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#ifndef QT3DANIMATION_ANIMATION_GLTFIMPORTER_H
#define QT3DANIMATION_ANIMATION_GLTFIMPORTER_H

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists for the convenience
// of other Qt classes.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//

#include <QtGlobal>
#include <Qt3DAnimation/private/fcurve_p.h>
#include <Qt3DRender/qattribute.h>
#include <Qt3DCore/private/sqt_p.h>
#include <Qt3DCore/private/qmath3d_p.h>

#include <QJsonDocument>
#include <QJsonObject>
#include <QJsonArray>
#include <QJsonValue>
#include <QVector>

QT_BEGIN_NAMESPACE

class QIODevice;

namespace Qt3DAnimation {
namespace Animation {

class GLTFImporter
{
public:
    class BufferData
    {
    public:
        BufferData();
        explicit BufferData(const QJsonObject &json);

        quint64 byteLength;
        QString path;
        QByteArray data;
    };

    class BufferView
    {
    public:
        BufferView();
        explicit BufferView(const QJsonObject &json);

        quint64 byteOffset;
        quint64 byteLength;
        int bufferIndex;
        int target; // Only for per vertex attributes
    };

    class AccessorData
    {
    public:
        AccessorData();
        explicit AccessorData(const QJsonObject &json);

        int bufferViewIndex;
        Qt3DRender::QAttribute::VertexBaseType type;
        uint dataSize;
        int count;
        int byteOffset;
        int byteStride; // Only for per vertex attributes

        // TODO: Extend to support sparse accessors
    };

    class Skin
    {
    public:
        Skin();
        explicit Skin(const QJsonObject &json);

        QString name;
        int inverseBindAccessorIndex;
        QVector<int> jointNodeIndices;
    };

    class Channel
    {
    public:
        Channel();
        explicit Channel(const QJsonObject &json);

        int samplerIndex;
        int targetNodeIndex;
        QString targetProperty;
    };

    class Sampler
    {
    public:
        Sampler();
        explicit Sampler(const QJsonObject &json);

        enum InterpolationMode {
            Linear,
            Step,
            CatmullRomSpline,
            CubicSpline
        };

        QString interpolationModeString() const;

        int inputAccessorIndex;
        int outputAccessorIndex;
        InterpolationMode interpolationMode;
    };

    class Animation
    {
    public:
        Animation();
        explicit Animation(const QJsonObject &json);

        QString name;
        QVector<Channel> channels;
        QVector<Sampler> samplers;
    };

    class Node
    {
    public:
        Node();
        explicit Node(const QJsonObject &json);

        Qt3DCore::Sqt localTransform;
        QVector<int> childNodeIndices;
        QString name;
        int parentNodeIndex;
        int cameraIndex;
        int meshIndex;
        int skinIndex;
    };

    GLTFImporter();

    bool load(QIODevice *ioDev);
    const QVector<Animation> animations() const { return m_animations; }

    struct AnimationNameAndChannels
    {
        QString name;
        QVector<Qt3DAnimation::Animation::Channel> channels;
    };
    AnimationNameAndChannels createAnimationData(int animationIndex, const QString &animationName = QString()) const;

private:
    static Qt3DRender::QAttribute::VertexBaseType accessorTypeFromJSON(int componentType);
    static uint accessorTypeSize(Qt3DRender::QAttribute::VertexBaseType componentType);
    static uint accessorDataSizeFromJson(const QString &type);

    struct RawData
    {
        const char *data;
        quint64 byteLength;
    };

    void setBasePath(const QString &path);
    bool setJSON(const QJsonDocument &json);

    bool parse();
    bool parseGLTF2();
    void cleanup();
    QHash<int, int> createNodeIndexToJointIndexMap(const Skin &skin) const;

    bool processJSONBuffer(const QJsonObject &json);
    bool processJSONBufferView(const QJsonObject &json);
    bool processJSONAccessor(const QJsonObject &json);
    bool processJSONSkin(const QJsonObject &json);
    bool processJSONAnimation(const QJsonObject &json);
    bool processJSONNode(const QJsonObject &json);
    void setupNodeParentLinks();
    QByteArray resolveLocalData(const QString &path) const;

    RawData accessorData(int accessorIndex, int index) const;

    QJsonDocument m_json;
    QString m_basePath;
    QVector<BufferData> m_bufferDatas;
    QVector<BufferView> m_bufferViews;
    QVector<AccessorData> m_accessors;
    QVector<Skin> m_skins;
    QVector<Animation> m_animations;
    QVector<Node> m_nodes;
};

} // namespace Animation
} // namespace Qt3DAnimation

QT_END_NAMESPACE

#endif // QT3DANIMATION_ANIMATION_GLTFIMPORTER_H