/***************************************************************************
  qgsmetalroughmaterial.h
  --------------------------------------
  Date                 : December 2023
  Copyright            : (C) 2023 by Nyall Dawson
  Email                : nyall dot dawson at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef QGSMETALROUGHMATERIAL_H
#define QGSMETALROUGHMATERIAL_H

#include "qgis_3d.h"

#include <Qt3DRender/QMaterial>
#include <QObject>

#define SIP_NO_FILE

// adapted from Qt's qmetalroughmaterial.h
namespace Qt3DRender
{

  class QFilterKey;
  class QEffect;
  class QAbstractTexture;
  class QTechnique;
  class QParameter;
  class QShaderProgram;
  class QShaderProgramBuilder;
  class QRenderPass;

} // namespace Qt3DRender

///@cond PRIVATE

/**
 * \ingroup 3d
 * \brief A PBR metal rough material.
 * \since QGIS 3.36
 */
class _3D_EXPORT QgsMetalRoughMaterial : public Qt3DRender::QMaterial
{
    Q_OBJECT
  public:

    /**
     * Constructor for QgsMetalRoughMaterial, with the specified \a parent node.
     */
    explicit QgsMetalRoughMaterial( Qt3DCore::QNode *parent = nullptr );
    ~QgsMetalRoughMaterial() override;

    QVariant baseColor() const;
    QVariant metalness() const;
    QVariant roughness() const;
    QVariant ambientOcclusion() const;
    QVariant normal() const;
    float textureScale() const;

    /**
     * When flat shading is enabled, we do not use vertex normals from the geometry,
     * and rather generate the normals on the fly in shader code.
     *
     * \note This is especially useful with some GLTF models that do not include normals,
     * and the spec requires the viewer to use flat shading.
     */
    bool flatShadingEnabled() const;

  public slots:
    void setBaseColor( const QVariant &baseColor );
    void setMetalness( const QVariant &metalness );
    void setRoughness( const QVariant &roughness );
    void setAmbientOcclusion( const QVariant &ambientOcclusion );
    void setNormal( const QVariant &normal );
    void setTextureScale( float textureScale );
    void setFlatShadingEnabled( bool enabled );

  signals:
    void baseColorChanged( const QVariant &baseColor );
    void metalnessChanged( const QVariant &metalness );
    void roughnessChanged( const QVariant &roughness );
    void ambientOcclusionChanged( const QVariant &ambientOcclusion );
    void normalChanged( const QVariant &normal );
    void textureScaleChanged( float textureScale );

  private:
    void init();

    void handleTextureScaleChanged( const QVariant &var );
    void updateFragmentShader();

    Qt3DRender::QParameter *mBaseColorParameter = nullptr;
    Qt3DRender::QParameter *mMetalnessParameter = nullptr;
    Qt3DRender::QParameter *mRoughnessParameter = nullptr;
    Qt3DRender::QParameter *mBaseColorMapParameter = nullptr;
    Qt3DRender::QParameter *mMetalnessMapParameter = nullptr;
    Qt3DRender::QParameter *mRoughnessMapParameter = nullptr;
    Qt3DRender::QParameter *mAmbientOcclusionMapParameter = nullptr;
    Qt3DRender::QParameter *mNormalMapParameter = nullptr;
    Qt3DRender::QParameter *mTextureScaleParameter = nullptr;
    Qt3DRender::QEffect *mMetalRoughEffect = nullptr;
    Qt3DRender::QTechnique *mMetalRoughGL3Technique = nullptr;
    Qt3DRender::QRenderPass *mMetalRoughGL3RenderPass = nullptr;
    Qt3DRender::QShaderProgram *mMetalRoughGL3Shader = nullptr;
    Qt3DRender::QFilterKey *mFilterKey = nullptr;
    bool mUsingBaseColorMap = false;
    bool mUsingMetalnessMap = false;
    bool mUsingRoughnessMap = false;
    bool mUsingAmbientOcclusionMap = false;
    bool mUsingNormalMap = false;
    bool mFlatShading = false;

};

///@endcond PRIVATE

#endif // QGSMETALROUGHMATERIAL_H
