/*

Open Asset Import Library (assimp)

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*/

/** @file  MakeLeftHandedProcess.h

 *  @brief Defines a bunch of post-processing steps to handle

 *    coordinate system conversions.

 *

 *  - LH to RH

 *  - UV origin upper-left to lower-left

 *  - face order cw to ccw

 */

#ifndef AI_CONVERTTOLHPROCESS_H_INC

#define AI_CONVERTTOLHPROCESS_H_INC

#include <assimp/types.h>

#include "Common/BaseProcess.h"

struct aiMesh;

struct aiNodeAnim;

struct aiNode;

struct aiMaterial;

struct aiCamera;

namespace Assimp {

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

/** @brief The MakeLeftHandedProcess converts all imported data to a left-handed

 *   coordinate system.

 *

 * This implies a mirroring of the Z axis of the coordinate system. But to keep

 * transformation matrices free from reflections we shift the reflection to other

 * places. We mirror the meshes and adapt the rotations.

 *

 * @note RH-LH and LH-RH is the same, so this class can be used for both

 */

class MakeLeftHandedProcess final : public BaseProcess {

public:

    MakeLeftHandedProcess() = default;

    ~MakeLeftHandedProcess() override = default;

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

    bool IsActive( unsigned int pFlags) const override;

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

    void Execute( aiScene* pScene) override;

protected:

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

    /** Recursively converts a node and all of its children

     */

    void ProcessNode( aiNode* pNode, const aiMatrix4x4& pParentGlobalRotation);

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

    /** Converts a single mesh to left handed coordinates.

     * This means that positions, normals and tangents are mirrored at

     * the local Z axis and the order of all faces are inverted.

     * @param pMesh The mesh to convert.

     */

    void ProcessMesh( aiMesh* pMesh);

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

    /** Converts a single material to left-handed coordinates

     * @param pMat Material to convert

     */

    void ProcessMaterial( aiMaterial* pMat);

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

    /** Converts the given animation to LH coordinates.

     * The rotation and translation keys are transformed, the scale keys

     * work in local space and can therefore be left untouched.

     * @param pAnim The bone animation to transform

     */

    void ProcessAnimation( aiNodeAnim* pAnim);

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

    /** Converts a single camera to left handed coordinates.

     * The camera viewing direction is inverted by reflecting mLookAt

     * across mPosition.

     * @param pCam The camera to convert

     */

    void ProcessCamera( aiCamera* pCam);

};

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

/** Postprocessing step to flip the face order of the imported data

 */

class FlipWindingOrderProcess : public BaseProcess {

    friend class Importer;

public:

    /** Constructor to be privately used by Importer */

    FlipWindingOrderProcess() = default;

    /** Destructor, private as well */

    ~FlipWindingOrderProcess() override = default;

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

    bool IsActive( unsigned int pFlags) const override;

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

    void Execute( aiScene* pScene) override;

    /** Some other types of post-processing require winding order flips */

    static void ProcessMesh( aiMesh* pMesh);

};

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

/** Postprocessing step to flip the UV coordinate system of the import data

 */

class FlipUVsProcess final : public BaseProcess

{

    friend class Importer;

public:

    /** Constructor to be privately used by Importer */

    FlipUVsProcess();

    /** Destructor, private as well */

    ~FlipUVsProcess() override;

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

    bool IsActive( unsigned int pFlags) const override;

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

    void Execute( aiScene* pScene) override;

protected:

    void ProcessMesh( aiMesh* pMesh);

    void ProcessMaterial( aiMaterial* mat);

};

} // end of namespace Assimp

#endif // AI_CONVERTTOLHPROCESS_H_INC