added drag n drop function,

need to clean up before loading the next mesh

MshViewer/Source/callback.cpp

@@ -98,3 +98,10 @@ void keyPress(GLFWwindow *window, int key, int scancode, int action, int mods)
 		}
 	}
 }
+
+void dragNdrop(GLFWwindow* window, int count, const char** paths)
+{
+	OpenGLController* controller = reinterpret_cast<OpenGLController*>(glfwGetWindowUserPointer(window));
+	if(count > 0)
+		controller->loadMsh(paths[0]);
+}