125 lines
3.5 KiB
C++
125 lines
3.5 KiB
C++
#ifndef ARE_INCLUDE_CORE_BVH_H
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#define ARE_INCLUDE_CORE_BVH_H
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#include "basic/types.h"
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#include "scene/mesh.h"
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#include "resource/buffer.h"
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#include <vector>
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#include <memory>
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namespace are {
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/// @brief Axis-aligned bounding box
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struct AABB {
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Vec3 min_;
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Vec3 max_;
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/// @brief Construct AABB from min and max points
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AABB(const Vec3& min = Vec3(0.0f), const Vec3& max = Vec3(0.0f))
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: min_(min), max_(max) {}
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/// @brief Expand AABB to include point
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void expand(const Vec3& point);
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/// @brief Expand AABB to include another AABB
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void expand(const AABB& other);
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/// @brief Get center of AABB
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Vec3 center() const { return (min_ + max_) * 0.5f; }
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/// @brief Get surface area of AABB
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float surface_area() const;
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/// @brief Check if AABB is valid
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bool is_valid() const;
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};
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/// @brief Triangle primitive for BVH
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struct Triangle {
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Vec3 v0_, v1_, v2_;
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Vec3 n0_, n1_, n2_;
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Vec2 uv0_, uv1_, uv2_;
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uint material_id_;
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/// @brief Get bounding box of triangle
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AABB get_bounds() const;
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/// @brief Get centroid of triangle
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Vec3 get_centroid() const;
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};
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/// @brief BVH node for GPU
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struct BVHNode {
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Vec3 aabb_min_;
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uint left_first_; // Left child index or first primitive index
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Vec3 aabb_max_;
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uint count_; // 0 for interior node, >0 for leaf node
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};
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/// @brief Bounding Volume Hierarchy for ray tracing acceleration
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class BVH {
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public:
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/// @brief Constructor
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BVH();
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/// @brief Destructor
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~BVH();
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/// @brief Build BVH from meshes
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/// @param meshes Mesh list
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/// @return True if build succeeded
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bool build(const std::vector<std::shared_ptr<Mesh>>& meshes);
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/// @brief Upload BVH to GPU
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/// @param node_buffer Buffer for BVH nodes
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/// @param triangle_buffer Buffer for triangles
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/// @return True if upload succeeded
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bool upload_to_gpu(Buffer& node_buffer, Buffer& triangle_buffer);
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/// @brief Get total node count
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/// @return Node count
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uint get_node_count() const { return static_cast<uint>(nodes_.size()); }
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/// @brief Get total triangle count
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/// @return Triangle count
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uint get_triangle_count() const { return static_cast<uint>(triangles_.size()); }
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/// @brief Clear BVH data
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void clear();
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private:
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std::vector<BVHNode> nodes_;
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std::vector<Triangle> triangles_;
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std::vector<uint> triangle_indices_;
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/// @brief Recursively build BVH
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/// @param node_idx Current node index
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/// @param first_prim First primitive index
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/// @param prim_count Primitive count
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void build_recursive_(uint node_idx, uint first_prim, uint prim_count);
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/// @brief Find best split using SAH
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/// @param first_prim First primitive index
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/// @param prim_count Primitive count
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/// @param axis Split axis (output)
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/// @param split_pos Split position (output)
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/// @return Split cost
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float find_best_split_(uint first_prim, uint prim_count, int& axis, float& split_pos);
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/// @brief Calculate node bounds
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/// @param first_prim First primitive index
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/// @param prim_count Primitive count
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/// @return Bounding box
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AABB calculate_bounds_(uint first_prim, uint prim_count);
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/// @brief Calculate centroid bounds
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/// @param first_prim First primitive index
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/// @param prim_count Primitive count
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/// @return Centroid bounding box
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AABB calculate_centroid_bounds_(uint first_prim, uint prim_count);
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};
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} // namespace are
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#endif // ARE_INCLUDE_CORE_BVH_H
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