BVHTree.h

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// Copyright © 2008-2023 Pioneer Developers. See AUTHORS.txt for details
// Licensed under the terms of the GPL v3. See licenses/GPL-3.txt
 
#ifndef _BVHTREE_H
#define _BVHTREE_H
 
#include "../Aabb.h"
#include "../utils.h"
#include "../vector3.h"
#include <assert.h>
#include <vector>
 
struct BVHNode {
    Aabb aabb;
 
    /* if triIndicesStart == 0 then not leaf,
     * kids[] valid */
    int numTris;
    int *triIndicesStart;
 
    BVHNode *kids[2];
 
    BVHNode() :
        numTris(0),
        triIndicesStart(nullptr)
    {
        kids[0] = nullptr;
        kids[1] = nullptr;
    }
    bool IsLeaf() const
    {
        return triIndicesStart != nullptr;
    }
};
 
class BVHTree {
public:
    typedef int objPtr_t;
    BVHTree(const int numObjs, const objPtr_t *objPtrs, const Aabb *objAabbs);
    ~BVHTree()
    {
        delete[] m_objPtrAlloc;
        delete[] m_bvhNodes;
    }
    BVHNode *GetRoot() { return m_root; }
 
private:
    void BuildNode(BVHNode *node,
        const objPtr_t *objPtrs,
        const Aabb *objAabbs,
        std::vector<objPtr_t> &activeObjIdxs);
    void MakeLeaf(BVHNode *node, const objPtr_t *objPtrs, std::vector<objPtr_t> &objs);
    BVHNode *AllocNode()
    {
        if (m_nodeAllocPos >= m_nodeAllocMax) Error("Out of space in m_bvhNodes.");
        return &m_bvhNodes[m_nodeAllocPos++];
    }
    BVHNode *m_root;
    objPtr_t *m_objPtrAlloc;
    size_t m_objPtrAllocPos;
    size_t m_objPtrAllocMax;
 
    BVHNode *m_bvhNodes;
    size_t m_nodeAllocPos;
    size_t m_nodeAllocMax;
};
 
#endif /* _BVHTREE_H */