From c90497f77b704374362196568776fe27c2949919 Mon Sep 17 00:00:00 2001
From: Orange <orange-cpp@yandex.ru>
Date: Mon, 25 Aug 2025 21:42:58 +0300
Subject: [PATCH] Fixes Unreal Engine view angle matrix order

The view angle rotation matrix order in Unreal Engine was incorrect, leading to incorrect camera orientation.

This commit fixes the order of rotation matrices to roll, pitch, yaw
to correctly implement Unreal Engine camera rotations.

Adds comprehensive unit tests for Unreal Engine formulas, camera and constants.

Marks Unreal Engine as supported in README.md.
---
 .idea/codeStyles/Project.xml              |   7 --
 .idea/codeStyles/codeStyleConfig.xml      |   1 +
 README.md                                 |   3 +-
 source/engines/unreal_engine/formulas.cpp |   6 +-
 tests/engines/unit_test_unreal_engine.cpp | 105 ++++++++++++++++++++++
 5 files changed, 111 insertions(+), 11 deletions(-)

diff --git a/.idea/codeStyles/Project.xml b/.idea/codeStyles/Project.xml
index defa978..5d6ba7c 100644
--- a/.idea/codeStyles/Project.xml
+++ b/.idea/codeStyles/Project.xml
@@ -182,19 +182,12 @@
       <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=2AD8EC23F81C6F4AB06852FBF796A3D1/@EntryIndexedValue" value="" type="string" />
       <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=2AD8EC23F81C6F4AB06852FBF796A3D1/@EntryIndexRemoved" value="true" type="bool" />
       <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=299C42B75F5A8C4DB381AE89010A7CC8/@EntryIndexedValue" value="&lt;NamingElement Priority=&quot;1&quot; Title=&quot;Namespaces&quot;&gt;&lt;Descriptor Static=&quot;Indeterminate&quot; Constexpr=&quot;Indeterminate&quot; Const=&quot;Indeterminate&quot; Volatile=&quot;Indeterminate&quot; Accessibility=&quot;NOT_APPLICABLE&quot;&gt;&lt;type Name=&quot;namespace&quot; /&gt;&lt;type Name=&quot;namespace alias&quot; /&gt;&lt;/Descriptor&gt;&lt;Policy Inspect=&quot;True&quot; WarnAboutPrefixesAndSuffixes=&quot;False&quot; Prefix=&quot;&quot; Suffix=&quot;&quot; Style=&quot;aa_bb&quot; /&gt;&lt;/NamingElement&gt;" type="string" />
-      <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=299C42B75F5A8C4DB381AE89010A7CC8/@EntryIndexRemoved" />
       <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=A279BB9D47B8754E9482D81B5D3B3489/@EntryIndexedValue" value="&lt;NamingElement Priority=&quot;2&quot; Title=&quot;Types&quot;&gt;&lt;Descriptor Static=&quot;Indeterminate&quot; Constexpr=&quot;Indeterminate&quot; Const=&quot;Indeterminate&quot; Volatile=&quot;Indeterminate&quot; Accessibility=&quot;NOT_APPLICABLE&quot;&gt;&lt;type Name=&quot;__interface&quot; /&gt;&lt;type Name=&quot;class&quot; /&gt;&lt;type Name=&quot;concept&quot; /&gt;&lt;type Name=&quot;enum&quot; /&gt;&lt;type Name=&quot;struct&quot; /&gt;&lt;type Name=&quot;type alias&quot; /&gt;&lt;type Name=&quot;type template parameter&quot; /&gt;&lt;type Name=&quot;typedef&quot; /&gt;&lt;type Name=&quot;union&quot; /&gt;&lt;/Descriptor&gt;&lt;Policy Inspect=&quot;True&quot; WarnAboutPrefixesAndSuffixes=&quot;False&quot; Prefix=&quot;&quot; Suffix=&quot;&quot; Style=&quot;AaBb&quot; /&gt;&lt;/NamingElement&gt;" type="string" />
-      <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=A279BB9D47B8754E9482D81B5D3B3489/@EntryIndexRemoved" />
       <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=82D01E1970D2F6419CE2737C415D3A01/@EntryIndexedValue" value="&lt;NamingElement Priority=&quot;3&quot; Title=&quot;Functions&quot;&gt;&lt;Descriptor Static=&quot;Indeterminate&quot; Constexpr=&quot;Indeterminate&quot; Const=&quot;Indeterminate&quot; Volatile=&quot;Indeterminate&quot; Accessibility=&quot;NOT_APPLICABLE&quot;&gt;&lt;type Name=&quot;global function&quot; /&gt;&lt;type Name=&quot;member function&quot; /&gt;&lt;/Descriptor&gt;&lt;Policy Inspect=&quot;True&quot; WarnAboutPrefixesAndSuffixes=&quot;False&quot; Prefix=&quot;&quot; Suffix=&quot;&quot; Style=&quot;aa_bb&quot; /&gt;&lt;/NamingElement&gt;" type="string" />
-      <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=82D01E1970D2F6419CE2737C415D3A01/@EntryIndexRemoved" />
       <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=2A0CD4590563D04B89402AC0279B5E10/@EntryIndexedValue" value="&lt;NamingElement Priority=&quot;4&quot; Title=&quot;Fields&quot;&gt;&lt;Descriptor Static=&quot;Indeterminate&quot; Constexpr=&quot;Indeterminate&quot; Const=&quot;Indeterminate&quot; Volatile=&quot;Indeterminate&quot; Accessibility=&quot;NOT_APPLICABLE&quot;&gt;&lt;type Name=&quot;class field&quot; /&gt;&lt;type Name=&quot;struct field&quot; /&gt;&lt;type Name=&quot;union member&quot; /&gt;&lt;/Descriptor&gt;&lt;Policy Inspect=&quot;True&quot; WarnAboutPrefixesAndSuffixes=&quot;False&quot; Prefix=&quot;&quot; Suffix=&quot;&quot; Style=&quot;aa_bb&quot; /&gt;&lt;/NamingElement&gt;" type="string" />
-      <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=2A0CD4590563D04B89402AC0279B5E10/@EntryIndexRemoved" />
       <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=DC1F6BB6E0EFFC49A38E940DB8A84CF6/@EntryIndexedValue" value="&lt;NamingElement Priority=&quot;5&quot; Title=&quot;Variables&quot;&gt;&lt;Descriptor Static=&quot;Indeterminate&quot; Constexpr=&quot;Indeterminate&quot; Const=&quot;Indeterminate&quot; Volatile=&quot;Indeterminate&quot; Accessibility=&quot;NOT_APPLICABLE&quot;&gt;&lt;type Name=&quot;global variable&quot; /&gt;&lt;type Name=&quot;lambda&quot; /&gt;&lt;type Name=&quot;local variable&quot; /&gt;&lt;/Descriptor&gt;&lt;Policy Inspect=&quot;True&quot; WarnAboutPrefixesAndSuffixes=&quot;False&quot; Prefix=&quot;&quot; Suffix=&quot;&quot; Style=&quot;aa_bb&quot; /&gt;&lt;/NamingElement&gt;" type="string" />
-      <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=DC1F6BB6E0EFFC49A38E940DB8A84CF6/@EntryIndexRemoved" />
       <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=AA17EF9DE2E5364DAEBE52F9EBBEA658/@EntryIndexedValue" value="&lt;NamingElement Priority=&quot;6&quot; Title=&quot;Parameters&quot;&gt;&lt;Descriptor Static=&quot;Indeterminate&quot; Constexpr=&quot;Indeterminate&quot; Const=&quot;Indeterminate&quot; Volatile=&quot;Indeterminate&quot; Accessibility=&quot;NOT_APPLICABLE&quot;&gt;&lt;type Name=&quot;function parameter&quot; /&gt;&lt;type Name=&quot;lambda parameter&quot; /&gt;&lt;/Descriptor&gt;&lt;Policy Inspect=&quot;True&quot; WarnAboutPrefixesAndSuffixes=&quot;False&quot; Prefix=&quot;&quot; Suffix=&quot;&quot; Style=&quot;aa_bb&quot; /&gt;&lt;/NamingElement&gt;" type="string" />
-      <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=AA17EF9DE2E5364DAEBE52F9EBBEA658/@EntryIndexRemoved" />
       <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=9BA140847B0718418342A07C8F0CE1ED/@EntryIndexedValue" value="&lt;NamingElement Priority=&quot;7&quot; Title=&quot;Macros&quot;&gt;&lt;Descriptor Static=&quot;Indeterminate&quot; Constexpr=&quot;Indeterminate&quot; Const=&quot;Indeterminate&quot; Volatile=&quot;Indeterminate&quot; Accessibility=&quot;NOT_APPLICABLE&quot;&gt;&lt;type Name=&quot;macro&quot; /&gt;&lt;/Descriptor&gt;&lt;Policy Inspect=&quot;True&quot; WarnAboutPrefixesAndSuffixes=&quot;False&quot; Prefix=&quot;&quot; Suffix=&quot;&quot; Style=&quot;AA_BB&quot; /&gt;&lt;/NamingElement&gt;" type="string" />
-      <option name="/Default/CodeStyle/Naming/CppNamingOptions/Rules/=9BA140847B0718418342A07C8F0CE1ED/@EntryIndexRemoved" />
     </RiderCodeStyleSettings>
     <clangFormatSettings>
       <option name="ENABLED" value="true" />
diff --git a/.idea/codeStyles/codeStyleConfig.xml b/.idea/codeStyles/codeStyleConfig.xml
index 79ee123..6e6eec1 100644
--- a/.idea/codeStyles/codeStyleConfig.xml
+++ b/.idea/codeStyles/codeStyleConfig.xml
@@ -1,5 +1,6 @@
 <component name="ProjectCodeStyleConfiguration">
   <state>
     <option name="USE_PER_PROJECT_SETTINGS" value="true" />
+    <option name="PREFERRED_PROJECT_CODE_STYLE" value="Default" />
   </state>
 </component>
\ No newline at end of file
diff --git a/README.md b/README.md
index e78e420..d47e66d 100644
--- a/README.md
+++ b/README.md
@@ -42,7 +42,8 @@ Oranges's Math Library (omath) is a comprehensive, open-source library aimed at
 | Source   | ✅YES    |
 | Unity    | ✅YES    |
 | IWEngine | ✅YES    |
-| Unreal   | ❌NO     |
+| OpenGL   | ✅YES    |
+| Unreal   | ✅YES    |
 
 ## Supported Operating Systems
 
diff --git a/source/engines/unreal_engine/formulas.cpp b/source/engines/unreal_engine/formulas.cpp
index 67788f0..90cb10d 100644
--- a/source/engines/unreal_engine/formulas.cpp
+++ b/source/engines/unreal_engine/formulas.cpp
@@ -30,9 +30,9 @@ namespace omath::unreal_engine
     }
     Mat4X4 rotation_matrix(const ViewAngles& angles) noexcept
     {
-        return mat_rotation_axis_x<float, MatStoreType::ROW_MAJOR>(angles.pitch)
-               * mat_rotation_axis_y<float, MatStoreType::ROW_MAJOR>(angles.yaw)
-               * mat_rotation_axis_z<float, MatStoreType::ROW_MAJOR>(angles.roll);
+        return mat_rotation_axis_x<float, MatStoreType::ROW_MAJOR>(angles.roll)
+               * mat_rotation_axis_y<float, MatStoreType::ROW_MAJOR>(angles.pitch)
+               * mat_rotation_axis_z<float, MatStoreType::ROW_MAJOR>(angles.yaw);
     }
     Mat4X4 calc_perspective_projection_matrix(const float field_of_view, const float aspect_ratio, const float near,
                                               const float far) noexcept
diff --git a/tests/engines/unit_test_unreal_engine.cpp b/tests/engines/unit_test_unreal_engine.cpp
index 12d601e..a57a936 100644
--- a/tests/engines/unit_test_unreal_engine.cpp
+++ b/tests/engines/unit_test_unreal_engine.cpp
@@ -1,3 +1,108 @@
 //
 // Created by Vlad on 8/25/2025.
 //
+//
+// Created by Orange on 11/27/2024.
+//
+#include <gtest/gtest.h>
+#include <omath/engines/unreal_engine/camera.hpp>
+#include <omath/engines/unreal_engine/constants.hpp>
+#include <omath/engines/unreal_engine/formulas.hpp>
+#include <print>
+
+TEST(unit_test_unreal_engine, ForwardVector)
+{
+    const auto forward = omath::unreal_engine::forward_vector({});
+
+    EXPECT_EQ(forward, omath::unreal_engine::k_abs_forward);
+}
+
+TEST(unit_test_unreal_engine, ForwardVectorRotationYaw)
+{
+    omath::unreal_engine::ViewAngles angles;
+
+    angles.yaw = omath::unreal_engine::YawAngle::from_degrees(90.f);
+
+    const auto forward = omath::unreal_engine::forward_vector(angles);
+    EXPECT_NEAR(forward.x, omath::unreal_engine::k_abs_right.x, 0.00001f);
+    EXPECT_NEAR(forward.y, omath::unreal_engine::k_abs_right.y, 0.00001f);
+    EXPECT_NEAR(forward.z, omath::unreal_engine::k_abs_right.z, 0.00001f);
+}
+
+TEST(unit_test_unreal_engine, ForwardVectorRotationPitch)
+{
+    omath::unreal_engine::ViewAngles angles;
+
+    angles.pitch = omath::unreal_engine::PitchAngle::from_degrees(-90.f);
+
+    const auto forward = omath::unreal_engine::forward_vector(angles);
+    EXPECT_NEAR(forward.x, omath::unreal_engine::k_abs_up.x, 0.00001f);
+    EXPECT_NEAR(forward.y, omath::unreal_engine::k_abs_up.y, 0.00001f);
+    EXPECT_NEAR(forward.z, omath::unreal_engine::k_abs_up.z, 0.00001f);
+}
+
+TEST(unit_test_unreal_engine, ForwardVectorRotationRoll)
+{
+    omath::unreal_engine::ViewAngles angles;
+
+    angles.roll = omath::unreal_engine::RollAngle::from_degrees(-90.f);
+
+    const auto forward = omath::unreal_engine::up_vector(angles);
+    EXPECT_NEAR(forward.x, omath::unreal_engine::k_abs_right.x, 0.00001f);
+    EXPECT_NEAR(forward.y, omath::unreal_engine::k_abs_right.y, 0.00001f);
+    EXPECT_NEAR(forward.z, omath::unreal_engine::k_abs_right.z, 0.00001f);
+}
+
+TEST(unit_test_unreal_engine, RightVector)
+{
+    const auto right = omath::unreal_engine::right_vector({});
+
+    EXPECT_EQ(right, omath::unreal_engine::k_abs_right);
+}
+
+TEST(unit_test_unreal_engine, UpVector)
+{
+    const auto up = omath::unreal_engine::up_vector({});
+    EXPECT_EQ(up, omath::unreal_engine::k_abs_up);
+}
+
+TEST(unit_test_unreal_engine, ProjectTargetMovedFromCamera)
+{
+    constexpr auto fov = omath::projection::FieldOfView::from_degrees(60.f);
+    const auto cam = omath::unreal_engine::Camera({0, 0, 0}, {}, {1280.f, 720.f}, fov, 0.01f, 1000.f);
+
+
+    for (float distance = 0.02f; distance < 100.f; distance += 0.01f)
+    {
+        const auto projected = cam.world_to_screen({distance, 0, 0});
+
+        EXPECT_TRUE(projected.has_value());
+
+        if (!projected.has_value())
+            continue;
+
+        EXPECT_NEAR(projected->x, 640, 0.00001f);
+        EXPECT_NEAR(projected->y, 360, 0.00001f);
+    }
+}
+
+TEST(unit_test_unreal_engine, CameraSetAndGetFov)
+{
+    constexpr auto fov = omath::projection::FieldOfView::from_degrees(90.f);
+    auto cam = omath::unreal_engine::Camera({0, 0, 0}, {}, {1920.f, 1080.f}, fov, 0.01f, 1000.f);
+
+    EXPECT_EQ(cam.get_field_of_view().as_degrees(), 90.f);
+    cam.set_field_of_view(omath::projection::FieldOfView::from_degrees(50.f));
+
+    EXPECT_EQ(cam.get_field_of_view().as_degrees(), 50.f);
+}
+
+TEST(unit_test_unreal_engine, CameraSetAndGetOrigin)
+{
+    auto cam = omath::unreal_engine::Camera({0, 0, 0}, {}, {1920.f, 1080.f}, {}, 0.01f, 1000.f);
+
+    EXPECT_EQ(cam.get_origin(), omath::Vector3<float>{});
+    cam.set_field_of_view(omath::projection::FieldOfView::from_degrees(50.f));
+
+    EXPECT_EQ(cam.get_field_of_view().as_degrees(), 50.f);
+}
\ No newline at end of file