Extend SPIRV reflect API to include more details

[pmatyja]

Currently the SPRIV reflect API for graphics/compute shaders return counts.

typedef struct SDL_ShaderCross_GraphicsShaderResourceInfo
{
    Uint32 num_samplers;                     /**< The number of samplers defined in the shader. */
    Uint32 num_storage_textures;             /**< The number of storage textures defined in the shader. */
    Uint32 num_storage_buffers;              /**< The number of storage buffers defined in the shader. */
    Uint32 num_uniform_buffers;              /**< The number of uniform buffers defined in the shader. */
} SDL_ShaderCross_GraphicsShaderResourceInfo;

typedef struct SDL_ShaderCross_ComputePipelineMetadata
{
    Uint32 num_samplers;                    /**< The number of samplers defined in the shader. */
    Uint32 num_readonly_storage_textures;   /**< The number of readonly storage textures defined in the shader. */
    Uint32 num_readonly_storage_buffers;    /**< The number of readonly storage buffers defined in the shader. */
    Uint32 num_readwrite_storage_textures;  /**< The number of read-write storage textures defined in the shader. */
    Uint32 num_readwrite_storage_buffers;   /**< The number of read-write storage buffers defined in the shader. */
    Uint32 num_uniform_buffers;             /**< The number of uniform buffers defined in the shader. */
    Uint32 threadcount_x;                   /**< The number of threads in the X dimension. */
    Uint32 threadcount_y;                   /**< The number of threads in the Y dimension. */
    Uint32 threadcount_z;                   /**< The number of threads in the Z dimension. */
} SDL_ShaderCross_ComputePipelineMetadata;

It would be very useful if the API would contain more details like:

• name (if exists in SPRIV)
• binding indices (eg. set, binding / register, space)
• anything else that could be useful

eg.

typedef struct SDL_ShaderCross_ReflectResourceInfo
{
    char *name;
    Uint32 set;
    Uint32 binding;
} SDL_ShaderCross_ReflectResourceInfo;

typedef struct SDL_ShaderCross_GraphicsShaderResourceInfo
{
    Uint32 num_samplers;                     /**< The number of samplers defined in the shader. */
    Uint32 num_storage_textures;             /**< The number of storage textures defined in the shader. */
    Uint32 num_storage_buffers;              /**< The number of storage buffers defined in the shader. */
    Uint32 num_uniform_buffers;              /**< The number of uniform buffers defined in the shader. */

    /** new fields */
    SDL_ShaderCross_ReflectResourceInfo   samplers;
    SDL_ShaderCross_ReflectResourceInfo   storage_textures;
    SDL_ShaderCross_ReflectResourceInfo   storage_buffers;
    SDL_ShaderCross_ReflectResourceInfo   uniform_buffers;
} SDL_ShaderCross_GraphicsShaderResourceInfo;

Benefits:

• Ability to validate resource locations / bindings
• Automatic resource binding (especially important during development/experimentation for faster iteration time)

[ThomasFOG]

I would also vouch for more reflection data (bindings, names, slots, offsets, buffer sizes, sampler types...), even if it's just SPIRV-reflect or dxc -Fc output.

That would make writing an "effect framework" more convenient, or stuff like nodal shader editors.

I made my own reflector (SPIRV is rather straightforward to parse and reflect) but thought "ah, that would be cool to have directly in ShaderCross". (I unfortunately can't upstream it as I made it in C# as a post-process.)

[Zylann]

I would like to have more reflected information as well, to recognize what the shader exposes so my app can automatically assign the right data to the right bindings/locations (I compile/hot-reload shaders at runtime).

Since I'm currently using SPIRV as the common source format, I'm considering to get information about uniforms etc using SPIRV-reflect, before passing the SPIRV to ShaderCross for eventual translation. Is it actually fine to do that?