hlsl -> spirv -> glsl compilation lost texture binding points

[Hochheilige]

Hello!
I decided to write shaders in hlsl to use it with my OpenGl render. My fragment shader has following textures and sampler

Texture2D<float4> diffuse_map : register(t0, space0);
Texture2D<float4> specular_map : register(t1, space0);
SamplerState samplerState : register(s0, space0);

Using dxc I compile this shader to spirv and want to generate OpenGL readable glsl code using spirv_cross. But for some reason finall glsl code lost the binding points and a space (but this is not so important for ogl). So after generating glsl I have something like this:

uniform Sampler2D _113;
uniform Sampler2D _115;

I use dxc and spirv_cross from my c++ code to compile shaders at runtime and have an ability to recompile it. For dxc I pass only -spirv argument, for spirv_cross I do something like this:

    spirv_cross::CompilerGLSL glsl_compiler(spirv);
    spirv_cross::CompilerGLSL::Options options;
    options.version = 450;
    options.es = false;   
    glsl_compiler.set_common_options(options);
    glsl_compiler.build_combined_image_samplers();
    std::string glsl_code = glsl_compiler.compile();

And as far as I understand build_combined_image_samplers generates this two uniforms from my textures and sampler, but why there is no bindings points at final output and is it possible to generate bindings?

[cdavis5e]

why there is no bindings points at final output?

Normally, that happens because OpenGL below 4.2 requires the GL_ARB_explicit_uniform_location and GL_ARB_shading_language_420pack extensions for that. But, you're setting version to 450 explicitly, and enable_420pack_extension is true by default, so that can't be it.

In this case, I'd say it's because those uniforms are generated by SPIRV-Cross, but SPIRV-Cross didn't copy the DecorationBinding from the original uniforms. And how could it? The original image and sampler uniforms each have a different binding; which one should it copy? What about in the case where multiple images are used with multiple samplers? What if the image and sampler are from different descriptor sets (Vulkan)/register spaces (D3D12/HLSL)?

is it possible to generate bindings?

Yes, but it's somewhat involved. It entails finding the generated uniforms after build_combined_image_samplers() has been called, and explicitly setting DecorationBinding on them. The Compiler::get_shader_resources() and Compiler::set_decoration() methods will facilitate this. This should happen, of course, before compile() is called.

[Hochheilige]

I see. Thank you.
Your solution works for me. I used set_decoration and successfully add bindings to my samplers.