Bug: imDrawData->TotalVtxCount == 0 when reload application using imGUI.ini

[Rominitch]

Version of Dear ImGui:
1.62

Renderer/OS:
Vulkan/Windows 10 x64

My Issue:
I try to update https://github.com/SaschaWillems/Vulkan project with latest imGui v1.62 but strangely I find a crash with empty VtxCount after move dialog and relaunch exe.
I identify that if remove imGui.ini I can replay without issue.

So, I removed file configuration support temporarily (don't forget to comment it if you try).
See io.IniFilename = NULL;

I can't reproduce it on imgui_examples.sln. It's may be an implement issue inside SaschaWillems/Vulkan project ?

Workflow:
On my fork https://github.com/Rominitch/Vulkan,

• Compile and execute imgui project
• Resize dialog more larger and move imGUI window out of original dialog size.
• Close (check imgui.ini is correctly created)
• Reopen application
• Crash happens

Good Luck !
Regards

[ocornut]

but strangely I find a crash with empty VtxCount after move dialog and relaunch exe.

When you report a crash anywhere please try to provide a assert/line/callstack, thanks!

See #1893 i think it is the same problem (a missing zero test in some buffer updating code).
I guess @SaschaWillems code would need to be tweaked accordingly? And perhaps take a chance to update since 1.50 is rather old one.

[Rominitch]

Ok I will try soon to check where is issue into my fork code.

Sorry to forget information: currently crash doesn't happens inside ImGUI but Vulkan buffer's creation (because size of buffer is 0). So I don't have data to you.
I read very quickly you can dump a log of ImGUI, I 'm not very familliar with how to enable it.
I will attach it to ticket if I don't find solution myself ?

Thanks for your support !

[ocornut]

In your Vulkan renderer, Just don't create any buffer and commands if the ImDrawData is empty.

[Rominitch]

Hi !
All is OK now ! #1893 was my solution too.
I produce a new commit with fix on my fork.

Thanks !

[ocornut]

@Rominitch May I suggest pushing your changes as a Pull Request to the original SaschaWillems repository, so other people won't stumble on the same issue as much?

[Rominitch]

Yep ! Don't worry ! I created a ticket about that to inform community about this topic.

See SaschaWillems/Vulkan#496