Add Dear ImGui internal, and cimgui_docking Zig module.

[floooh]

• make the imgui_internal.h API available in the code-generated src/cimgui.h and src-docking/cimgui.h
• make the docking branch available to Zig via a module cimgui_docking
• remove the outdated zimgui.h bindings (those were without C prefix but without prefix some C bindings function names collide with Win32 OS functions (like GetCursor).

[floooh]

Ok, @dom3d this is my alternative attempt.

There's 2 Zig modules cimgui and cimgui_docking, both contain the internal API.

This is how it works in the upstream project (by selectin between docking and non-docking via zig build or zig build -Ddocking.

floooh/sokol-zig-imgui-sample#3

E.g. the build.zig:

https://github.com/floooh/sokol-zig-imgui-sample/blob/imgui-docking/build.zig

...and the demo code:

https://github.com/floooh/sokol-zig-imgui-sample/blob/imgui-docking/src/main.zig

I don't access any internal API in this demo though.

The important part in the build zig is this:

https://github.com/floooh/sokol-zig-imgui-sample/blob/73f956662769b1c084e8d6cd9c2f8aa417ce9eb6/build.zig#L12-L15

E.g. for injecting the cimgui C header path into the sokol C library it's important to not confuse the src-docking and src path in the cimgui package, I forgot this at first and the result was that sokol_imgui.h was compiled with the non-docking version and the Zig code with the docking version - the result was that the demo appeared to work, but no docking was possible (which is actually surprising, I would have expected all sorts of weird crashes).

I may need to come up with a more fool-proof version later to select between the docking and non-docking version...

[floooh]

PS: ok I added a helper function getConfig() to the dcimgui/build.zig which makes it harder to mess up the Zig module and C header path:

https://github.com/floooh/sokol-zig-imgui-sample/blob/1658708bd2ed7bd80107f94bcace45933fcc5162/build.zig#L13-L17

I'll probably merge all that stuff on Sunday evening or Monday.

[floooh]

...I just went ahead and merged it already today ;)

[kassane]

cimgui_internal.h have <immintrin.h>, unsupported by importC.

• importC does not support __int128 or float16 used in x86 SIMD headers dlang/dmd#21543

[floooh]

@kassane is that a blocker for the D bindings? The internal API is still in a separate C header (cimgui_internal.h), so I guess the D bindings can just ignore that and only run cimgui.h through the importC step?

The other option might be to enable the C preprocessor define IMGUI_DISABLE_SSE for the importC step.

...but I'll also write a Dear ImGui ticket, it looks wrong that the imgui_internal.h header depends on intrinsics (instead of only the implementation).

[floooh]

Ah, it's used here in header as inline code:

https://github.com/ocornut/imgui/blob/336d9212fc25055a52107c70441c11acd12e8bb9/imgui_internal.h#L474-L476

...but still, using the IMGUI_DISABLE_SSE should fix that problem I think.

[kassane]

using the IMGUI_DISABLE_SSE should fix that problem I think.

Yeah! fixed in sokol-d/src/imgui/c/dcimgui.c.