Q3DSurface仅绘制数据范围一半的问题排查求助

核心问题分析 #

渲染范围仅显示0到50的核心原因是每次调用generateWaterfallData时重复执行m_surfaceGraph->addSeries(m_sqrtSinSeries)，同一个系列被多次添加到图表中，干扰了Q3DSurface的渲染逻辑，最终导致仅显示部分数据。

此外还有两个次要问题：

• 每次生成数据时重复设置轴的标题、格式、旋转等属性，造成不必要的性能浪费
• timerEvent中传递的t值过大（QTime::currentTime().msecsSinceStartOfDay()返回当天毫秒数，最大可达~8.6e7），导致std::sin(k_x * x + omega * t)的参数超出有效计算范围，动画效果异常

修复步骤 #

1. 仅初始化一次系列与轴属性 #

将添加系列、设置轴标题/格式/旋转等初始化操作移到initialize函数中，避免重复执行：

bool Waterfall3dChart::initialize() {
    if (!m_surfaceGraph->hasContext())
        return false;

    m_surfaceWidget = new QWidget;
    auto* hLayout = new QHBoxLayout(m_surfaceWidget);
    m_container = QWidget::createWindowContainer(m_surfaceGraph, m_surfaceWidget);
    m_container->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    m_container->setFocusPolicy(Qt::StrongFocus);
    hLayout->addWidget(m_container, 1);

    auto* vLayout = new QVBoxLayout();
    hLayout->addLayout(vLayout);
    vLayout->setAlignment(Qt::AlignTop);

    m_surfaceGraph->scene()->activeCamera()->setZoomLevel(85.f);
    m_surfaceGraph->scene()->activeCamera()->setCameraPreset(Q3DCamera::CameraPresetIsometricRight);
    m_surfaceGraph->activeTheme()->setType(Q3DTheme::ThemeRetro);

    m_surfaceGraph->setAxisX(new QValue3DAxis);
    m_surfaceGraph->setAxisY(new QValue3DAxis);
    m_surfaceGraph->setAxisZ(new QValue3DAxis);

    // 初始化轴属性（仅执行一次）
    m_surfaceGraph->axisX()->setLabelFormat("%.2f");
    m_surfaceGraph->axisZ()->setLabelFormat("%.2f");
    m_surfaceGraph->axisX()->setRange(0, 100);
    m_surfaceGraph->axisY()->setRange(sampleMin, sampleMax);
    m_surfaceGraph->axisZ()->setRange(0, 100);
    m_surfaceGraph->axisX()->setLabelAutoRotation(30.f);
    m_surfaceGraph->axisY()->setLabelAutoRotation(90.f);
    m_surfaceGraph->axisZ()->setLabelAutoRotation(30.f);
    m_surfaceGraph->axisX()->setTitleVisible(true);
    m_surfaceGraph->axisY()->setTitleVisible(true);
    m_surfaceGraph->axisZ()->setTitleVisible(true);
    m_surfaceGraph->axisX()->setTitle("X");
    m_surfaceGraph->axisY()->setTitle("Y");
    m_surfaceGraph->axisZ()->setTitle("Z");

    m_sqrtSinProxy = new QSurfaceDataProxy();
    m_sqrtSinSeries = new QSurface3DSeries(m_sqrtSinProxy);
    setGradient();
    m_sqrtSinSeries->setDrawMode(QSurface3DSeries::DrawFlag::DrawSurfaceAndWireframe);
    m_sqrtSinSeries->setFlatShadingEnabled(true);
    
    // 仅添加一次系列
    m_surfaceGraph->addSeries(m_sqrtSinSeries);

    return true;
}

2. 简化generateWaterfallData函数 #

移除重复的初始化代码，只保留数据生成和必要的轴范围调整：

void Waterfall3dChart::generateWaterfallData(float t) {
    const int SIZE = 100;   // Define the size of the grid
    const double A = 0.7;   // Amplitude
    const double k_x = 0.1; // Wave number in x direction
    const double k_y = 0.1; // Wave number in y direction
    const double omega = 1; // Angular frequency (Increase it to increase animation speed)

    float z;
    auto* dataArray = new QSurfaceDataArray;
    dataArray->reserve(SIZE);
    for (int x = 0; x < SIZE; ++x) {
        auto* newRow = new QSurfaceDataRow;
        newRow->reserve(SIZE);
        for (int y = 0; y < SIZE; ++y) {
            // Combine sine and Gaussian functions
            z = A * std::sin(k_x * x + omega * t) + std::cos(k_y * y);
            newRow->append(QSurfaceDataItem({(float)x, z, (float)y}));
        }
        dataArray->append(newRow);
    }

    // 仅在SIZE动态变化时调整轴范围，否则可移除
    m_surfaceGraph->axisX()->setRange(0, SIZE);
    m_surfaceGraph->axisZ()->setRange(0, SIZE);

    m_sqrtSinProxy->resetArray(dataArray);
}

3. 修复时间参数t的溢出问题 #

添加成员变量记录累计时间，避免过大的参数值：
在Waterfall3DChart.h的private区域添加：

private:
    // ... 现有成员 ...
    float m_elapsedTime = 0.f;

修改timerEvent函数：

void Waterfall3dChart::timerEvent(QTimerEvent* event) {
    // 按定时器间隔累加时间，保证动画平滑
    m_elapsedTime += 0.1f;
    generateWaterfallData(m_elapsedTime);
}

验证修复 #

完成上述修改后，Q3DSurface会正确渲染0到100范围的完整曲面，动画效果也会恢复正常。

内容的提问来源于stack exchange，提问作者Soroush Shariaty