ADD: Update Docs

src/core/game_api.cpp

@@ -640,7 +640,54 @@ void Engine::clear_all_instance_node_offsets(const std::string& instanceName)
 }
 
 // ----------------------------------------------------------------------------
-// Lighting
+// Lighting - Directional (Sunlight)
+// ----------------------------------------------------------------------------
+
+void Engine::set_sunlight_direction(const glm::vec3& dir)
+{
+    if (_engine->_sceneManager)
+    {
+        _engine->_sceneManager->setSunlightDirection(dir);
+    }
+}
+
+glm::vec3 Engine::get_sunlight_direction() const
+{
+    if (_engine->_sceneManager)
+    {
+        return _engine->_sceneManager->getSunlightDirection();
+    }
+    return glm::vec3(0.0f, -1.0f, 0.0f);
+}
+
+void Engine::set_sunlight_color(const glm::vec3& color, float intensity)
+{
+    if (_engine->_sceneManager)
+    {
+        _engine->_sceneManager->setSunlightColor(color, intensity);
+    }
+}
+
+glm::vec3 Engine::get_sunlight_color() const
+{
+    if (_engine->_sceneManager)
+    {
+        return _engine->_sceneManager->getSunlightColor();
+    }
+    return glm::vec3(1.0f);
+}
+
+float Engine::get_sunlight_intensity() const
+{
+    if (_engine->_sceneManager)
+    {
+        return _engine->_sceneManager->getSunlightIntensity();
+    }
+    return 1.0f;
+}
+
+// ----------------------------------------------------------------------------
+// Lighting - Point Lights
 // ----------------------------------------------------------------------------
 
 size_t Engine::add_point_light(const PointLight& light)
@@ -1139,6 +1186,19 @@ void Engine::hot_reload_shaders()
     }
 }
 
+// ----------------------------------------------------------------------------
+// Time
+// ----------------------------------------------------------------------------
+
+float Engine::get_delta_time() const
+{
+    if (_engine->_sceneManager)
+    {
+        return _engine->_sceneManager->getDeltaTime();
+    }
+    return 0.0f;
+}
+
 // ----------------------------------------------------------------------------
 // Statistics
 // ----------------------------------------------------------------------------

src/core/game_api.h

@@ -298,7 +298,20 @@ public:
     void clear_all_instance_node_offsets(const std::string& instanceName);
 
     // ------------------------------------------------------------------------
-    // Lighting
+    // Lighting - Directional (Sunlight)
+    // ------------------------------------------------------------------------
+
+    // Set sunlight direction (normalized automatically)
+    void set_sunlight_direction(const glm::vec3& dir);
+    glm::vec3 get_sunlight_direction() const;
+
+    // Set sunlight color and intensity
+    void set_sunlight_color(const glm::vec3& color, float intensity);
+    glm::vec3 get_sunlight_color() const;
+    float get_sunlight_intensity() const;
+
+    // ------------------------------------------------------------------------
+    // Lighting - Point Lights
     // ------------------------------------------------------------------------
 
     // Add point light (returns index)
@@ -399,6 +412,13 @@ public:
     // Hot reload all changed shaders
     void hot_reload_shaders();
 
+    // ------------------------------------------------------------------------
+    // Time
+    // ------------------------------------------------------------------------
+
+    // Get delta time in seconds for the current frame (clamped to 0.0-0.1)
+    float get_delta_time() const;
+
     // ------------------------------------------------------------------------
     // Statistics (read-only)
     // ------------------------------------------------------------------------

src/scene/vk_scene.cpp

@@ -147,10 +147,13 @@ void SceneManager::update_scene()
     _camera_position_local = world_to_local(mainCamera.position_world, _origin_world);
 
     // Simple per-frame dt (seconds) for animations
-    static auto lastFrameTime = std::chrono::steady_clock::now();
     auto now = std::chrono::steady_clock::now();
-    float dt = std::chrono::duration<float>(now - lastFrameTime).count();
-    lastFrameTime = now;
+    if (_lastFrameTime.time_since_epoch().count() == 0)
+    {
+        _lastFrameTime = now;
+    }
+    float dt = std::chrono::duration<float>(now - _lastFrameTime).count();
+    _lastFrameTime = now;
     if (dt < 0.f)
     {
         dt = 0.f;
@@ -159,6 +162,7 @@ void SceneManager::update_scene()
     {
         dt = 0.1f;
     }
+    _deltaTime = dt;
 
     auto tagOwner = [&](RenderObject::OwnerType type, const std::string &name,
                         size_t opaqueBegin, size_t transpBegin)
@@ -888,3 +892,29 @@ bool SceneManager::setGLTFInstanceAnimationLoop(const std::string &instanceName,
     it->second.animation.animationLoop = loop;
     return true;
 }
+
+void SceneManager::setSunlightDirection(const glm::vec3& dir)
+{
+    glm::vec3 normalized = glm::normalize(dir);
+    sceneData.sunlightDirection = glm::vec4(normalized, sceneData.sunlightDirection.w);
+}
+
+glm::vec3 SceneManager::getSunlightDirection() const
+{
+    return glm::vec3(sceneData.sunlightDirection);
+}
+
+void SceneManager::setSunlightColor(const glm::vec3& color, float intensity)
+{
+    sceneData.sunlightColor = glm::vec4(color, intensity);
+}
+
+glm::vec3 SceneManager::getSunlightColor() const
+{
+    return glm::vec3(sceneData.sunlightColor);
+}
+
+float SceneManager::getSunlightIntensity() const
+{
+    return sceneData.sunlightColor.w;
+}

src/scene/vk_scene.h

@@ -5,6 +5,7 @@
 #include <unordered_map>
 #include <memory>
 #include <optional>
+#include <chrono>
 #include <glm/vec2.hpp>
 #include <string>
 
@@ -85,6 +86,16 @@ public:
     void selectRect(const glm::vec2 &p0, const glm::vec2 &p1, std::vector<RenderObject> &outObjects) const;
 
     const GPUSceneData &getSceneData() const { return sceneData; }
+
+    // Sunlight (directional light) access
+    void setSunlightDirection(const glm::vec3& dir);
+    glm::vec3 getSunlightDirection() const;
+    void setSunlightColor(const glm::vec3& color, float intensity);
+    glm::vec3 getSunlightColor() const;
+    float getSunlightIntensity() const;
+
+    // Delta time (seconds) for the current frame
+    float getDeltaTime() const { return _deltaTime; }
     DrawContext &getMainDrawContext() { return mainDrawContext; }
 
     void loadScene(const std::string &name, std::shared_ptr<LoadedGLTF> scene);
@@ -203,6 +214,8 @@ private:
     glm::vec3 _camera_position_local{0.0f, 0.0f, 0.0f};
     double _floating_origin_recenter_threshold = 1000.0;
     double _floating_origin_snap_size = 100.0;
+    float _deltaTime = 0.0f;
+    std::chrono::steady_clock::time_point _lastFrameTime{};
 
     std::unordered_map<std::string, std::shared_ptr<LoadedGLTF> > loadedScenes;
     // Per-named static glTF scene animation state (independent of instances).