there is a way to get MTLRenderPassDescriptor ?

[coco875]

there is a safe and correct way to get MTLRenderPassDescriptor from MTSwapChain in cpp ?

[coco875]

to be more precise it's to use with ImGui_ImplMetal_NewFrame.
And also similar question for MTLRenderCommandEncoder for ImGui_ImplMetal_RenderDrawData. (this one I am less sure about if need to create it or to get it)

[coco875]

a solution possible is to use https://developer.apple.com/metal/cpp/ but it will add a dependancies for macos.

[LukasBanana]

Sorry I saw your post earlier but forgot to respond.

there is a safe and correct way to get MTLRenderPassDescriptor from MTSwapChain in cpp ?

LLGL currently does not expose this descriptor not even through the native handle interface. I see that ImGui_ImplDX11_NewFrame() doesn't require any additional information, but the Metal version does.
I started creating a separate repository with a dependency to ImGui to have a better foundation to test ImGui support in LLGL.
In the meantime, you can try to create a texture with LLGL that you can render into, then get the native handle via LLGL::Resource::GetNativeHandle() and feed that into your custom MTLRenderPassDescriptor. You can create such a descriptor in a separate source file that is compiled with Objective-C++, i.e. that ends with .mm instead of .cpp/.cxx. Once you rendered successfully into that texture, you can render that texture with a fullscreen pass into the swap-chain.

a solution possible is to use https://developer.apple.com/metal/cpp/ but it will add a dependancies for macos.

That doesn't solve the problem that this descriptor is currently not exposed in the LLGL interface and it would also create a dependency which I want to avoid to keep LLGL lightweight. All it does is help you avoid mixing C++ with Objective-C, but Objective-C++ can already be used for interoperability. While I wouldn't recommend writing a whole project with Objective-C++, it definitely makes life easier to connect the two languages without adding wrapper libraries.

[coco875]

I am very far to know how metal work, I don't practice so much gpu in general, only a little of wgpu. So don't see what I should do exactly.

and for metal-cpp it's just to use c++ and avoid void*, but if you know and are confortable with objective-C++, then there is no problem.

[LukasBanana]

@coco875 I started with a new repository to better explore the use of LLGL with ImGui: https://github.com/LukasBanana/LLGL-Example-ImGui
I started with D3D11 and D3D12 but will continue with Metal next.

[coco875]

ok thanks.

[LukasBanana]

@coco875 I had to add some missing native interfaces to Metal::CommandBufferNativeHandle (see fa52327), but with 79e879b the Metal backend works now with ImGui 🎉

[coco875]

great, I will see it when I have time. Alway apprieciate your help (not against also have an example of integration with vulkan).

[LukasBanana]

Vulkan backend is now also available in LLGL-Example-ImGui (LukasBanana/LLGL-Example-ImGui@1508e71). This also requires a small change in LLGL (7a66865).

[coco875]

Thanks, I will take a look (maybe it can good to replace the old imgui example with this one who are more complete).