.. _program_listing_file_Src_GraphicsEngineVulkan_common_PipelineLayoutHelper.hpp:

Program Listing for File PipelineLayoutHelper.hpp
=================================================

|exhale_lsh| :ref:`Return to documentation for file <file_Src_GraphicsEngineVulkan_common_PipelineLayoutHelper.hpp>` (``Src/GraphicsEngineVulkan/common/PipelineLayoutHelper.hpp``)

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

.. code-block:: cpp

   #pragma once
   
   #include <span>
   
   #include <vulkan/vulkan.hpp>
   
   namespace Kataglyphis {
   
   // Every pipeline layout in this engine spelled out the same field
   // assignments by hand, in nine places across eight files: Clouds,
   // Raytracing, SkyBox, Rasterizer, PathTracing, PostStage,
   // CascadedShadowMap and DeferredRasterizer (geometry and lighting).
   // SkyBox hard-coded setLayoutCount = 2 next to a two-element std::array
   // instead of deriving it, exactly as it did for FramebufferHelper.hpp's
   // attachmentCount and RenderPassHelper.hpp's attachmentCount.
   //
   // setLayoutCount and pushConstantRangeCount are both deliberately DERIVED
   // from their span's .size() rather than taken as parameters, so neither can
   // drift from the array actually passed in. The defaulted empty
   // push_constant_ranges span is what lets Clouds and the deferred lighting
   // pass drop their "no push constants" special case entirely.
   //
   // Lifetime note: the returned vk::PipelineLayoutCreateInfo borrows both
   // spans' .data() pointers - they must outlive the createPipelineLayout call
   // that consumes it.
   //
   // flags is deliberately left at its default so a pass that needs one -
   // none does today - assigns it on the returned value rather than this
   // helper growing a parameter, the same rule RenderPassHelper.hpp's and
   // FramebufferHelper.hpp's helpers state.
   //
   // Built via the fully-explicit vk::PipelineLayoutCreateInfo constructor
   // rather than value-init-then-assign, for the same constexpr reason
   // FramebufferHelper.hpp documents.
   constexpr vk::PipelineLayoutCreateInfo buildPipelineLayoutCreateInfo(
     std::span<const vk::DescriptorSetLayout> set_layouts,
     std::span<const vk::PushConstantRange> push_constant_ranges = {})
   {
       return vk::PipelineLayoutCreateInfo{ vk::PipelineLayoutCreateFlags{}, static_cast<uint32_t>(set_layouts.size()),
           set_layouts.data(), static_cast<uint32_t>(push_constant_ranges.size()), push_constant_ranges.data() };
   }
   
   // Destroys a pipeline and the layout it was built with, and nulls both
   // handles so a second call (an explicit cleanUp followed by the
   // destructor) is a no-op - the same idempotence rule VulkanBuffer and
   // VulkanImage follow. Handles are taken by reference for exactly that
   // reason; passing by value would destroy without nulling and the caller
   // would keep a dangling handle.
   inline void destroyPipelineAndLayout(vk::Device device, vk::Pipeline &pipeline, vk::PipelineLayout &layout)
   {
       if (!device) { return; }
       if (pipeline) {
           device.destroyPipeline(pipeline);
           pipeline = nullptr;
       }
       if (layout) {
           device.destroyPipelineLayout(layout);
           layout = nullptr;
       }
   }
   
   }// namespace Kataglyphis