Crafter.Build/interfaces/Crafter.Build-Shader.cppm

// SPDX-License-Identifier: LGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®

export module Crafter.Build:Shader;
import std;
namespace fs = std::filesystem;

namespace Crafter {
    export enum class ShaderType {
        Vertex,
        TessControl,
        TessEvaluation,
        Geometry,
        Fragment,
        Compute,
        RayGen,
        Intersect,
        AnyHit,
        ClosestHit,
        Miss,
        Callable,
        Task,
        Mesh,
    };

    export class Shader {
    public:
        fs::path path;
        std::string entrypoint;
        ShaderType type;
        // Preprocessor macros for this compile, spelled like the compiler's -D:
        // "NAME" (defined to 1) or "NAME=VALUE". They are placed ahead of the
        // source, so one file can be registered more than once and take a
        // different #ifdef branch each time. Note the spelling differs from
        // Configuration::defines, which is a list of {name, value} pairs.
        std::vector<std::string> defines;
        // Names the output when one source is compiled more than once: empty
        // gives "<name>.spv", "sets" gives "<name>.sets.spv". One file-name
        // component: no path separators. Every entry of a configuration must
        // end up with its own OutputName(); Build() fails if two collide, so
        // each extra compile of a source needs its own variant.
        std::string variant;
        Shader(fs::path&& path, std::string&& entrypoint, ShaderType type);
        // File name of the compiled SPIR-V, relative to the output directory.
        // The single source of truth for it: Check, Compile and the artifact
        // forwarding in Build() all go through here.
        fs::path OutputName() const;
        // Whether the output in `outputDir` is up to date: newer than the
        // source and than every file the source #included, and compiled with
        // this entry's stage, entry point and defines, searching
        // `includeDirs`. Compile records the last two in `buildDir`; without
        // its record an output is stale.
        bool Check(const fs::path& outputDir, const fs::path& buildDir, std::span<const fs::path> includeDirs) const;
        // Compiles into `outputDir`, searching `includeDirs` for #include, and
        // records what Check needs in `buildDir`: a depfile naming the source
        // and every file it included, and the settings it was compiled with.
        // Returns an error message, empty on success.
        std::string Compile(const fs::path& outputDir, const fs::path& buildDir, std::span<const fs::path> includeDirs) const;
    };
}