add IMGUI support

[kassane]

fix #10

old branch, need long rebase... I'll delete (for testing only) https://github.com/kassane/sokol-d/tree/imgui-support

inspired by:

• https://github.com/floooh/sokol-zig/pull/69
• https://github.com/floooh/sokol-zig/pull/70

[kassane]

Need cimgui binding for run example. Old module amalgamation cimgui + sokol_imgui: https://github.com/kassane/sokol-d/blob/1d1fc586969aba82fc6b854aeb2d16f7ec656976/src/sokol/imgui.d

now, only sokol_imgui: https://github.com/kassane/sokol-d/blob/1110006dd280fca4be0a16402fc6455f1c82f494/src/examples/imgui.d#L103-L115

[kassane]

Some questions (for zig-dev)

What would you add cimgui to the example?

Unlike zig translate-c, importC doesn't read header, only C source. However, this still falls short (translate-c also has some issues). The only difference between the two projects is the level of support (zig project wins here).

More info - commands

Zig `translate-c` has the ability to convert all the code (declaration + implementation), `importC` just the declaration (equivalent to rust-bindgen or sokol_gen). ```bash # zig $ zig translate-c -cflags -- -lc # D $ ldmd2/ldc2 -Hf= (*.di) # zig have inside clang, # ldc2 need call cc (system compiler) - like rustc. # But -gcc=(custom CC) is used only C source and -linker=(custom LD) or -link-internally (inside lld, like zig) any object (w/o C source) # and rustc equivalence is -linker= flag. ```

And not have current D module about cimgui, only old imgui (C++, no extern(C)) version.

[kassane]

Please, @floooh.

Test it!

Preview

- Linux (native):  - Wasm32/Firefox: 

Note: For wasm32 build change... https://github.com/kassane/sokol-d/blob/8d589cb82b9a509f561147e3feec853cc1663157/build.zig#L245

Why block? CI error. Why imgui-cpp need assert.h, but rebuild (no-clean global cache) works!

And for old ldc2 versions (1.36...1.38 [latest]) change... .freestanding to .emscripten or try ldc2-master https://github.com/kassane/sokol-d/blob/8d589cb82b9a509f561147e3feec853cc1663157/build.zig#L512-L515

[floooh]

Note that there was an bug in the translateC step in the cimgui sample which caused this above error about missing assert.h in imgui.h when trying to build for wasm32-emscripten. I fixed this by always running the translateC step with the host target (instead of the build target):

https://github.com/floooh/sokol-zig-imgui-sample/blob/b2fd57bc0ddc406fc3a66160fa37ca27842ad127/deps/cimgui/build.zig#L51

...otherwise I would somehow need to inject the Emscripten include path into the translateC step. Using the host triplet is the better solution though, since there no platform-specific stuff happening in the translateC step.

[kassane]

Note that there was an bug in the translateC step in the cimgui sample which caused this above error about missing assert.h in imgui.h when trying to build for wasm32-emscripten. I fixed this by always running the translateC step with the host target [...]

According to this solution, perhaps it would have been possible to use importC to bypass the error, just like translate-c. However, the assert.h error occurs during the libsokol build, a step before ldc2. I know there exists a step wait for emsdk_setup in libsokol and this will run imgui in a direct dependency.

https://github.com/kassane/sokol-d/blob/20fe32c375502d2d4bc709086a0fdd2027e31f0c/build.zig#L79-L82 https://github.com/kassane/sokol-d/blob/20fe32c375502d2d4bc709086a0fdd2027e31f0c/build.zig#L184-L194

---

Another question that puzzles me. Would it be useful to use the build.zig dependency to make sokol-zig a dependency of sokol-d? That way we could reduce the complexity redundancy of build.zig.

[kassane]

@floooh , my assert.h fix - if with_imgui enabled, move lib.step.dependOn(&emsdk_setup.step); to libimgui.step.dependOn(&emsdk_setup.step); https://github.com/kassane/sokol-d/commit/bca71beb160425aeecf7a76f7256f4e2ca356744

[floooh]

Ah btw, I fixed this a bit differently, by letting the cimgui library depend on the sokol C library (up in the top level project):

https://github.com/floooh/sokol-zig-imgui-sample/blob/87d703e2f1f43135a5a5e9bfc2a56910d48b7e7b/build.zig#L69-L73

Since the sokol C library depends on the Emscripten SDK setup this also guarantees that the SDK is setup when cimgui is compiled (e.g. the idea is that all C libraries need to depend on the sokol C library... but maybe this could indeed be moved up into sokol-zig since we're iterating over the C libraries anyway in the linker step - also the injection of the Emscripten include path... hmm...)

Another question that puzzles me. Would it be useful to use the build.zig dependency to make sokol-zig a dependency of sokol-d?

Not a fan tbh, it would probably make more sense to move the emsdk stuff into a separate project (and Zig package) which could then be used both by sokol-zig and sokol-d.

[floooh]

Wrote a ticket for that idea (to handle the C library stuff in sokol-zig build.zig): https://github.com/floooh/sokol-zig/issues/71

[kassane]

it would probably make more sense to move the emsdk stuff into a separate project (and Zig package) which could then be used both by sokol-zig and sokol-d.

Make sense. Like, https://github.com/kassane/anotherBuildStep (a.k.a abs) Also, I have not yet completed emsdk support. But in pacman.d, besides sokol-d (passing libsokol + D modules), using abs to set ldc2. Maybe ldc2/ldmd2 could be ported outside of sokol-d using this idea.