Question: Is there (or should there be) support for a Direct3D7 backend?

[AndenDev]

Hi,

I’ve been experimenting with Dear ImGui on very old games, and I implemented a backend for Direct3D7.

• D3D7 is missing a few modern features:
  • No native scissor test → I implemented software triangle clipping against each command’s ClipRect.
  • Only 16-bit indices in DrawIndexedPrimitive → handled by enforcing ImDrawIdx = 16-bit and remapping.

So it’s working, and ImGui demos render correctly.
Here’s my question for the maintainers/community:

Does Dear ImGui plan to (or want to) officially support a Direct3D7 backend?

• I can open a PR with the backend implementation if there’s interest.
• Or if D3D7 is considered “too legacy / out of scope,” I’ll keep it as an external repo.

Thanks!

[ocornut]

Hello,
Nice work!

I cannot officially support a Direct3D7 backend, however if you have one I would encourage you to:

• (1) format it in a way that follow our standards (coding guidelines, function names, comments)
• (2) publish it e.g. somewhere on GitHub.

Then we can advertise it e.g in the list of backends at https://github.com/ocornut/imgui/wiki/Bindings and other places.

If you do (1) it will be easier to use and maintain IMHO.

[AndenDev]

Thanks! There’s still a bug in this project, but it works for now.

https://github.com/AndenDev/D3D7Imgui

[ocornut]

Thanks.
Added it to https://github.com/ocornut/imgui/wiki/Bindings.
Your repository is well done and documented.

If I may make a suggestion, you should remove imgui from the repository!

• Rename the repo to e.g. imgui_impl_dx7
• Remove all imgui files, move imgui_impl_dx7.cpp/.h to root directory.
• Let the example assume there is e.g. a ../imgui/ folder with imgui.
• Move all examples code to a folder.
• Remove imgui.ini.

So your folder structure would be:

repo: imgui_impl_dx7

• imgui_impl_dx7.cpp
• imgui_impl_dx7.h
• examples/
  • .sln, example_win32_directx7.cpp etc.

PS: I lost track of this because it hasn't been posted in issues (note how Discussions have large banners everywhere stating this shouldn't be posted in Discussions but in Issues 🙇 )

[ocornut]

You can also move all your vectors to ImGui_ImplDX7_Data so you keep them around instead of reallocating twice for every draw command. Also, using ImVector<> instead of std::vector<> will be faster particularly in debug builds.