/****************************************************************************
**
** Copyright (C) 2008-2012 NVIDIA Corporation.
** Copyright (C) 2021 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt Quick 3D.
**
** $QT_BEGIN_LICENSE:COMM$
**
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** $QT_END_LICENSE$
**
**
**
**
**
**
**
**
**
****************************************************************************/

#ifndef QSSG_RENDER_SHADOW_MAP_H
#define QSSG_RENDER_SHADOW_MAP_H

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

#include <QtQuick3DRuntimeRender/private/qssgrendercontextcore_p.h>
#include <QtGui/QMatrix4x4>
#include <QtGui/QVector3D>
#include <QtQuick3DRender/private/qssgrenderbasetypes_p.h>

QT_BEGIN_NAMESPACE

struct QSSGLayerRenderData;

enum class ShadowMapModes
{
    SSM, ///< standard shadow mapping
    VSM, ///< variance shadow mapping
    CUBE, ///< cubemap omnidirectional shadows
};

enum class ShadowFilterValues
{
    NONE = 1 << 0, ///< hard shadows
    PCF = 1 << 1, ///< Percentage close filtering
    BLUR = 1 << 2, ///< Gausian Blur
};

struct QSSGShadowMapEntry
{
    QSSGShadowMapEntry()
        : m_lightIndex(std::numeric_limits<quint32>::max())
        , m_shadowMapMode(ShadowMapModes::SSM)
        , m_shadowFilterFlags(ShadowFilterValues::NONE)
    {
    }

    QSSGShadowMapEntry(quint32 index,
                         ShadowMapModes mode,
                         ShadowFilterValues filter,
                         const QSSGRef<QSSGRenderTexture2D> &depthMap,
                         const QSSGRef<QSSGRenderTexture2D> &depthCopy,
                         const QSSGRef<QSSGRenderTexture2D> &depthTemp)
        : m_lightIndex(index)
        , m_shadowMapMode(mode)
        , m_shadowFilterFlags(filter)
        , m_depthMap(depthMap)
        , m_depthCopy(depthCopy)
        , m_depthCube(nullptr)
        , m_cubeCopy(nullptr)
        , m_depthRender(depthTemp)
    {
    }

    QSSGShadowMapEntry(quint32 index,
                         ShadowMapModes mode,
                         ShadowFilterValues filter,
                         const QSSGRef<QSSGRenderTextureCube> &depthCube,
                         const QSSGRef<QSSGRenderTextureCube> &cubeTmp,
                         const QSSGRef<QSSGRenderTexture2D> &depthTemp)
        : m_lightIndex(index)
        , m_shadowMapMode(mode)
        , m_shadowFilterFlags(filter)
        , m_depthMap(nullptr)
        , m_depthCopy(nullptr)
        , m_depthCube(depthCube)
        , m_cubeCopy(cubeTmp)
        , m_depthRender(depthTemp)
    {
    }

    quint32 m_lightIndex; ///< the light index it belongs to
    ShadowMapModes m_shadowMapMode; ///< shadow map method
    ShadowFilterValues m_shadowFilterFlags; ///< shadow filter mode

    // PKC : Adding the DepthRender buffer allows us to have a depth+stencil format when filling
    // the shadow maps (depth+stencil is necessary), but use a more compact format for the
    // actual
    // shadow map used at shade time.  See if it's worth adding.
    QSSGRef<QSSGRenderTexture2D> m_depthMap; ///< shadow map texture
    QSSGRef<QSSGRenderTexture2D> m_depthCopy; ///< shadow map buffer used during blur passes
    QSSGRef<QSSGRenderTextureCube> m_depthCube; ///< shadow cube map
    QSSGRef<QSSGRenderTextureCube> m_cubeCopy; ///< cube map buffer used during the blur passes
    QSSGRef<QSSGRenderTexture2D> m_depthRender; ///< shadow depth+stencil map used during rendering

    QMatrix4x4 m_lightVP; ///< light view projection matrix
    QMatrix4x4 m_lightCubeView[6]; ///< light cubemap view matrices
    QMatrix4x4 m_lightView; ///< light view transform
};

class QSSGRenderShadowMap
{
    typedef QVector<QSSGShadowMapEntry> TShadowMapEntryList;

public:
    QAtomicInt ref;
    QSSGRef<QSSGRenderContextInterface> m_context;

    QSSGRenderShadowMap(const QSSGRef<QSSGRenderContextInterface> &inContext);
    ~QSSGRenderShadowMap();

    /*
     * @brief Add a shadow map entry
     *		  This creates a new shadow map if it does not exist or changed
     *
     * @param[in] index		shadow map entry index
     * @param[in] width		shadow map width
     * @param[in] height	shadow map height
     * @param[in] format	shadow map format
     * @param[in] samples	shadow map sample count
     * @param[in] mode		shadow map mode like SSM, VCM
     * @param[in] filter	soft shadow map mode filter like PCF
     *
     * @ return no return
     */
    void addShadowMapEntry(qint32 index,
                           qint32 width,
                           qint32 height,
                           QSSGRenderTextureFormat format,
                           qint32 samples,
                           ShadowMapModes mode,
                           ShadowFilterValues filter);

    /*
     * @brief Get a shadow map entry
     *
     * @param[in] index		shadow map entry index
     *
     * @ return shadow map entry or nullptr
     */
    QSSGShadowMapEntry *getShadowMapEntry(int index);

    /*
     * @brief Get shadow map entry count
     *
     * @ return count of shadow map entries
     */
    qint32 getShadowMapEntryCount() { return m_shadowMapList.size(); }

    static QSSGRef<QSSGRenderShadowMap> create(const QSSGRef<QSSGRenderContextInterface> &inContext);

private:
    TShadowMapEntryList m_shadowMapList; ///< List of shadow map entries
};
QT_END_NAMESPACE

#endif
