ocornut
Weird flicker when using vulkan
I have been using bsf's Vulkan backend for quite a long time but I have run into a few problems with imgui. Whenever I move from one element to another things seem to flicker. Even when hovering over different parts of the ui different parts of the screen flicker and a picture that looks a bit like a font atlas shows up. Some widgets like DragFloat do not cause any problems. Navigating around the Demo window does not cause any problems. The examples also do not have this problem. Could this be a syncronization issue as from what I understand bsf does not wait on a fence. I think it only uses vkAcquireNextImage to wait on the image to become available and every frame just checks if any of the submitted command buffers are finished and resets them. But if that's the case then won't it flicker all the time? Also it seems more prevalent on higher framerates. In RenderDoc(at about 500fps) it rarely happens. If i wait after every command buffer submission the problem goes away.
Version: 1.85 Back-ends: imgui_impl_glfw.cpp + imgui_impl_vulkan.cpp OS: Ubuntu
Are the Vulkan validation layers enabled? If so, do they have any warnings?
What GPU are you using, AMD or Nvidia? I'm having a similar problem on windows with an AMD GPU.
I am perhaps seeing something similar.
For me it occurs when I click a Button element in a different Begin()/End() pair. The glitch can be seen on clicking the button, whereby I think the Mouse Press Down on Button changes the vertex/index vectors but doesnt trigger the command buffers to be recomputed for the new offsets.
I was using the vulkan demos from Sascha Willems and managed to remove the flicker by forcing this line to return true every frame, so that the buffers are reset each frame.
I have the same issue. For me it only occurs when I add lighting to the scene. I can't figure out why this is happening. When i change my frames in flight to 1 the problem goes away.
I think i figured out the problem. I'm not creating a vertex and index buffer per frame in flight.