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/// @file SplitByBoneCountProcess.h
/// Defines a post processing step to split meshes with many bones into submeshes
#ifndef AI_SPLITBYBONECOUNTPROCESS_H_INC
#define AI_SPLITBYBONECOUNTPROCESS_H_INC

#include <vector>
#include "Common/BaseProcess.h"

#include <assimp/mesh.h>
#include <assimp/scene.h>

namespace Assimp {

/** Postprocessing filter to split meshes with many bones into submeshes
 * so that each submesh has a certain max bone count.
 *
 * Applied BEFORE the JoinVertices-Step occurs.
 * Returns NON-UNIQUE vertices, splits by bone count.
*/
class SplitByBoneCountProcess : public BaseProcess {
public:
    // -------------------------------------------------------------------
    /// The default class constructor / destructor.
    SplitByBoneCountProcess();
    ~SplitByBoneCountProcess() override = default;

    /// @brief Returns whether the processing step is present in the given flag.
    /// @param pFlags The processing flags the importer was called with. A
    ///        bitwise combination of #aiPostProcessSteps.
    /// @return true if the process is present in this flag fields, false if not.
    bool IsActive( unsigned int pFlags) const override;

    /// @brief Called prior to ExecuteOnScene().
    /// The function is a request to the process to update its configuration
    /// basing on the Importer's configuration property list.
    void SetupProperties(const Importer* pImp) override;

    /// @brief Will return the maximal number of bones.
    /// @return The maximal number of bones.
    size_t getMaxNumberOfBones() const;

protected:
    /// Executes the post processing step on the given imported data.
    /// At the moment a process is not supposed to fail.
    /// @param pScene The imported data to work at.
    void Execute( aiScene* pScene) override;

    /// Splits the given mesh by bone count.
    /// @param pMesh the Mesh to split. Is not changed at all, but might be superfluous in case it was split.
    /// @param poNewMeshes Array of submeshes created in the process. Empty if splitting was not necessary.
    void SplitMesh( const aiMesh* pMesh, std::vector<aiMesh*>& poNewMeshes) const;

    /// Recursively updates the node's mesh list to account for the changed mesh list
    void UpdateNode( aiNode* pNode) const;

private:
    /// Max bone count. Splitting occurs if a mesh has more than that number of bones.
    size_t mMaxBoneCount;

    /// Per mesh index: Array of indices of the new submeshes.
    using IndexArray = std::vector<unsigned int>;
    std::vector<IndexArray> mSubMeshIndices;
};

inline size_t SplitByBoneCountProcess::getMaxNumberOfBones() const {
    return mMaxBoneCount;
}

} // end of namespace Assimp

#endif // !!AI_SPLITBYBONECOUNTPROCESS_H_INC
