+
+/* presentation */
+extern VkSurfaceKHR vksurface;
+extern VkSwapchainKHR vkswapchain;
+extern int vknum_swapchain_images;
+extern VkImage *vkswapchain_images;
+extern VkImageView *vkswapchain_views;
+extern int vk_curr_swapchain_image;
+extern VkSemaphore vk_img_avail_sema;
+extern VkSemaphore vk_rend_done_sema;