Ahjo.Vulkan.Ktx.Native 0.15.0

Ahjo.Vulkan.Ktx.Native

Raw P/Invoke bindings for Khronos libktx — KTX2 container reading and Basis Universal transcoding — with native runtime binaries included for win-x64 and linux-x64.

The managed surface is generated with ClangSharpPInvokeGenerator from ktx.h at a pinned upstream tag. Nothing is hand-written, so the bindings are a mechanical function of that tag.

using Ahjo.Vulkan.Ktx.Native;

unsafe
{
    ktxTexture2* texture;
    fixed (byte* bytes = ktx2File)
    {
        var rc = Ktx.ktxTexture2_CreateFromMemory(
            bytes, (nuint)ktx2File.Length,
            (uint)ktxTextureCreateFlagBits.KTX_TEXTURE_CREATE_LOAD_IMAGE_DATA_BIT,
            &texture);
        if (rc != ktx_error_code_e.KTX_SUCCESS) { /* handle */ }
    }

    if (Ktx.ktxTexture2_NeedsTranscoding(texture))
    {
        Ktx.ktxTexture2_TranscodeBasis(texture, ktx_transcode_fmt_e.KTX_TTF_BC7_RGBA, 0);
    }

    // texture->vkFormat, ->baseWidth/baseHeight, ->numLevels, ->pData, ->dataSize
    // are now the transcoded result. Upload them with your own resource path.
    Ktx.ktxTexture2_Destroy(texture);
}

What is and is not in the native library

The shipped ktx.dll / libktx.so is built from the pinned upstream tag with tools, tests, docs, the JNI and Python bindings, and both texture uploaders disabled.

Dropping KTX_FEATURE_VK_UPLOAD is the load-bearing choice: this package has no Vulkan dependency at all, and does not reference Ahjo.Vulkan.Native. libktx's own uploader creates its own VkImage and records its own barriers, which is precisely what a consumer that owns its resource pool and its synchronization does not want. The binding's contract ends at "here are transcoded bytes, a vkFormat, and mip offsets"; getting them onto the GPU is the caller's business.

The OpenGL entry points (ktxLoadOpenGL, ktxTexture_GLUpload) are therefore absent from the binary, and are excluded from generation as well — a binding whose only possible outcome is EntryPointNotFoundException is a trap, not a feature.

Platform support

arm64 and macOS are deliberately absent rather than untested. libktx links astc-encoder, whose SIMD backend is selected at compile time, so each RID needs a lane that actually loads the binary and transcodes before it can ship.

The x86-64 binaries require AVX2. That is upstream's default ISA selection for astc-encoder and matches the binaries Khronos publishes, so this package stays on the configuration upstream tests. CPUs older than roughly 2013 are out of scope.

Licensing

libktx is Apache-2.0 (Khronos Group); the bundled Basis Universal transcoder is Apache-2.0 (Binomial LLC). This package's own binding code is MIT, like the rest of the Ahjo.Vulkan repository.