.. _program_listing_file_Src_GraphicsEngineVulkan_vulkan_base_SamplerBuilder.ixx:

Program Listing for File SamplerBuilder.ixx
===========================================

|exhale_lsh| :ref:`Return to documentation for file <file_Src_GraphicsEngineVulkan_vulkan_base_SamplerBuilder.ixx>` (``Src/GraphicsEngineVulkan/vulkan_base/SamplerBuilder.ixx``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   module;
   
   #include <cstdint>
   #include <optional>
   #include <span>
   #include <vulkan/vulkan.hpp>
   
   export module kataglyphis.vulkan.sampler_builder;
   
   export namespace Kataglyphis {
   
   // Convenience wrapper over the GltfSamplerDesc overload below for callers
   // that only need one filter/address mode shared across mag, min and U/V/W.
   // Returns the struct only - it does not create the sampler, since the three
   // call sites use three different createSampler overloads and error
   // conventions.
   auto buildSamplerCreateInfo(vk::Filter filter,
     vk::SamplerAddressMode addressMode,
     float maxLod,
     vk::Bool32 anisotropyEnable,
     float maxAnisotropy,
     vk::BorderColor borderColor,
     vk::Bool32 compareEnable = VK_FALSE,
     vk::CompareOp compareOp = vk::CompareOp::eNever) -> vk::SamplerCreateInfo;
   
   struct GltfSamplerDesc
   {
       vk::SamplerAddressMode addressModeU{ vk::SamplerAddressMode::eRepeat };
       vk::SamplerAddressMode addressModeV{ vk::SamplerAddressMode::eRepeat };
       vk::Filter magFilter{ vk::Filter::eLinear };
       vk::Filter minFilter{ vk::Filter::eLinear };
       vk::SamplerMipmapMode mipmapMode{ vk::SamplerMipmapMode::eLinear };
   
       bool operator==(const GltfSamplerDesc &) const = default;
   };
   
   // The primitive form, sourced from a glTF sampler description: mag/min
   // filter and mipmap mode vary independently instead of sharing one
   // `filter`, and U/V wrap modes can differ (W is not a glTF concept for a 2D
   // texture, so it follows U). The overload above delegates here.
   auto buildSamplerCreateInfo(const GltfSamplerDesc &desc,
     float maxLod,
     vk::Bool32 anisotropyEnable,
     float maxAnisotropy,
     vk::BorderColor borderColor,
     vk::Bool32 compareEnable = VK_FALSE,
     vk::CompareOp compareOp = vk::CompareOp::eNever) -> vk::SamplerCreateInfo;
   
   // True when `desc` asked for nearest filtering anywhere (mag, min or mip).
   // Anisotropic filtering is meaningless combined with nearest sampling, and
   // nearest-filtered assets are exactly the ones whose blocky look the author
   // chose deliberately - so anisotropy must not silently apply anyway.
   auto usesNearestFiltering(const GltfSamplerDesc &desc) -> bool;
   
   // Key a created sampler is reusable under: mip level AND glTF sampler
   // description must both match, since two textures with the same mip count
   // but different wrap/filter settings need genuinely different samplers.
   struct SamplerKey
   {
       uint32_t mipLevel;
       GltfSamplerDesc desc;
   
       bool operator==(const SamplerKey &) const = default;
   };
   
   // Looks up an already-created sampler by SamplerKey so callers with several
   // textures that only differ by neither mip level nor sampler description can
   // reuse one vk::Sampler instead of allocating a duplicate per texture. Pure
   // and device-free, so it is unit-testable without a Vulkan instance.
   auto findSampler(std::span<const SamplerKey> createdSamplers, SamplerKey key) -> std::optional<std::size_t>;
   
   }// namespace Kataglyphis