I have a vulkan application that uses GLFW as its window manager.

Upon the window resize event, vulkan needs to update its drawable area. I have seen 2 ways that this is possible. One is to recreate the swapchain alongside all of the other objects that are tied to it and the other is to use dynamic state for the viewport so that recreation is not needed.

What is the difference between these two and when should I prefer one over the other?

CodePudding user response：

If the window is resized to a smaller size, the display engine may not force you to change your swapchain image sizes. It may inform you of this through the VK_SUBOPTIMAL_KHR error code (though it may not give you even that if performance of presenting is not affected). However, if the window is resized to be larger, the display engine may throw VK_ERROR_OUT_OF_DATE_KHR. That is not something you can ignore. Nor is it something a display engine can promise to never give you.

This means your code must be able to do swapchain rebuilding. Since you have to make allowances for this regardless, the only question is whether you do it whenever the window is resized or just when the display engine forces you to.

I would say that, if the display engine doesn't make you rebuild the swapchain, then it's probably faster not to. Using dynamic state isn't particularly slower than pipeline state, and its not like you're going to be changing it mid-frame. Indeed, you shouldn't rebuild all of your pipelines just because the swapchain was resized, so you should be using dynamic state for the viewport anyway.

In short: you ought to do both.