Strange clipping behavior in vulkan demo #821
Description
When compiling/running the glfw_vulkan demo on NixOS 25.05 with the glfw, vulkan-loader, and vulkan-headers packages installed, I get the following weird clipping behavior:
2025-06-28.22-56-45.mp4
For comparison, the glfw_opengl4 demo works perfectly for me.
I am sometimes getting a bunch of warnings like this from the validation layer:
Swapchain image 2 was presented but was not re-acquired, so VkSemaphore 0x310000000031 may still be in use and cannot be safely reused with image index 3.
Vulkan insight: One solution is to assign each image its own semaphore. Here are some common methods to ensure that a semaphore passed to vkQueuePresentKHR is not in use and can be safely reused:
a) Use a separate semaphore per swapchain image. Index these semaphores using the index of the acquired image.
b) Consider the VK_EXT_swapchain_maintenance1 extension. It allows using a VkFence with the presentation operation.
The Vulkan spec states: Each binary semaphore element of the pSignalSemaphores member of any element of pSubmits must be unsignaled when the semaphore signal operation it defines is executed on the device (https://docs.vulkan.org/spec/latest/chapters/cmdbuffers.html#VUID-vkQueueSubmit-pSignalSemaphores-00067)
validation layer: vkQueueSubmit(): pSubmits[0].pSignalSemaphores[0] (VkSemaphore 0x310000000031) is being signaled by VkQueue 0x1eb83170, but it may still be in use by VkSwapchainKHR 0x50000000005.
Here are the most recently acquired image indices: 0, 1, 2, [3], 4.
(brackets mark the last use of VkSemaphore 0x310000000031 in a presentation operation)
Sometimes these warnings does not show up. In either case, the demo is broken in the way shown in the mp4 attached above.
What could this be about?