Add access to deltaTime/getDt in SGCT/WindowWrapper

include/openspace/engine/wrapper/sgctwindowwrapper.h

@@ -42,6 +42,7 @@ public:
     bool windowHasResized() const override;
 
     double averageDeltaTime() const override;
+	double deltaTime() const override;
     glm::vec2 mousePosition() const override;
     uint32_t mouseButtons(int maxNumber) const override;
     glm::ivec2 currentWindowSize() const override;

include/openspace/engine/wrapper/windowwrapper.h

@@ -79,6 +79,12 @@ public:
      */
     virtual double averageDeltaTime() const;
 
+	/**
+	* Returns the frametime in seconds. On default, this method returns <code>0.0</code>.
+	* \return The frametime in seconds
+	*/
+	virtual double deltaTime() const;
+
     /**
      * Returns the location of the mouse cursor in pixel screen coordinates. On default,
      * this method returns <code>0,0</code>.

src/engine/wrapper/sgctwindowwrapper.cpp

@@ -61,6 +61,10 @@ bool SGCTWindowWrapper::windowHasResized() const {
 double SGCTWindowWrapper::averageDeltaTime() const {
     return sgct::Engine::instance()->getAvgDt();
 }
+
+double SGCTWindowWrapper::deltaTime() const {
+	return sgct::Engine::instance()->getDt();
+}
     
 glm::vec2 SGCTWindowWrapper::mousePosition() const {
     int id = sgct::Engine::instance()->getCurrentWindowPtr()->getId();

src/engine/wrapper/windowwrapper.cpp

@@ -45,6 +45,10 @@ bool WindowWrapper::windowHasResized() const {
 double WindowWrapper::averageDeltaTime() const {
     return 0.0;
 }
+
+double WindowWrapper::deltaTime() const {
+	return 0.0;
+}
     
 glm::vec2 WindowWrapper::mousePosition() const {
     return glm::vec2(0.f);