Feature/camera upgrade

include/omath/engines/cry_engine/camera.hpp

@@ -9,5 +9,5 @@
 
 namespace omath::cry_engine
 {
-    using Camera = projection::Camera<Mat4X4, ViewAngles, CameraTrait, false, NDCDepthRange::ZERO_TO_ONE>;
+    using Camera = projection::Camera<Mat4X4, ViewAngles, CameraTrait, NDCDepthRange::ZERO_TO_ONE>;
 } // namespace omath::cry_engine

include/omath/engines/frostbite_engine/camera.hpp

@@ -9,5 +9,5 @@
 
 namespace omath::frostbite_engine
 {
-    using Camera =  projection::Camera<Mat4X4, ViewAngles, CameraTrait, false, NDCDepthRange::ZERO_TO_ONE>;
-} // namespace omath::unity_engine
+    using Camera =  projection::Camera<Mat4X4, ViewAngles, CameraTrait, NDCDepthRange::ZERO_TO_ONE>;
+} // namespace omath::frostbite_engine

include/omath/engines/iw_engine/camera.hpp

@@ -9,5 +9,5 @@
 
 namespace omath::iw_engine
 {
-    using Camera =  projection::Camera<Mat4X4, ViewAngles, CameraTrait, false, NDCDepthRange::ZERO_TO_ONE>;
+    using Camera =  projection::Camera<Mat4X4, ViewAngles, CameraTrait, NDCDepthRange::ZERO_TO_ONE>;
 } // namespace omath::iw_engine

include/omath/engines/opengl_engine/camera.hpp

@@ -8,5 +8,5 @@
 
 namespace omath::opengl_engine
 {
-    using Camera =  projection::Camera<Mat4X4, ViewAngles, CameraTrait, true, NDCDepthRange::NEGATIVE_ONE_TO_ONE>;
+    using Camera = projection::Camera<Mat4X4, ViewAngles, CameraTrait, NDCDepthRange::NEGATIVE_ONE_TO_ONE, {.inverted_forward = true}>;
 } // namespace omath::opengl_engine

include/omath/engines/source_engine/camera.hpp

@@ -7,5 +7,5 @@
 #include "traits/camera_trait.hpp"
 namespace omath::source_engine
 {
-    using Camera =  projection::Camera<Mat4X4, ViewAngles, CameraTrait, false, NDCDepthRange::ZERO_TO_ONE>;
+    using Camera =  projection::Camera<Mat4X4, ViewAngles, CameraTrait, NDCDepthRange::ZERO_TO_ONE>;
 } // namespace omath::source_engine

include/omath/engines/unity_engine/camera.hpp

@@ -9,5 +9,5 @@
 
 namespace omath::unity_engine
 {
-    using Camera = projection::Camera<Mat4X4, ViewAngles, CameraTrait, false, NDCDepthRange::ZERO_TO_ONE>;
+    using Camera = projection::Camera<Mat4X4, ViewAngles, CameraTrait, NDCDepthRange::ZERO_TO_ONE, {.inverted_forward = true}>;
 } // namespace omath::unity_engine

include/omath/engines/unreal_engine/camera.hpp

@@ -9,5 +9,5 @@
 
 namespace omath::unreal_engine
 {
-    using Camera = projection::Camera<Mat4X4, ViewAngles, CameraTrait, false, NDCDepthRange::ZERO_TO_ONE>;
+    using Camera = projection::Camera<Mat4X4, ViewAngles, CameraTrait, NDCDepthRange::ZERO_TO_ONE, {.inverted_right = true}>;
 } // namespace omath::unreal_engine

include/omath/projection/camera.hpp

@@ -42,6 +42,12 @@ namespace omath::projection
         AUTO,
         MANUAL,
     };
+    struct CameraAxes
+    {
+        bool inverted_forward = false;
+        bool inverted_right   = false;
+    };
+
     template<class T, class MatType, class ViewAnglesType>
     concept CameraEngineConcept =
             requires(const Vector3<float>& cam_origin, const Vector3<float>& look_at, const ViewAnglesType& angles,
@@ -58,8 +64,9 @@ namespace omath::projection
                 requires noexcept(T::calc_projection_matrix(fov, viewport, znear, zfar, ndc_depth_range));
             };
 
-    template<class Mat4X4Type, class ViewAnglesType, class TraitClass, bool inverted_z = false,
-             NDCDepthRange depth_range = NDCDepthRange::NEGATIVE_ONE_TO_ONE>
+    template<class Mat4X4Type, class ViewAnglesType, class TraitClass,
+             NDCDepthRange depth_range = NDCDepthRange::NEGATIVE_ONE_TO_ONE,
+             CameraAxes axes = {}>
     requires CameraEngineConcept<TraitClass, Mat4X4Type, ViewAnglesType>
     class Camera final
     {
@@ -83,6 +90,27 @@ namespace omath::projection
         {
         }
 
+        [[nodiscard]]
+        static ViewAnglesType calc_view_angles_from_view_matrix(const Mat4X4Type& view_matrix) noexcept
+        {
+            Vector3<float> forward_vector = {view_matrix[2, 0], view_matrix[2, 1], view_matrix[2, 2]};
+            if constexpr (axes.inverted_forward)
+                forward_vector = -forward_vector;
+            return TraitClass::calc_look_at_angle({}, forward_vector);
+        }
+
+        [[nodiscard]]
+        static Vector3<float> calc_origin_from_view_matrix(const Mat4X4Type& view_matrix) noexcept
+        {
+            // The view matrix is R * T(-origin), so the last column stores t = -R * origin.
+            // Recovering origin: origin = -R^T * t
+            return {
+                -(view_matrix[0, 0] * view_matrix[0, 3] + view_matrix[1, 0] * view_matrix[1, 3] + view_matrix[2, 0] * view_matrix[2, 3]),
+                -(view_matrix[0, 1] * view_matrix[0, 3] + view_matrix[1, 1] * view_matrix[1, 3] + view_matrix[2, 1] * view_matrix[2, 3]),
+                -(view_matrix[0, 2] * view_matrix[0, 3] + view_matrix[1, 2] * view_matrix[1, 3] + view_matrix[2, 2] * view_matrix[2, 3]),
+            };
+        }
+
         void look_at(const Vector3<float>& target)
         {
             m_view_angles = TraitClass::calc_look_at_angle(m_origin, target);
@@ -100,7 +128,7 @@ namespace omath::projection
         {
             const auto& view_matrix = get_view_matrix();
 
-            if constexpr (inverted_z)
+            if constexpr (axes.inverted_forward)
                 return -Vector3<float>{view_matrix[2, 0], view_matrix[2, 1], view_matrix[2, 2]};
             return {view_matrix[2, 0], view_matrix[2, 1], view_matrix[2, 2]};
         }
@@ -109,6 +137,8 @@ namespace omath::projection
         Vector3<float> get_right() const noexcept
         {
             const auto& view_matrix = get_view_matrix();
+            if constexpr (axes.inverted_right)
+                return -Vector3<float>{view_matrix[0, 0], view_matrix[0, 1], view_matrix[0, 2]};
             return {view_matrix[0, 0], view_matrix[0, 1], view_matrix[0, 2]};
         }