.. _program_listing_file_Src_GraphicsEngineVulkan_common_FramebufferHelper.hpp:

Program Listing for File FramebufferHelper.hpp
==============================================

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

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

.. code-block:: cpp

   #pragma once
   
   #include <span>
   #include <vector>
   
   #include <vulkan/vulkan.hpp>
   
   namespace Kataglyphis {
   
   // Every framebuffer in this engine is built from a render pass, a flat list
   // of attachment views, and the target extent - Rasterizer, PostStage,
   // DeferredRasterizer, SkyBox and CascadedShadowMap each spelled out the same
   // five field assignments, and one of the five (SkyBox) had its
   // attachmentCount hard-coded to 2 rather than derived from the array it was
   // handed.
   //
   // attachmentCount is deliberately DERIVED from attachments.size() rather than
   // taken as a parameter, so the count can never drift from the span actually
   // passed in.
   //
   // Lifetime note: the returned vk::FramebufferCreateInfo borrows
   // attachments.data() - it must be consumed by createFramebuffer before the
   // span's backing storage goes out of scope or is mutated for a different
   // framebuffer.
   //
   // A pass that needs an imageless framebuffer or another flag must build the
   // vk::FramebufferCreateInfo inline and say why, rather than growing this
   // helper a parameter - the same rule RenderPassHelper.hpp and
   // ViewportHelper.hpp state, for the same reason.
   //
   // Built via the fully-explicit vk::FramebufferCreateInfo constructor rather
   // than value-init-then-assign: value-init (`vk::FramebufferCreateInfo{}`)
   // defaults every unspecified parameter, including `RenderPass renderPass_ =
   // {}`, and that default expands to RenderPass's non-constexpr default
   // constructor - which would make this function impossible to call in a
   // constant expression no matter what the caller passes.
   constexpr vk::FramebufferCreateInfo buildFramebufferCreateInfo(vk::RenderPass render_pass,
     std::span<const vk::ImageView> attachments,
     vk::Extent2D extent,
     uint32_t layers = 1)
   {
       return vk::FramebufferCreateInfo{ vk::FramebufferCreateFlags{}, render_pass,
           static_cast<uint32_t>(attachments.size()), attachments.data(), extent.width, extent.height, layers };
   }
   
   // Destroys every framebuffer in the vector and clears it, and destroys a
   // single framebuffer and nulls its handle - the same idempotence rule
   // PipelineLayoutHelper.hpp's destroyPipelineAndLayout follows: a device-less
   // call (already torn down, or never had a device) is a no-op rather than a
   // crash, so an explicit cleanUp followed by the destructor's safety net stays
   // safe. The target is taken by reference for the same reason
   // destroyPipelineAndLayout takes its handles by reference; passing by value
   // would destroy without clearing/nulling and leave the caller holding a
   // dangling handle.
   inline void destroyFramebuffers(vk::Device device, std::vector<vk::Framebuffer> &framebuffers)
   {
       if (!device) { return; }
       for (auto &framebuffer : framebuffers) {
           if (framebuffer) { device.destroyFramebuffer(framebuffer); }
       }
       framebuffers.clear();
   }
   
   inline void destroyFramebuffer(vk::Device device, vk::Framebuffer &framebuffer)
   {
       if (!device) { return; }
       if (framebuffer) {
           device.destroyFramebuffer(framebuffer);
           framebuffer = nullptr;
       }
   }
   
   }// namespace Kataglyphis