Fix DX12 imgui assert by using new API #588
Open
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
With PR google#581, samples on Windows hit the following assert: ``` Backend does not support ImGuiBackendFlags_RendererHasTextures, and font atlas is not built! Update backend OR make sure you called ImGui_ImplXXXX_NewFrame() function for renderer backend, which should call io.Fonts->GetTexDataAsRGBA32() / GetTexDataAsAlpha8(). ``` When PR google#581 updated imgui from 1.90.3 to 1.92.4, it pulled in an API change from 1.91.6: the DX12 backend should now be initialized with the ImGui_ImplDX12_InitInfo. The legacy function sets ImGuiBackendFlags_RendererHasTextures to false, whereas the new function sets it to true. The new API is largely the same as the old one, except it now wants: - A CommandQueue - Depth/Stencil format - SRV Descriptor Alloc/Free functions Based on example_win32_directx12, the last requirement seems complicated. However, we can continue to use the single SRV Descriptor by populating the LegacySingleSrv* fields. This lines up well with the legacy API parameters. Despite being "legacy" parameters, this still uses the new API and avoids the assert. I've created google#587 to shift away from the legacy API entirely since it's unknown how using the legacy API could break things in the future. Fixes google#586
footballhead
commented
Dec 13, 2025
| init_info.Device = grfx::dx12::ToApi(pApp->GetDevice())->GetDxDevice(); | ||
| // While the deprecated ImGui_ImplDX12_Init function created a command queue, I think (for | ||
| // simplicity) that we can just reuse the app's graphics queue. | ||
| init_info.CommandQueue = grfx::dx12::ToApi(pApp->GetGraphicsQueue())->GetDxQueue(); |
Collaborator
Author
There was a problem hiding this comment.
I'm not a DirectX expert (DirectXpert? ;) so would love some feedback on this approach
Member
There was a problem hiding this comment.
Not an expert either, main question would be: does this work?
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
With PR #581, samples on Windows hit the following assert:
When PR #581 updated imgui from 1.90.3 to 1.92.4, it pulled in an API change from 1.91.6: the DX12 backend should now be initialized with the
ImGui_ImplDX12_InitInfostruct. The legacy function setsImGuiBackendFlags_RendererHasTexturesto false, whereas the new function sets it to true.The new API is largely the same as the old one, except it now wants:
Based on
example_win32_directx12/main.cpp, the last requirement seems complicated. However, we can continue to use the single SRV Descriptor by populating theLegacySingleSrv*fields. This lines up well with the legacy API parameters. Despite being "legacy" parameters, this still uses the new API and avoids the assert. I've created #587 to shift away from the legacy API entirely since it's unknown how using the legacy API could break things in the future.Fixes #586