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Improves screen to world conversion accuracy #100

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Merged
merged 1 commit into from
Nov 8, 2025
Merged

Improves screen to world conversion accuracy #100

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28 changes: 21 additions & 7 deletions include/omath/projection/camera.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7,13 +7,17 @@
#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 <omath/trigonometry/angle.hpp>
#include <type_traits>

#ifdef OMATH_BUILD_TESTS
// ReSharper disable once CppInconsistentNaming
// ReSharper disable CppInconsistentNaming
class UnitTestProjection_Projection_Test;
class UnitTestProjection_ScreenToNdcTopLeft_Test;
class UnitTestProjection_ScreenToNdcBottomLeft_Test;
// ReSharper restore CppInconsistentNaming

#endif

namespace omath::projection
Expand Down Expand Up @@ -52,6 +56,8 @@ namespace omath::projection
{
#ifdef OMATH_BUILD_TESTS
friend UnitTestProjection_Projection_Test;
friend UnitTestProjection_ScreenToNdcTopLeft_Test;
friend UnitTestProjection_ScreenToNdcBottomLeft_Test;
#endif
public:
enum class ScreenStart
Expand Down Expand Up @@ -152,7 +158,6 @@ namespace omath::projection
return m_origin;
}


template<ScreenStart screen_start = ScreenStart::TOP_LEFT_CORNER>
[[nodiscard]] std::expected<Vector3<float>, Error>
world_to_screen(const Vector3<float>& world_position) const noexcept
Expand Down Expand Up @@ -206,17 +211,19 @@ namespace omath::projection
inverted_projection.at(2, 0)};
}

template<ScreenStart screen_start = ScreenStart::TOP_LEFT_CORNER>
[[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));
return view_port_to_screen(screen_to_ndc<screen_start>(screen_pos));
}

template<ScreenStart screen_start = ScreenStart::TOP_LEFT_CORNER>
[[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});
return screen_to_world<screen_start>({x, y, 1.f});
}

protected:
Expand Down Expand Up @@ -286,10 +293,17 @@ namespace omath::projection
return {(ndc.x + 1.f) / 2.f * m_view_port.m_width, (ndc.y / 2.f + 0.5f) * m_view_port.m_height, ndc.z};
}

template<ScreenStart screen_start = ScreenStart::TOP_LEFT_CORNER>
[[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};
if constexpr (screen_start == ScreenStart::TOP_LEFT_CORNER)
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};
else if (screen_start == ScreenStart::BOTTOM_LEFT_CORNER)
return {screen_pos.x / m_view_port.m_width * 2.f - 1.f,
(screen_pos.y / m_view_port.m_height - 0.5f) * 2.f, screen_pos.z};
else
std::unreachable();
}
};
} // namespace omath::projection
74 changes: 74 additions & 0 deletions tests/general/unit_test_projection.cpp
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Open in desktop
Original file line number Diff line number Diff line change
@@ -1,11 +1,13 @@
//
// Created by Vlad on 27.08.2024.
//
#include "omath/engines/unity_engine/camera.hpp"
#include <complex>
#include <gtest/gtest.h>
#include <omath/engines/source_engine/camera.hpp>
#include <omath/projection/camera.hpp>
#include <print>
#include <random>

TEST(UnitTestProjection, Projection)
{
Expand All @@ -22,4 +24,76 @@ TEST(UnitTestProjection, Projection)
EXPECT_NEAR(projected->x, 960.f, 0.001f);
EXPECT_NEAR(projected->y, 504.f, 0.001f);
EXPECT_NEAR(projected->z, 1.f, 0.001f);
}
TEST(UnitTestProjection, ScreenToNdcTopLeft)
{
constexpr auto fov = omath::Angle<float, 0.f, 180.f, omath::AngleFlags::Clamped>::from_degrees(90.f);
const auto cam = omath::source_engine::Camera({0, 0, 0}, omath::source_engine::ViewAngles{}, {1920.f, 1080.f}, fov,
0.01f, 1000.f);
using ScreenStart = omath::source_engine::Camera::ScreenStart;

const auto ndc_top_left = cam.screen_to_ndc<ScreenStart::TOP_LEFT_CORNER>({1500, 300, 1.f});
EXPECT_NEAR(ndc_top_left.x, 0.5625f, 0.0001f);
EXPECT_NEAR(ndc_top_left.y, 0.4444f, 0.0001f);
}

TEST(UnitTestProjection, ScreenToNdcBottomLeft)
{
constexpr auto fov = omath::projection::FieldOfView::from_degrees(60.f);

const auto cam = omath::unity_engine::Camera({0, 0, 0}, {}, {1280.f, 720.f}, fov, 0.03f, 1000.f);
using ScreenStart = omath::unity_engine::Camera::ScreenStart;

const auto ndc_bottom_left =
cam.screen_to_ndc<ScreenStart::BOTTOM_LEFT_CORNER>({1263.53833f, 547.061523f, 0.99405992f});
EXPECT_NEAR(ndc_bottom_left.x, 0.974278628f, 0.0001f);
EXPECT_NEAR(ndc_bottom_left.y, 0.519615293f, 0.0001f);
}

TEST(UnitTestProjection, ScreenToWorldTopLeftCorner)
{
std::mt19937 gen(std::random_device{}()); // Seed with a non-deterministic source

std::uniform_real_distribution dist_x(1.f, 1900.f);
std::uniform_real_distribution dist_y(1.f, 1070.f);

constexpr auto fov = omath::Angle<float, 0.f, 180.f, omath::AngleFlags::Clamped>::from_degrees(90.f);
const auto cam = omath::source_engine::Camera({0, 0, 0}, omath::source_engine::ViewAngles{}, {1920.f, 1080.f}, fov,
0.01f, 1000.f);
using ScreenStart = omath::source_engine::Camera::ScreenStart;

for (int i = 0; i < 100; i++)
{
const auto initial_screen_cords = omath::Vector2{dist_x(gen), dist_y(gen)};

const auto world_cords = cam.screen_to_world<ScreenStart::TOP_LEFT_CORNER>(initial_screen_cords);
const auto screen_cords = cam.world_to_screen<ScreenStart::TOP_LEFT_CORNER>(world_cords.value());

EXPECT_NEAR(screen_cords->x, initial_screen_cords.x, 0.001f);
EXPECT_NEAR(screen_cords->y, initial_screen_cords.y, 0.001f);
}
}

TEST(UnitTestProjection, ScreenToWorldBottomLeftCorner)
{
std::mt19937 gen(std::random_device{}()); // Seed with a non-deterministic source

std::uniform_real_distribution dist_x(1.f, 1900.f);
std::uniform_real_distribution dist_y(1.f, 1070.f);

constexpr auto fov = omath::Angle<float, 0.f, 180.f, omath::AngleFlags::Clamped>::from_degrees(90.f);
const auto cam = omath::source_engine::Camera({0, 0, 0}, omath::source_engine::ViewAngles{}, {1920.f, 1080.f}, fov,
0.01f, 1000.f);
using ScreenStart = omath::source_engine::Camera::ScreenStart;

for (int i = 0; i < 100; i++)
{
const auto initial_screen_cords = omath::Vector2{dist_x(gen), dist_y(gen)};

const auto world_cords = cam.screen_to_world<ScreenStart::BOTTOM_LEFT_CORNER>(initial_screen_cords);
const auto screen_cords = cam.world_to_screen<ScreenStart::BOTTOM_LEFT_CORNER>(world_cords.value());

EXPECT_NEAR(screen_cords->x, initial_screen_cords.x, 0.001f);
EXPECT_NEAR(screen_cords->y, initial_screen_cords.y, 0.001f);
}
}
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