Vulkan present queue

[bluesky013]

Valid usage of vkGetDeviceQueue in vulkan spec declare "queueFamilyIndex must be one of the queue family indices specified when device was created, via the VkDeviceQueueCreateInfo structure" . Only graphic queue family index was specified when device was created. If present queue family index is not equal to graphic queue family index, would it be right?

[prideout]

I think you're right, to fix this I think we should add the second queue type into our deviceCreateInfo struct. Out of curiosity, is this causing a problem with a certain GPU?

[prideout]

This might be non-trivial to fix because the driver API allows clients to do certain things (e.g. upload a vertex buffer) before the swap chain is created. We need the swap chain in order to have a VkSurface, and we need a VkSurface in order to obtain a present queue family index.

Thankfully, this isn't causing issues on any devices that I know about.

[prideout]

@pixelflinger potential starter issue for someone in the Vulkan codebase

[poweifeng]

For record: we make the assumption that graphics queues can also present so the two QF index should be the same. If this assumption ever fails, we can revisit.