<float> ndc_to_screen_position(const Vector3<float>& ndc) const noexcept
{
/*
^
| y
1 |
|
|
-1 ---------0--------- 1 --> x
|
|
-1 |
v
*/
return {(ndc.x + 1.f) / 2.f * m_view_port.m_width, (1.f - ndc.y) / 2.f * m_view_port.m_height, ndc.z};
}
[[nodiscard]] Vector3<float> screen_to_ndc(const Vector3<float>& screen_pos) const noexcept
{
return {screen_pos.x / m_view_port.m_width * 2.f - 1.f, 1.f - screen_pos.y / m_view_port.m_height * 2.f,
screen_pos.z};
}
};
} // namespace omath::projection