ImGui official port/integration

[mnesarco]

Hi Friends,

Maybe I am wrong but I see that the code required to use ImGui with bgfx is in examples/common/imgui, why not having an offcial port in a different repo like bgfx_imgui so it can be more official? That way the ImGui+bgfx docs, issues and contributions will be more visible and easy to find.

Thank you for all the hard work.

[bkaradzic]

bgfx_imgui so it can be more official

More official that being in main repo?!

It's not in separate repo because it doesn't work without bgfx itself, and because it depends on example harness (entry code) windowing support.

[mnesarco]

Having it in "examples" sounds not too "official" even if it is included in main repo. Maybe the whole examples/common can be in a folder named something like "integrations" at root or something like that.

By the way, this is only a suggestion. Thank you for creating this library.

[bkaradzic]

There is actually no promise that anything in example/common is working out of scope of bgfx examples.

[mnesarco]

Maybe it is a better idea to move the whole examples dir to its own repository, currently I don't know if some of the 3rdparty dependencies are for bgfx or for the examples. I see dear-imgui in 3rdparty but it is not a dependency of bgfx. So the dear-imgui dependency is at bgfx level but the actual integration code is at examples level. It is very confusing for newby people like me trying to use the library for the first time.

It would be great to have a pure bgfx repository with nothing more than what is required for bgfx usage. And other repositories with optional things like examples, imgui, nanovg, .. integrations...

I want to create an application with bgfx and Dear-ImGui (Docking branch), so if I understand correctly, I need to include bgfx (using cmake with your bgfx.cmake repo using add_subdirectory for simplicity), it includes the examples but I don't know if I can use imgui directly from the already included examples or do i need to copy that code into my own source tree. Also as i want to use a different branch of ImGui, do i need to replace the one included in bgfx 3rdparty or do i need to add my own copy (ending up with two different imgui sources)

Or maybe I am just very confused on how to use this.

[bkaradzic]

It would be great to have a pure bgfx repository with nothing more than what is required for bgfx usage. And other repositories with optional things like examples, imgui, nanovg, .. integrations...

Some other people complain that bx and bimg are not part of bgfx repo... You could integrate bgfx into your build system and not even bother with bgfx.cmake, and none of that example harness. You keep repeating integrations, but there are no integrations outside of scope of examples. For example, NanoVG there just demonstrates that bgfx can be used for vector graphics, and Dear ImGui is used to control examples.

Or maybe I am just very confused on how to use this.

It seems you have certain expectation of how repository should be organized, and bgfx repo is not matching your expectation. It's like trying to force square peg in a round hole. I think you should treat bgfx as 3rdparty library, ignore bgfx repo layout, and copy only things you need to your repo. See how 3rdparty directory looks in bgfx (all those repos have different layout than what's in bgfx repo).

[bkaradzic]

Since we're talking about Dear-ImGui here is example how layout looks in bgfx repo:
https://github.com/bkaradzic/bgfx/tree/master/3rdparty/dear-imgui

and this is how it looks verbatim:
https://github.com/bkaradzic/imgui

bgfx repo contains only files that are required to build for bgfx specific use case. Everything else is trimmed out.

[mnesarco]

Thank you for your answers. I am not trying to force any specific layout. I am just trying to understand the current layout. It is true that I am more familiar with cmake layouts but my goal is just to understand bgfx layout so I can use it in my own project in the correct way. So apparently the most sane approach is to build bgfx apart and install it to a know location, then use it as a binary dependency as i do with many other libraries.

Then I will copy some things from examples/common into my own source tree together with my own copy of imgui.

Sounds like a good approach?

[bkaradzic]

So apparently the most sane approach is to build bgfx apart and install it to a know location, then use it as a binary dependency as i do with many other libraries.

Yes, this is the best setup.

Then I will copy some things from examples/common into my own source tree together with my own copy of imgui.

Not sure about this part... I think it should work with your own copy of ImGui since my changes to ImGui are mostly related to my build setup.

[mnesarco]

Thank you very much.

[mnesarco]

Hi @bkaradzic ,

I have managed to setup a cmake project using your bgfx.cmake my main.cpp is just a copy of examples/00-helloworld/helloworld.cpp it works as expected with your version of imgui (3rdparty/dear-imgui) but if i replace the "vanilla" imgui files with the files from imgui docking branch it does render well but no mouse events are processed.

I am very new to bgfx and imgui, can you please give me an idea of what to search for? I will do the homework I just need some advice.

Thank you in advance.

[bdero]

@zhangfq-chemistry Take a look at the bgfx examples if you're trying to figure out how to draw with bgfx.

bgfx is an abstraction over N graphics APIs across M platform targets, not a high level renderer. So you may need to spend some time digging into the examples and referencing the docs in order to understand how to upload+bind resources, create+bind a raster pipeline, and submit draw calls -- especially if this is your first time writing a renderer or using graphics APIs in general.

[zhangfq-chemistry]

[ 81%] Built target bgfx
Consolidate compiler generated dependencies of target bgfx-imgui
[ 81%] Building CXX object 3rdparty/bgfx-imgui/CMakeFiles/bgfx-imgui.dir/src/bgfx/common/example-glue.cpp.o
/home/zhangfq/1/bgfx-with-imgui-example-cmake/3rdparty/bgfx-imgui/src/bgfx/common/example-glue.cpp: In function ‘void showExampleDialog(entry::AppI*, const char*)’:
/home/zhangfq/1/bgfx-with-imgui-example-cmake/3rdparty/bgfx-imgui/src/bgfx/common/example-glue.cpp:357:28: error: ‘ImGui::Font’ has not been declared
357 | ImGui::PushFont(ImGui::Font::Mono);

[mnesarco]

@zhangfq-chemistry have you updated the submodules before building?

git submodule update --init --recursive

[mnesarco]

@zhangfq-chemistry Finally I could reproduce your problem. I am looking for what is the cause.

[mnesarco]

Hi @zhangfq-chemistry

I have updated the repo. The problem was that I was using a GLOB pattern to select the files from dear-imgui and then copy some files from bgfx over that, but it turned out that cmake does not ovewrite existing files if the timestamp is not newer, so some files were not correctly overwritten. So I have removed the GLOB pattern and just list the desired files.

Please report if you could build now.

PS: Be sure to delete the old build directory first.

[mnesarco]

I have fixed a problem related to cmake cache optimization that prevents it to ovewrite some imgui files, and i have added an usage section in the readme.
https://github.com/mnesarco/bgfx-with-imgui-example-cmake