#include "nmVTKPlanarScaleGridLayer.h"

#include <QByteArray>
#include <QCoreApplication>
#include <QThread>

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkCellArray.h>
#include <vtkMath.h>
#include <vtkObjectFactory.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkPropAssembly.h>
#include <vtkProperty.h>
#include <vtkProperty2D.h>
#include <vtkRenderer.h>
#include <vtkTextActor.h>
#include <vtkTextProperty.h>
#include <vtkViewport.h>

#include <cstddef>
#include <cmath>
#include <vector>

namespace {

const double PLANAR_AXIS_DEPTH_FACTOR = 0.00020;
const double PLANAR_GRID_DEPTH_FACTOR = 0.00050;
const double PLANAR_BACKGROUND_DEPTH_FACTOR = 0.00100;
const double PLANAR_CAMERA_SIDE_TOLERANCE_FACTOR = 0.000001;
const double PLANAR_EDGE_SWITCH_PIXEL_TOLERANCE = 2.0;
const double PLANAR_TICK_LENGTH_FACTOR = 0.012;
const int PLANAR_LABEL_PIXEL_GAP = 8;
const int PLANAR_CORNER_LABEL_PIXEL_SHIFT = 12;
const int PLANAR_TARGET_INTERVAL_COUNT = 6;

bool isPlanarScaleGridGuiThread()
{
    QCoreApplication* pApplication = QCoreApplication::instance();
    return pApplication == nullptr ||
            pApplication->thread() == QThread::currentThread();
}

bool isValidPlanarBounds(double dXMinimum,
                         double dXMaximum,
                         double dYMinimum,
                         double dYMaximum,
                         double dPlaneZ)
{
    return vtkMath::IsFinite(dXMinimum) &&
            vtkMath::IsFinite(dXMaximum) &&
            vtkMath::IsFinite(dYMinimum) &&
            vtkMath::IsFinite(dYMaximum) &&
            vtkMath::IsFinite(dPlaneZ) &&
            dXMinimum < dXMaximum && dYMinimum < dYMaximum;
}

void appendLine(vtkPoints* pPoints,
                vtkCellArray* pLines,
                double dX1,
                double dY1,
                double dZ1,
                double dX2,
                double dY2,
                double dZ2)
{
    if(pPoints == nullptr || pLines == nullptr) {
        return;
    }
    vtkIdType nPointIds[2];
    nPointIds[0] = pPoints->InsertNextPoint(dX1, dY1, dZ1);
    nPointIds[1] = pPoints->InsertNextPoint(dX2, dY2, dZ2);
    pLines->InsertNextCell(2, nPointIds);
}

void applyLineData(vtkPolyData* pPolyData,
                   vtkPoints* pPoints,
                   vtkCellArray* pLines)
{
    if(pPolyData == nullptr || pPoints == nullptr || pLines == nullptr) {
        return;
    }
    pPolyData->SetPoints(pPoints);
    pPolyData->SetLines(pLines);
    pPolyData->Modified();
}

void applySurfaceData(vtkPolyData* pPolyData,
                      vtkPoints* pPoints,
                      vtkCellArray* pPolygons)
{
    if(pPolyData == nullptr || pPoints == nullptr || pPolygons == nullptr) {
        return;
    }
    pPolyData->SetPoints(pPoints);
    pPolyData->SetPolys(pPolygons);
    pPolyData->Modified();
}

void updatePolyDataZ(vtkPolyData* pPolyData, double dZ)
{
    vtkPoints* pPoints = pPolyData != nullptr
            ? pPolyData->GetPoints() : nullptr;
    if(pPoints == nullptr) {
        return;
    }

    double dPoint[3];
    const vtkIdType nPointCount = pPoints->GetNumberOfPoints();
    for(vtkIdType nPoint = 0; nPoint < nPointCount; ++nPoint) {
        pPoints->GetPoint(nPoint, dPoint);
        dPoint[2] = dZ;
        pPoints->SetPoint(nPoint, dPoint);
    }
    pPoints->Modified();
    pPolyData->Modified();
}

void configureLineActor(vtkPolyData* pPolyData,
                        vtkPolyDataMapper* pMapper,
                        vtkActor* pActor,
                        double dRed,
                        double dGreen,
                        double dBlue,
                        float fLineWidth)
{
    if(pPolyData == nullptr || pMapper == nullptr || pActor == nullptr) {
        return;
    }
    pMapper->SetInputData(pPolyData);
    pMapper->ScalarVisibilityOff();
    pActor->SetMapper(pMapper);
    pActor->GetProperty()->SetColor(dRed, dGreen, dBlue);
    pActor->GetProperty()->SetLineWidth(fLineWidth);
    pActor->GetProperty()->SetOpacity(1.0);
    pActor->GetProperty()->LightingOff();
    pActor->PickableOff();
}

void configureBackgroundActor(vtkPolyData* pPolyData,
                              vtkPolyDataMapper* pMapper,
                              vtkActor* pActor)
{
    if(pPolyData == nullptr || pMapper == nullptr || pActor == nullptr) {
        return;
    }
    pMapper->SetInputData(pPolyData);
    pMapper->ScalarVisibilityOff();
    pActor->SetMapper(pMapper);
    pActor->GetProperty()->SetColor(
                171.0 / 255.0, 232.0 / 255.0, 241.0 / 255.0);
    pActor->GetProperty()->SetOpacity(1.0);
    pActor->GetProperty()->SetRepresentationToSurface();
    pActor->GetProperty()->EdgeVisibilityOff();
    pActor->GetProperty()->LightingOff();
    // 底板两面都需要可见，相机翻到 XY 平面另一侧时仍由深度关系遮挡。
    pActor->GetProperty()->FrontfaceCullingOff();
    pActor->GetProperty()->BackfaceCullingOff();
    pActor->PickableOff();
}

bool calculateNiceTicks(double dMinimum,
                        double dMaximum,
                        std::vector<double>& vTicks,
                        double& dStep)
{
    vTicks.clear();
    dStep = 0.0;
    const double dRange = dMaximum - dMinimum;
    if(!vtkMath::IsFinite(dRange) || dRange <= 0.0) {
        return false;
    }

    const double dRawStep =
            dRange / static_cast<double>(PLANAR_TARGET_INTERVAL_COUNT);
    const double dMagnitude = std::pow(
                10.0, std::floor(std::log10(dRawStep)));
    if(!vtkMath::IsFinite(dMagnitude) || dMagnitude <= 0.0) {
        return false;
    }

    const double dNormalizedStep = dRawStep / dMagnitude;
    double dNiceFactor = 10.0;
    if(dNormalizedStep <= 1.0) {
        dNiceFactor = 1.0;
    } else if(dNormalizedStep <= 2.0) {
        dNiceFactor = 2.0;
    } else if(dNormalizedStep <= 2.5) {
        dNiceFactor = 2.5;
    } else if(dNormalizedStep <= 5.0) {
        dNiceFactor = 5.0;
    }
    dStep = dNiceFactor * dMagnitude;
    if(!vtkMath::IsFinite(dStep) || dStep <= 0.0) {
        return false;
    }

    const double dTolerance = dStep * 0.00000001;
    const double dFirstTick =
            std::ceil((dMinimum - dTolerance) / dStep) * dStep;
    for(int nIndex = 0; nIndex < 128; ++nIndex) {
        double dValue = dFirstTick + static_cast<double>(nIndex) * dStep;
        if(dValue > dMaximum + dTolerance) {
            break;
        }
        if(dValue >= dMinimum - dTolerance) {
            if(std::fabs(dValue) < dTolerance) {
                dValue = 0.0;
            }
            vTicks.push_back(dValue);
        }
    }
    return !vTicks.empty();
}

QString formatTickValue(double dValue, double dStep)
{
    const double dAbsoluteStep = std::fabs(dStep);
    if(std::fabs(dValue) < dAbsoluteStep * 0.00000001) {
        dValue = 0.0;
    }

    if(std::fabs(dValue) >= 1000000000.0) {
        return QString::number(dValue, 'g', 8);
    }

    int nDecimalCount = 0;
    double dScaledStep = dAbsoluteStep;
    while(nDecimalCount < 8 &&
          std::fabs(dScaledStep - std::floor(dScaledStep + 0.5)) >
          0.00000001) {
        dScaledStep *= 10.0;
        ++nDecimalCount;
    }
    return QString::number(dValue, 'f', nDecimalCount);
}

int roundedPixelOffset(double dValue)
{
    return static_cast<int>(dValue >= 0.0
                            ? std::floor(dValue + 0.5)
                            : std::ceil(dValue - 0.5));
}

}

class nmVTKPlanarScaleGridLayerPrivate;

/**
 * @brief 在 VTK 每次绘制组合 Prop 前更新相机相关轴边，不注册额外 Observer。
 */
class vtkNmPlanarScaleGridProp : public vtkPropAssembly
{
public:
    static vtkNmPlanarScaleGridProp* New();
    vtkTypeMacro(vtkNmPlanarScaleGridProp, vtkPropAssembly);

    void setOwner(nmVTKPlanarScaleGridLayerPrivate* pOwner)
    {
        m_pOwner = pOwner;
    }

    virtual int RenderOpaqueGeometry(vtkViewport* pViewport);
    virtual int RenderOverlay(vtkViewport* pViewport);

protected:
    vtkNmPlanarScaleGridProp()
        : m_pOwner(nullptr)
    {
    }

    virtual ~vtkNmPlanarScaleGridProp()
    {
        m_pOwner = nullptr;
    }

private:
    vtkNmPlanarScaleGridProp(const vtkNmPlanarScaleGridProp&);
    void operator=(const vtkNmPlanarScaleGridProp&);

    nmVTKPlanarScaleGridLayerPrivate* m_pOwner; ///< 非所有权指针。
};

vtkStandardNewMacro(vtkNmPlanarScaleGridProp);

class nmVTKPlanarScaleGridLayerPrivate
{
public:
    nmVTKPlanarScaleGridLayerPrivate()
        : m_pRootProp(vtkSmartPointer<vtkNmPlanarScaleGridProp>::New()),
          m_pBackgroundData(vtkSmartPointer<vtkPolyData>::New()),
          m_pGridData(vtkSmartPointer<vtkPolyData>::New()),
          m_pFrameData(vtkSmartPointer<vtkPolyData>::New()),
          m_pXAxisData(vtkSmartPointer<vtkPolyData>::New()),
          m_pYAxisData(vtkSmartPointer<vtkPolyData>::New()),
          m_pBackgroundMapper(vtkSmartPointer<vtkPolyDataMapper>::New()),
          m_pGridMapper(vtkSmartPointer<vtkPolyDataMapper>::New()),
          m_pFrameMapper(vtkSmartPointer<vtkPolyDataMapper>::New()),
          m_pXAxisMapper(vtkSmartPointer<vtkPolyDataMapper>::New()),
          m_pYAxisMapper(vtkSmartPointer<vtkPolyDataMapper>::New()),
          m_pBackgroundActor(vtkSmartPointer<vtkActor>::New()),
          m_pGridActor(vtkSmartPointer<vtkActor>::New()),
          m_pFrameActor(vtkSmartPointer<vtkActor>::New()),
          m_pXAxisActor(vtkSmartPointer<vtkActor>::New()),
          m_pYAxisActor(vtkSmartPointer<vtkActor>::New()),
          m_pLabelTextProperty(vtkSmartPointer<vtkTextProperty>::New()),
          m_dPlaneZ(0.0),
          m_dScale(0.0),
          m_dBackgroundZ(0.0),
          m_dGridZ(0.0),
          m_dAxisZ(0.0),
          m_dTickLength(0.0),
          m_dXTickStep(0.0),
          m_dYTickStep(0.0),
          m_bHasBounds(false),
          m_bAxesInitialized(false),
          m_bXAxisAtMaximum(false),
          m_bYAxisAtMaximum(false),
          m_nCameraSide(1)
    {
        for(int nIndex = 0; nIndex < 4; ++nIndex) {
            m_dBounds[nIndex] = 0.0;
        }

        configureBackgroundActor(m_pBackgroundData,
                                 m_pBackgroundMapper,
                                 m_pBackgroundActor);
        configureLineActor(m_pGridData, m_pGridMapper, m_pGridActor,
                           25.0 / 255.0, 25.0 / 255.0,
                           112.0 / 255.0, 1.0f);
        // 先使用 VTK 7.1 原生线型；不支持线型的后端会自然回退为实线。
        m_pGridActor->GetProperty()->SetLineStipplePattern(0xF0F0);
        m_pGridActor->GetProperty()->SetLineStippleRepeatFactor(1);
        configureLineActor(m_pFrameData, m_pFrameMapper, m_pFrameActor,
                           25.0 / 255.0, 25.0 / 255.0,
                           112.0 / 255.0, 1.5f);
        m_pFrameActor->GetProperty()->SetLineStipplePattern(0xFFFF);
        m_pFrameActor->GetProperty()->SetLineStippleRepeatFactor(1);
        configureLineActor(m_pXAxisData, m_pXAxisMapper, m_pXAxisActor,
                           1.0, 0.0, 0.0, 1.5f);
        configureLineActor(m_pYAxisData, m_pYAxisMapper, m_pYAxisActor,
                           0.0, 160.0 / 255.0, 0.0, 1.5f);

        m_pLabelTextProperty->SetFontFamilyToArial();
        m_pLabelTextProperty->SetFontSize(14);
        m_pLabelTextProperty->SetColor(
                    235.0 / 255.0, 235.0 / 255.0, 190.0 / 255.0);
        m_pLabelTextProperty->SetBold(0);
        m_pLabelTextProperty->SetItalic(0);
        // VTK 7.1 根据浅色文字自动计算黑色对比阴影，没有 SetShadowColor 接口。
        m_pLabelTextProperty->SetShadow(1);
        m_pLabelTextProperty->SetShadowOffset(1, -1);
        m_pLabelTextProperty->SetBackgroundOpacity(0.0);
        m_pLabelTextProperty->SetJustificationToCentered();
        m_pLabelTextProperty->SetVerticalJustificationToCentered();

        // RootProp 是 Scene 唯一接管的主 Prop，其余 Actor 生命周期均归本图层。
        m_pRootProp->setOwner(this);
        m_pRootProp->AddPart(m_pBackgroundActor);
        m_pRootProp->AddPart(m_pGridActor);
        m_pRootProp->AddPart(m_pFrameActor);
        m_pRootProp->AddPart(m_pXAxisActor);
        m_pRootProp->AddPart(m_pYAxisActor);
        m_pRootProp->PickableOff();
    }

    ~nmVTKPlanarScaleGridLayerPrivate()
    {
        // 先断开逐帧回调目标，再从组合 Prop 移除其持有的所有子 Prop 引用。
        m_pRootProp->setOwner(nullptr);
        clearLabels();
        m_pRootProp->RemovePart(m_pBackgroundActor);
        m_pRootProp->RemovePart(m_pGridActor);
        m_pRootProp->RemovePart(m_pFrameActor);
        m_pRootProp->RemovePart(m_pXAxisActor);
        m_pRootProp->RemovePart(m_pYAxisActor);
    }

    vtkProp* getRootProp() const
    {
        return m_pRootProp;
    }

    bool setBounds(double dXMinimum,
                   double dXMaximum,
                   double dYMinimum,
                   double dYMaximum,
                   double dPlaneZ)
    {
        std::vector<double> vXTicks;
        std::vector<double> vYTicks;
        double dXTickStep = 0.0;
        double dYTickStep = 0.0;
        if(!isValidPlanarBounds(dXMinimum, dXMaximum,
                                dYMinimum, dYMaximum, dPlaneZ) ||
           !calculateNiceTicks(dXMinimum, dXMaximum,
                               vXTicks, dXTickStep) ||
           !calculateNiceTicks(dYMinimum, dYMaximum,
                               vYTicks, dYTickStep)) {
            return false;
        }

        m_dBounds[0] = dXMinimum;
        m_dBounds[1] = dXMaximum;
        m_dBounds[2] = dYMinimum;
        m_dBounds[3] = dYMaximum;
        m_vXTicks = vXTicks;
        m_vYTicks = vYTicks;
        m_dXTickStep = dXTickStep;
        m_dYTickStep = dYTickStep;
        m_dPlaneZ = dPlaneZ;

        m_dScale = dXMaximum - dXMinimum;
        if(dYMaximum - dYMinimum > m_dScale) {
            m_dScale = dYMaximum - dYMinimum;
        }
        m_dTickLength = m_dScale * PLANAR_TICK_LENGTH_FACTOR;
        updateDepthCoordinates();

        rebuildBackgroundGeometry();
        rebuildGridGeometry();
        rebuildLabels();
        rebuildAxisGeometry(false, false);
        m_bHasBounds = true;
        return true;
    }

    bool getBounds(double dBounds[4]) const
    {
        if(dBounds == nullptr || !m_bHasBounds) {
            return false;
        }
        for(int nIndex = 0; nIndex < 4; ++nIndex) {
            dBounds[nIndex] = m_dBounds[nIndex];
        }
        return true;
    }

    void updateForRenderer(vtkRenderer* pRenderer)
    {
        if(pRenderer == nullptr || !m_bHasBounds) {
            return;
        }

        // 仅当相机明确越过带容差的平面分界时翻转深度顺序，侧视附近沿用上次侧别。
        const bool bDepthChanged = updateCameraSide(pRenderer);
        if(bDepthChanged) {
            updateGeometryDepth();
        }

        double dCornerDisplay[4][3];
        const double dCorners[4][3] = {
            { m_dBounds[0], m_dBounds[2], m_dPlaneZ },
            { m_dBounds[1], m_dBounds[2], m_dPlaneZ },
            { m_dBounds[1], m_dBounds[3], m_dPlaneZ },
            { m_dBounds[0], m_dBounds[3], m_dPlaneZ }
        };
        for(int nCorner = 0; nCorner < 4; ++nCorner) {
            if(!projectPoint(pRenderer, dCorners[nCorner],
                             dCornerDisplay[nCorner])) {
                return;
            }
        }

        const double dMinimumYAverage =
                (dCornerDisplay[0][1] + dCornerDisplay[1][1]) * 0.5;
        const double dMaximumYAverage =
                (dCornerDisplay[2][1] + dCornerDisplay[3][1]) * 0.5;
        const double dMinimumXAverage =
                (dCornerDisplay[0][0] + dCornerDisplay[3][0]) * 0.5;
        const double dMaximumXAverage =
                (dCornerDisplay[1][0] + dCornerDisplay[2][0]) * 0.5;

        // VTK 显示坐标原点位于左下角，平均值较小的边即当前底边或左边。
        const bool bXAxisAtMaximum = selectMaximumEdge(
                    dMinimumYAverage, dMaximumYAverage,
                    m_bXAxisAtMaximum);
        const bool bYAxisAtMaximum = selectMaximumEdge(
                    dMinimumXAverage, dMaximumXAverage,
                    m_bYAxisAtMaximum);
        if(!m_bAxesInitialized ||
           bXAxisAtMaximum != m_bXAxisAtMaximum ||
           bYAxisAtMaximum != m_bYAxisAtMaximum) {
            rebuildAxisGeometry(bXAxisAtMaximum, bYAxisAtMaximum);
        }
        updateLabelPositions(pRenderer,
                             bXAxisAtMaximum,
                             bYAxisAtMaximum);
    }

private:
    void updateDepthCoordinates()
    {
        const double dCameraSide = static_cast<double>(m_nCameraSide);
        m_dAxisZ = m_dPlaneZ + dCameraSide *
                m_dScale * PLANAR_AXIS_DEPTH_FACTOR;
        m_dGridZ = m_dPlaneZ - dCameraSide *
                m_dScale * PLANAR_GRID_DEPTH_FACTOR;
        m_dBackgroundZ = m_dPlaneZ - dCameraSide *
                m_dScale * PLANAR_BACKGROUND_DEPTH_FACTOR;
    }

    bool updateCameraSide(vtkRenderer* pRenderer)
    {
        vtkCamera* pCamera = pRenderer != nullptr
                ? pRenderer->GetActiveCamera() : nullptr;
        const double* pCameraPosition = pCamera != nullptr
                ? pCamera->GetPosition() : nullptr;
        if(pCameraPosition == nullptr ||
           !vtkMath::IsFinite(pCameraPosition[2])) {
            return false;
        }

        const double dDistanceToPlane = pCameraPosition[2] - m_dPlaneZ;
        const double dTolerance =
                m_dScale * PLANAR_CAMERA_SIDE_TOLERANCE_FACTOR;
        int nCameraSide = m_nCameraSide;
        if(dDistanceToPlane > dTolerance) {
            nCameraSide = 1;
        } else if(dDistanceToPlane < -dTolerance) {
            nCameraSide = -1;
        }
        if(nCameraSide == m_nCameraSide) {
            return false;
        }

        m_nCameraSide = nCameraSide;
        updateDepthCoordinates();
        return true;
    }

    bool selectMaximumEdge(double dMinimumEdgeAverage,
                           double dMaximumEdgeAverage,
                           bool bCurrentMaximum) const
    {
        const double dDifference =
                dMaximumEdgeAverage - dMinimumEdgeAverage;
        if(dDifference < -PLANAR_EDGE_SWITCH_PIXEL_TOLERANCE) {
            return true;
        }
        if(dDifference > PLANAR_EDGE_SWITCH_PIXEL_TOLERANCE) {
            return false;
        }
        return m_bAxesInitialized ? bCurrentMaximum : false;
    }

    void updateGeometryDepth()
    {
        // 相机翻面只改已有点的 Z，不重建底板、比例线拓扑或任何 VTK Prop。
        updatePolyDataZ(m_pBackgroundData, m_dBackgroundZ);
        updatePolyDataZ(m_pGridData, m_dGridZ);
        updatePolyDataZ(m_pFrameData, m_dAxisZ);
        updatePolyDataZ(m_pXAxisData, m_dAxisZ);
        updatePolyDataZ(m_pYAxisData, m_dAxisZ);
    }

    void rebuildBackgroundGeometry()
    {
        vtkSmartPointer<vtkPoints> pPoints =
                vtkSmartPointer<vtkPoints>::New();
        vtkSmartPointer<vtkCellArray> pPolygons =
                vtkSmartPointer<vtkCellArray>::New();
        pPoints->SetDataTypeToDouble();

        vtkIdType nPointIds[4];
        nPointIds[0] = pPoints->InsertNextPoint(
                    m_dBounds[0], m_dBounds[2], m_dBackgroundZ);
        nPointIds[1] = pPoints->InsertNextPoint(
                    m_dBounds[1], m_dBounds[2], m_dBackgroundZ);
        nPointIds[2] = pPoints->InsertNextPoint(
                    m_dBounds[1], m_dBounds[3], m_dBackgroundZ);
        nPointIds[3] = pPoints->InsertNextPoint(
                    m_dBounds[0], m_dBounds[3], m_dBackgroundZ);
        pPolygons->InsertNextCell(4, nPointIds);
        applySurfaceData(m_pBackgroundData, pPoints, pPolygons);
    }

    void rebuildGridGeometry()
    {
        vtkSmartPointer<vtkPoints> pPoints =
                vtkSmartPointer<vtkPoints>::New();
        vtkSmartPointer<vtkCellArray> pLines =
                vtkSmartPointer<vtkCellArray>::New();
        pPoints->SetDataTypeToDouble();

        // 内部主刻度使用虚线；矩形外框由独立实线 Actor 绘制。
        const double dXTolerance = m_dXTickStep * 0.00000001;
        for(std::size_t nIndex = 0; nIndex < m_vXTicks.size(); ++nIndex) {
            const double dX = m_vXTicks[nIndex];
            if(dX > m_dBounds[0] + dXTolerance &&
               dX < m_dBounds[1] - dXTolerance) {
                appendLine(pPoints, pLines, dX, m_dBounds[2], m_dGridZ,
                           dX, m_dBounds[3], m_dGridZ);
            }
        }
        const double dYTolerance = m_dYTickStep * 0.00000001;
        for(std::size_t nIndex = 0; nIndex < m_vYTicks.size(); ++nIndex) {
            const double dY = m_vYTicks[nIndex];
            if(dY > m_dBounds[2] + dYTolerance &&
               dY < m_dBounds[3] - dYTolerance) {
                appendLine(pPoints, pLines, m_dBounds[0], dY, m_dGridZ,
                           m_dBounds[1], dY, m_dGridZ);
            }
        }
        applyLineData(m_pGridData, pPoints, pLines);
    }

    void rebuildAxisGeometry(bool bXAxisAtMaximum,
                             bool bYAxisAtMaximum)
    {
        const double dXAxisY = bXAxisAtMaximum
                ? m_dBounds[3] : m_dBounds[2];
        const double dXAxisDirection = bXAxisAtMaximum ? 1.0 : -1.0;
        vtkSmartPointer<vtkPoints> pXPoints =
                vtkSmartPointer<vtkPoints>::New();
        vtkSmartPointer<vtkCellArray> pXLines =
                vtkSmartPointer<vtkCellArray>::New();
        pXPoints->SetDataTypeToDouble();
        appendLine(pXPoints, pXLines,
                   m_dBounds[0], dXAxisY, m_dAxisZ,
                   m_dBounds[1], dXAxisY, m_dAxisZ);
        for(std::size_t nIndex = 0; nIndex < m_vXTicks.size(); ++nIndex) {
            appendLine(pXPoints, pXLines,
                       m_vXTicks[nIndex], dXAxisY, m_dAxisZ,
                       m_vXTicks[nIndex],
                       dXAxisY + dXAxisDirection * m_dTickLength,
                       m_dAxisZ);
        }
        applyLineData(m_pXAxisData, pXPoints, pXLines);

        const double dYAxisX = bYAxisAtMaximum
                ? m_dBounds[1] : m_dBounds[0];
        const double dYAxisDirection = bYAxisAtMaximum ? 1.0 : -1.0;
        vtkSmartPointer<vtkPoints> pYPoints =
                vtkSmartPointer<vtkPoints>::New();
        vtkSmartPointer<vtkCellArray> pYLines =
                vtkSmartPointer<vtkCellArray>::New();
        pYPoints->SetDataTypeToDouble();
        appendLine(pYPoints, pYLines,
                   dYAxisX, m_dBounds[2], m_dAxisZ,
                   dYAxisX, m_dBounds[3], m_dAxisZ);
        for(std::size_t nIndex = 0; nIndex < m_vYTicks.size(); ++nIndex) {
            appendLine(pYPoints, pYLines,
                       dYAxisX, m_vYTicks[nIndex], m_dAxisZ,
                       dYAxisX + dYAxisDirection * m_dTickLength,
                       m_vYTicks[nIndex], m_dAxisZ);
        }
        applyLineData(m_pYAxisData, pYPoints, pYLines);

        // 外框只绘制当前坐标轴的两条对边，底边和左边分别由红、绿轴覆盖。
        vtkSmartPointer<vtkPoints> pFramePoints =
                vtkSmartPointer<vtkPoints>::New();
        vtkSmartPointer<vtkCellArray> pFrameLines =
                vtkSmartPointer<vtkCellArray>::New();
        pFramePoints->SetDataTypeToDouble();
        const double dOppositeXAxisY = bXAxisAtMaximum
                ? m_dBounds[2] : m_dBounds[3];
        const double dOppositeYAxisX = bYAxisAtMaximum
                ? m_dBounds[0] : m_dBounds[1];
        appendLine(pFramePoints, pFrameLines,
                   m_dBounds[0], dOppositeXAxisY, m_dAxisZ,
                   m_dBounds[1], dOppositeXAxisY, m_dAxisZ);
        appendLine(pFramePoints, pFrameLines,
                   dOppositeYAxisX, m_dBounds[2], m_dAxisZ,
                   dOppositeYAxisX, m_dBounds[3], m_dAxisZ);
        applyLineData(m_pFrameData, pFramePoints, pFrameLines);

        m_bXAxisAtMaximum = bXAxisAtMaximum;
        m_bYAxisAtMaximum = bYAxisAtMaximum;
        m_bAxesInitialized = true;
    }

    vtkSmartPointer<vtkTextActor> createLabel(
            const QString& sText)
    {
        vtkSmartPointer<vtkTextActor> pLabel =
                vtkSmartPointer<vtkTextActor>::New();
        const QByteArray aText = sText.toUtf8();
        pLabel->SetInput(aText.constData());
        pLabel->SetTextProperty(m_pLabelTextProperty);
        pLabel->SetTextScaleModeToNone();
        pLabel->GetProperty()->SetDisplayLocationToForeground();
        pLabel->PickableOff();
        m_pRootProp->AddPart(pLabel);
        return pLabel;
    }

    void rebuildLabels()
    {
        clearLabels();
        for(std::size_t nIndex = 0; nIndex < m_vXTicks.size(); ++nIndex) {
            m_vXLabels.push_back(createLabel(
                                    formatTickValue(m_vXTicks[nIndex],
                                                    m_dXTickStep)));
        }
        for(std::size_t nIndex = 0; nIndex < m_vYTicks.size(); ++nIndex) {
            m_vYLabels.push_back(createLabel(
                                    formatTickValue(m_vYTicks[nIndex],
                                                    m_dYTickStep)));
        }
    }

    void clearLabels()
    {
        for(std::size_t nIndex = 0; nIndex < m_vXLabels.size(); ++nIndex) {
            m_pRootProp->RemovePart(m_vXLabels[nIndex]);
        }
        for(std::size_t nIndex = 0; nIndex < m_vYLabels.size(); ++nIndex) {
            m_pRootProp->RemovePart(m_vYLabels[nIndex]);
        }
        m_vXLabels.clear();
        m_vYLabels.clear();
    }

    bool projectPoint(vtkRenderer* pRenderer,
                      const double dWorld[3],
                      double dDisplay[3]) const
    {
        if(pRenderer == nullptr || dWorld == nullptr || dDisplay == nullptr) {
            return false;
        }
        pRenderer->SetWorldPoint(
                    dWorld[0], dWorld[1], dWorld[2], 1.0);
        pRenderer->WorldToDisplay();
        const double* pDisplay = pRenderer->GetDisplayPoint();
        if(pDisplay == nullptr ||
           !vtkMath::IsFinite(pDisplay[0]) ||
           !vtkMath::IsFinite(pDisplay[1]) ||
           !vtkMath::IsFinite(pDisplay[2])) {
            return false;
        }
        dDisplay[0] = pDisplay[0];
        dDisplay[1] = pDisplay[1];
        dDisplay[2] = pDisplay[2];
        return true;
    }

    bool calculateDisplayDirection(vtkRenderer* pRenderer,
                                   const double dAnchor[3],
                                   const double dOuterPoint[3],
                                   double dDirection[2]) const
    {
        double dAnchorDisplay[3];
        double dOuterDisplay[3];
        if(!projectPoint(pRenderer, dAnchor, dAnchorDisplay) ||
           !projectPoint(pRenderer, dOuterPoint, dOuterDisplay)) {
            return false;
        }
        const double dX = dOuterDisplay[0] - dAnchorDisplay[0];
        const double dY = dOuterDisplay[1] - dAnchorDisplay[1];
        const double dLength = std::sqrt(dX * dX + dY * dY);
        if(!vtkMath::IsFinite(dLength) || dLength < 0.000001) {
            return false;
        }
        dDirection[0] = dX / dLength;
        dDirection[1] = dY / dLength;
        return true;
    }

    void updateLabelPositions(vtkRenderer* pRenderer,
                              bool bXAxisAtMaximum,
                              bool bYAxisAtMaximum)
    {
        const double dXAxisY = bXAxisAtMaximum
                ? m_dBounds[3] : m_dBounds[2];
        const double dXAxisDirection = bXAxisAtMaximum ? 1.0 : -1.0;
        const double dXAxisAnchor[3] = {
            (m_dBounds[0] + m_dBounds[1]) * 0.5,
            dXAxisY,
            m_dAxisZ
        };
        const double dXAxisOuterPoint[3] = {
            dXAxisAnchor[0],
            dXAxisY + dXAxisDirection * m_dTickLength,
            m_dAxisZ
        };
        double dXAxisDisplayDirection[2] = { 0.0, -1.0 };
        calculateDisplayDirection(pRenderer,
                                  dXAxisAnchor,
                                  dXAxisOuterPoint,
                                  dXAxisDisplayDirection);
        const int nXAxisOffsetX = roundedPixelOffset(
                    dXAxisDisplayDirection[0] * PLANAR_LABEL_PIXEL_GAP);
        const int nXAxisOffsetY = roundedPixelOffset(
                    dXAxisDisplayDirection[1] * PLANAR_LABEL_PIXEL_GAP);

        const double dXAxisMinimumPoint[3] = {
            m_dBounds[0], dXAxisY, m_dAxisZ
        };
        const double dXAxisMaximumPoint[3] = {
            m_dBounds[1], dXAxisY, m_dAxisZ
        };
        double dXAxisPositiveDirection[2] = { 1.0, 0.0 };
        calculateDisplayDirection(pRenderer,
                                  dXAxisMinimumPoint,
                                  dXAxisMaximumPoint,
                                  dXAxisPositiveDirection);
        const double dXAxisCornerValue = bYAxisAtMaximum
                ? m_dBounds[1] : m_dBounds[0];
        const double dXAxisCornerDirection = bYAxisAtMaximum ? -1.0 : 1.0;
        const double dXAxisTolerance = m_dXTickStep * 0.00000001;
        for(std::size_t nIndex = 0; nIndex < m_vXLabels.size(); ++nIndex) {
            const double dLabelWorld[3] = {
                m_vXTicks[nIndex], dXAxisOuterPoint[1], m_dAxisZ
            };
            double dLabelDisplay[3];
            if(!projectPoint(pRenderer, dLabelWorld, dLabelDisplay)) {
                m_vXLabels[nIndex]->SetVisibility(0);
                continue;
            }
            int nOffsetX = nXAxisOffsetX;
            int nOffsetY = nXAxisOffsetY;
            if(std::fabs(m_vXTicks[nIndex] - dXAxisCornerValue) <=
               dXAxisTolerance) {
                nOffsetX += roundedPixelOffset(
                            dXAxisPositiveDirection[0] *
                            dXAxisCornerDirection *
                            PLANAR_CORNER_LABEL_PIXEL_SHIFT);
                nOffsetY += roundedPixelOffset(
                            dXAxisPositiveDirection[1] *
                            dXAxisCornerDirection *
                            PLANAR_CORNER_LABEL_PIXEL_SHIFT);
            }
            m_vXLabels[nIndex]->SetDisplayPosition(
                        roundedPixelOffset(dLabelDisplay[0]) + nOffsetX,
                        roundedPixelOffset(dLabelDisplay[1]) + nOffsetY);
            m_vXLabels[nIndex]->SetVisibility(1);
        }

        const double dYAxisX = bYAxisAtMaximum
                ? m_dBounds[1] : m_dBounds[0];
        const double dYAxisDirection = bYAxisAtMaximum ? 1.0 : -1.0;
        const double dYAxisAnchor[3] = {
            dYAxisX,
            (m_dBounds[2] + m_dBounds[3]) * 0.5,
            m_dAxisZ
        };
        const double dYAxisOuterPoint[3] = {
            dYAxisX + dYAxisDirection * m_dTickLength,
            dYAxisAnchor[1],
            m_dAxisZ
        };
        double dYAxisDisplayDirection[2] = { -1.0, 0.0 };
        calculateDisplayDirection(pRenderer,
                                  dYAxisAnchor,
                                  dYAxisOuterPoint,
                                  dYAxisDisplayDirection);
        const int nYAxisOffsetX = roundedPixelOffset(
                    dYAxisDisplayDirection[0] * PLANAR_LABEL_PIXEL_GAP);
        const int nYAxisOffsetY = roundedPixelOffset(
                    dYAxisDisplayDirection[1] * PLANAR_LABEL_PIXEL_GAP);

        const double dYAxisMinimumPoint[3] = {
            dYAxisX, m_dBounds[2], m_dAxisZ
        };
        const double dYAxisMaximumPoint[3] = {
            dYAxisX, m_dBounds[3], m_dAxisZ
        };
        double dYAxisPositiveDirection[2] = { 0.0, 1.0 };
        calculateDisplayDirection(pRenderer,
                                  dYAxisMinimumPoint,
                                  dYAxisMaximumPoint,
                                  dYAxisPositiveDirection);
        const double dYAxisCornerValue = bXAxisAtMaximum
                ? m_dBounds[3] : m_dBounds[2];
        const double dYAxisCornerDirection = bXAxisAtMaximum ? -1.0 : 1.0;
        const double dYAxisTolerance = m_dYTickStep * 0.00000001;
        for(std::size_t nIndex = 0; nIndex < m_vYLabels.size(); ++nIndex) {
            const double dLabelWorld[3] = {
                dYAxisOuterPoint[0], m_vYTicks[nIndex], m_dAxisZ
            };
            double dLabelDisplay[3];
            if(!projectPoint(pRenderer, dLabelWorld, dLabelDisplay)) {
                m_vYLabels[nIndex]->SetVisibility(0);
                continue;
            }
            int nOffsetX = nYAxisOffsetX;
            int nOffsetY = nYAxisOffsetY;
            if(std::fabs(m_vYTicks[nIndex] - dYAxisCornerValue) <=
               dYAxisTolerance) {
                nOffsetX += roundedPixelOffset(
                            dYAxisPositiveDirection[0] *
                            dYAxisCornerDirection *
                            PLANAR_CORNER_LABEL_PIXEL_SHIFT);
                nOffsetY += roundedPixelOffset(
                            dYAxisPositiveDirection[1] *
                            dYAxisCornerDirection *
                            PLANAR_CORNER_LABEL_PIXEL_SHIFT);
            }
            m_vYLabels[nIndex]->SetDisplayPosition(
                        roundedPixelOffset(dLabelDisplay[0]) + nOffsetX,
                        roundedPixelOffset(dLabelDisplay[1]) + nOffsetY);
            m_vYLabels[nIndex]->SetVisibility(1);
        }
    }

    vtkSmartPointer<vtkNmPlanarScaleGridProp> m_pRootProp;
    vtkSmartPointer<vtkPolyData> m_pBackgroundData;
    vtkSmartPointer<vtkPolyData> m_pGridData;
    vtkSmartPointer<vtkPolyData> m_pFrameData;
    vtkSmartPointer<vtkPolyData> m_pXAxisData;
    vtkSmartPointer<vtkPolyData> m_pYAxisData;
    vtkSmartPointer<vtkPolyDataMapper> m_pBackgroundMapper;
    vtkSmartPointer<vtkPolyDataMapper> m_pGridMapper;
    vtkSmartPointer<vtkPolyDataMapper> m_pFrameMapper;
    vtkSmartPointer<vtkPolyDataMapper> m_pXAxisMapper;
    vtkSmartPointer<vtkPolyDataMapper> m_pYAxisMapper;
    vtkSmartPointer<vtkActor> m_pBackgroundActor;
    vtkSmartPointer<vtkActor> m_pGridActor;
    vtkSmartPointer<vtkActor> m_pFrameActor;
    vtkSmartPointer<vtkActor> m_pXAxisActor;
    vtkSmartPointer<vtkActor> m_pYAxisActor;
    vtkSmartPointer<vtkTextProperty> m_pLabelTextProperty;
    std::vector<vtkSmartPointer<vtkTextActor> > m_vXLabels;
    std::vector<vtkSmartPointer<vtkTextActor> > m_vYLabels;
    std::vector<double> m_vXTicks;
    std::vector<double> m_vYTicks;
    double m_dBounds[4];
    double m_dPlaneZ;
    double m_dScale;
    double m_dBackgroundZ;
    double m_dGridZ;
    double m_dAxisZ;
    double m_dTickLength;
    double m_dXTickStep;
    double m_dYTickStep;
    bool m_bHasBounds;
    bool m_bAxesInitialized;
    bool m_bXAxisAtMaximum;
    bool m_bYAxisAtMaximum;
    int m_nCameraSide;
};

int vtkNmPlanarScaleGridProp::RenderOpaqueGeometry(vtkViewport* pViewport)
{
    if(m_pOwner != nullptr) {
        m_pOwner->updateForRenderer(vtkRenderer::SafeDownCast(pViewport));
    }
    return this->Superclass::RenderOpaqueGeometry(pViewport);
}

int vtkNmPlanarScaleGridProp::RenderOverlay(vtkViewport* pViewport)
{
    if(m_pOwner != nullptr) {
        // Overlay 阶段再次同步屏幕坐标，确保文字使用本帧最终相机矩阵。
        m_pOwner->updateForRenderer(vtkRenderer::SafeDownCast(pViewport));
    }
    return this->Superclass::RenderOverlay(pViewport);
}

nmVTKPlanarScaleGridLayer::nmVTKPlanarScaleGridLayer(
        const QString& sLayerId)
    : nmVTKRenderLayer(sLayerId),
      m_pPrivate(new nmVTKPlanarScaleGridLayerPrivate)
{
    Q_ASSERT(isPlanarScaleGridGuiThread());
    setRenderProp(m_pPrivate->getRootProp());
}

nmVTKPlanarScaleGridLayer::~nmVTKPlanarScaleGridLayer()
{
    Q_ASSERT(isPlanarScaleGridGuiThread());
    // 先从 Renderer 移除组合 Prop，再清除其逐帧更新目标和子 Prop 引用。
    detach();
    delete m_pPrivate;
    m_pPrivate = nullptr;
}

bool nmVTKPlanarScaleGridLayer::setBounds(
        double dXMinimum,
        double dXMaximum,
        double dYMinimum,
        double dYMaximum,
        double dPlaneZ)
{
    Q_ASSERT(isPlanarScaleGridGuiThread());
    return isPlanarScaleGridGuiThread() && m_pPrivate != nullptr &&
            m_pPrivate->setBounds(dXMinimum, dXMaximum,
                                  dYMinimum, dYMaximum, dPlaneZ);
}

bool nmVTKPlanarScaleGridLayer::getBounds(double dBounds[4]) const
{
    return m_pPrivate != nullptr && m_pPrivate->getBounds(dBounds);
}