/*

Open Asset Import Library (assimp)

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*/

/** @file  OptimizeMeshes.h

 *  @brief Declares a post processing step to join meshes, if possible

 */

#ifndef AI_OPTIMIZEMESHESPROCESS_H_INC

#define AI_OPTIMIZEMESHESPROCESS_H_INC

#include "Common/BaseProcess.h"

#include <assimp/types.h>

#include <vector>

struct aiMesh;

struct aiNode;

class OptimizeMeshesProcessTest;

namespace Assimp {

// ---------------------------------------------------------------------------

/** @brief Postprocessing step to optimize mesh usage

 *

 *  The implementation looks for meshes that could be joined and joins them.

 *  Usually this will reduce the number of drawcalls.

 *

 *  @note Instanced meshes are currently not processed.

 */

class OptimizeMeshesProcess : public BaseProcess {

public:

    // -------------------------------------------------------------------

    /// The default class constructor / destructor.

    OptimizeMeshesProcess();

    ~OptimizeMeshesProcess() override = default;

    /** @brief Internal utility to store additional mesh info

     */

    struct MeshInfo {

        MeshInfo() AI_NO_EXCEPT

        : instance_cnt(0)

        , vertex_format(0)

        , output_id(0xffffffff) {

            // empty

        }

        //! Number of times this mesh is referenced

        unsigned int instance_cnt;

        //! Vertex format id

        unsigned int vertex_format;

        //! Output ID

        unsigned int output_id;

    };

    // -------------------------------------------------------------------

    bool IsActive( unsigned int pFlags) const override;

    // -------------------------------------------------------------------

    void Execute( aiScene* pScene) override;

    // -------------------------------------------------------------------

    void SetupProperties(const Importer* pImp) override;

    // -------------------------------------------------------------------

    /** @brief Specify whether you want meshes with different

     *   primitive types to be merged as well.

     *

     *  IsActive() sets this property automatically to true if the

     *  aiProcess_SortByPType flag is found.

     */

    void EnablePrimitiveTypeSorting(bool enable) {

        pts = enable;

    }

    // Getter

    bool IsPrimitiveTypeSortingEnabled () const {

        return pts;

    }

    // -------------------------------------------------------------------

    /** @brief Specify a maximum size of a single output mesh.

     *

     *  If a single input mesh already exceeds this limit, it won't

     *  be split.

     *  @param verts Maximum number of vertices per mesh

     *  @param faces Maximum number of faces per mesh

     */

    void SetPreferredMeshSizeLimit (unsigned int verts, unsigned int faces)

    {

        max_verts = verts;

        max_faces = faces;

    }

protected:

    // -------------------------------------------------------------------

    /** @brief Do the actual optimization on all meshes of this node

     *  @param pNode Node we're working with

     */

    void ProcessNode( aiNode* pNode);

    // -------------------------------------------------------------------

    /** @brief Returns true if b can be joined with a

     *

     *  @param verts Number of output verts up to now

     *  @param faces Number of output faces up to now

     */

    bool CanJoin ( unsigned int a, unsigned int b,

        unsigned int verts, unsigned int faces );

    // -------------------------------------------------------------------

    /** @brief Find instanced meshes, for the moment we're excluding

     *   them from all optimizations

     */

    void FindInstancedMeshes (aiNode* pNode);

private:

    //! Scene we're working with

    aiScene* mScene;

    //! Per mesh info

    std::vector<MeshInfo> meshes;

    //! Output meshes

    std::vector<aiMesh*> output;

    //! @see EnablePrimitiveTypeSorting

    mutable bool pts;

    //! @see SetPreferredMeshSizeLimit

    mutable unsigned int max_verts,max_faces;

    //! Temporary storage

    std::vector<aiMesh*> merge_list;

};

} // end of namespace Assimp

#endif // AI_CALCTANGENTSPROCESS_H_INC