Crafter.Build/interfaces/Crafter.Build-Asset.cppm

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

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

namespace Crafter {
    // Compress a build-time asset (.png/.obj) into its on-disk
    // SaveCompressed counterpart (.ctex/.cmesh) using Crafter.Asset's
    // library API in-process. Returns "" on success, an error message
    // otherwise (matches Shader::Compile's contract).
    //
    // Real implementation lives in the impl unit and only compiles when
    // CRAFTER_BUILD_HAS_ASSET is defined (i.e. when the build links
    // Crafter.Asset). The bootstrap build.sh produces a stub variant
    // that errors out at runtime if cfg.assets is non-empty — full
    // support requires a self-host rebuild via crafter-build itself,
    // which resolves the Crafter.Asset dep through project.cpp.
    export std::string CompressAsset(const fs::path& input, const fs::path& output);

    // Split a single .obj + .mtl file by material group into per-material
    // .cmesh files, per-unique-albedo .ctex files, and a scene.txt manifest
    // under outDir. All albedo textures are resized to albedoSize × albedoSize
    // before compression (required for a texture_2d_array where all layers
    // must have identical dimensions).
    //
    // scene.txt format (read by the Sponza example at runtime):
    //   <albedoCount>
    //   <meshCount>
    //   <albedoIdx_for_mesh_0>   (-1 = no albedo)
    //   ...
    //
    // Idempotent: returns "" immediately if outDir/scene.txt already exists,
    // so repeated builds skip the expensive split+resize step.
    // Returns "" on success, an error string on failure.
    export std::string BuildOBJBundle(
        const fs::path& objPath,
        const fs::path& mtlPath,
        const fs::path& outDir,
        std::uint16_t   albedoSize = 1024
    );
}