.. _program_listing_file_Src_GraphicsEngineVulkan_renderer_accelerationStructures_BlasGeometryLimits.hpp:

Program Listing for File BlasGeometryLimits.hpp
===============================================

|exhale_lsh| :ref:`Return to documentation for file <file_Src_GraphicsEngineVulkan_renderer_accelerationStructures_BlasGeometryLimits.hpp>` (``Src/GraphicsEngineVulkan/renderer/accelerationStructures/BlasGeometryLimits.hpp``)

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

.. code-block:: cpp

   #pragma once
   
   #include <cstdint>
   #include <span>
   #include <vulkan/vulkan.hpp>
   
   #include "shared/scene/ObjMaterial.hpp"
   
   namespace Kataglyphis {
   struct BlasTriangleLimits {
       uint32_t maxVertex;
       uint32_t primitiveCount;
   };
   
   // maxVertex is the highest addressable vertex index, not the vertex count -
   // passing the count over-declares the buffer by one stride, and
   // robustBufferAccess is off (VulkanDevice::create_logical_device sets
   // robustBufferAccess = VK_FALSE) so nothing clamps the read. The zero-vertex
   // guard matters: without it, an empty mesh would wrap to 0xFFFFFFFF instead
   // of staying 0.
   constexpr BlasTriangleLimits blasTriangleLimits(uint32_t vertexCount, uint32_t indexCount)
   {
       return { vertexCount == 0 ? 0 : vertexCount - 1, indexCount / 3 };
   }
   
   // A mesh needs any-hit invocation (i.e. must not be eOpaque) iff at least one
   // of its materials is a glTF MASK material - see ObjMaterial.hpp's
   // alphaCutoff convention: alphaCutoff >= 0 means MASK, negative means
   // OPAQUE/BLEND. A single MASK material among many OPAQUE ones is enough,
   // since all of a mesh's geometry shares one BLAS geometry entry and one flag.
   constexpr bool blasGeometryNeedsAnyHit(std::span<const ObjMaterial> materials)
   {
       for (const ObjMaterial &material : materials) {
           if (material.alphaCutoff >= 0.0F) { return true; }
       }
       return false;
   }
   
   // eOpaque suppresses any-hit shader invocation entirely, which is the fast
   // path for geometry that has no MASK material to alpha-test. Geometry that
   // does must stay non-opaque so raytrace.rahit.slang's alpha test still runs.
   constexpr vk::GeometryFlagsKHR blasGeometryFlags(bool needsAnyHit)
   {
       return needsAnyHit ? vk::GeometryFlagsKHR{} : vk::GeometryFlagsKHR{ vk::GeometryFlagBitsKHR::eOpaque };
   }
   }// namespace Kataglyphis