From 0bd9eda48fa24f8e309860ad84117c7c389f77c2 Mon Sep 17 00:00:00 2001
From: Orange <orange-cpp@yandex.ru>
Date: Tue, 12 Aug 2025 09:12:57 +0300
Subject: [PATCH] Introduces CameraEngine concept

Adds a concept `CameraEngineConcept` to ensure that camera
engine implementations provide the necessary functions
with the correct signatures and `noexcept` specifications.

This enables compile-time checks for valid camera engine
implementations, improving code reliability and preventing
runtime errors.
---
 include/omath/projection/camera.hpp | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/include/omath/projection/camera.hpp b/include/omath/projection/camera.hpp
index 79eb191..76b07d8 100644
--- a/include/omath/projection/camera.hpp
+++ b/include/omath/projection/camera.hpp
@@ -26,7 +26,23 @@ namespace omath::projection
     };
     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
     {
     public: