TWideBvhNode.h

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#pragma once
 
#include "Math/Geometry/TAABB3D.h"
#include "Math/constant.h"
#include "Utility/TSpan.h"
 
#include <Common/primitive_type.h>
#include <Common/utility.h>
#include <Common/compiler.h>
#include <Common/memory.h>
 
#include <cstddef>
#include <type_traits>
#include <array>
#include <algorithm>
 
namespace ph::math
{
 
template<std::size_t N, typename Index>
class TWideBvhNode final
{
    static_assert(N >= 2);
    static_assert(std::is_unsigned_v<Index>);
 
    inline static constexpr std::size_t NUM_ITEMS_BITS = 5;
 
    inline static constexpr uint8 X_AXIS_FLAG  = 0b00;
    inline static constexpr uint8 Y_AXIS_FLAG  = 0b01;
    inline static constexpr uint8 Z_AXIS_FLAG  = 0b10;
    inline static constexpr uint8 NO_AXIS_FLAG = 0b11;
 
    static_assert(constant::X_AXIS == X_AXIS_FLAG);
    static_assert(constant::Y_AXIS == Y_AXIS_FLAG);
    static_assert(constant::Z_AXIS == Z_AXIS_FLAG);
 
public:
    inline static constexpr std::size_t MAX_NODE_ITEMS = (std::size_t(1) << NUM_ITEMS_BITS) - 1;
 
    inline static constexpr std::size_t SOA_VIEW_ALIGNMENT = std::clamp(
        N * 4, std::size_t(16), std::size_t(64));
 
    TWideBvhNode();
 
    AABB3D getAABB(std::size_t childIdx) const;
    bool isLeaf(std::size_t childIdx) const;
    bool isInternal(std::size_t childIdx) const;
    std::size_t getChildOffset(std::size_t childIdx) const;
 
    TSpanView<real, N> getMinVerticesOnAxis(std::size_t axis) const;
    TSpanView<real, N> getMaxVerticesOnAxis(std::size_t axis) const;
 
    std::size_t getSplitAxis(std::size_t childIdx) const;
    
    std::size_t getItemOffset(std::size_t childIdx) const;
    std::size_t numItems(std::size_t childIdx) const;
 
    TWideBvhNode& setInternal(
        std::size_t childIdx,
        const AABB3D& childAABB,
        std::size_t childOffset,
        std::size_t splitAxis);
 
    TWideBvhNode& setLeaf(
        std::size_t childIdx,
        const AABB3D& childAABB,
        std::size_t itemOffset,
        std::size_t splitAxis,
        std::size_t numItems);
 
    TWideBvhNode& setEmptyLeaf(
        std::size_t childIdx,
        std::size_t splitAxis);
 
private:
    struct ChildData
    {
        uint8 isLeaf : 1 = true;
        uint8 splitAxis : 2 = NO_AXIS_FLAG;
        uint8 numItems : NUM_ITEMS_BITS = 0;
    };
 
    static_assert(sizeof(ChildData) == sizeof(uint8));
 
    TAlignedArray<std::array<real, N>, 3, SOA_VIEW_ALIGNMENT> m_aabbMins;
    TAlignedArray<std::array<real, N>, 3, SOA_VIEW_ALIGNMENT> m_aabbMaxs;
 
    std::array<Index, N> m_offsets;
 
    std::array<ChildData, N> m_childrenData;
};
 
}// end namespace ph::math
 
#include "Math/Algorithm/BVH/TWideBvhNode.ipp"