vc实现NURBS曲线鼠标交互的代码

以下是一个基于MFC的NURBS曲线鼠标交互的代码示例：

首先，需要定义一个CNurbsCurve类，用于存储NURBS曲线的控制点、权值等信息，并提供计算曲线点的方法。

class CNurbsCurve
{
public:
    CNurbsCurve();
    virtual ~CNurbsCurve();

    void AddControlPoint(const CPoint& point);
    void SetDegree(int degree);
    void SetKnotVector(const std::vector<double>& knotVector);
    void SetWeights(const std::vector<double>& weights);

    int GetDegree() const;
    int GetControlPointsCount() const;
    const CPoint& GetControlPoint(int index) const;
    const std::vector<double>& GetKnotVector() const;
    const std::vector<double>& GetWeights() const;

    void CalculateCurvePoints(std::vector<CPoint>& curvePoints, int segments) const;

private:
    int m_nDegree;
    std::vector<CPoint> m_controlPoints;
    std::vector<double> m_knotVector;
    std::vector<double> m_weights;
};

接下来，在对应的MFC窗口类中添加以下代码：

class CMyWnd : public CWnd
{
public:
    CMyWnd();
    virtual ~CMyWnd();

protected:
    afx_msg void OnMouseMove(UINT nFlags, CPoint point);
    afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
    afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
    afx_msg void OnPaint();
    DECLARE_MESSAGE_MAP()

private:
    CNurbsCurve m_nurbsCurve;
    bool m_isDragging;
    int m_draggingIndex;
};

BEGIN_MESSAGE_MAP(CMyWnd, CWnd)
    ON_WM_MOUSEMOVE()
    ON_WM_LBUTTONDOWN()
    ON_WM_LBUTTONUP()
    ON_WM_PAINT()
END_MESSAGE_MAP()

CMyWnd::CMyWnd() : m_isDragging(false), m_draggingIndex(-1)
{
    // 初始化NURBS曲线
    m_nurbsCurve.SetDegree(3);
    m_nurbsCurve.AddControlPoint(CPoint(50, 50));
    m_nurbsCurve.AddControlPoint(CPoint(150, 150));
    m_nurbsCurve.AddControlPoint(CPoint(250, 100));
    m_nurbsCurve.AddControlPoint(CPoint(350, 200));
    m_nurbsCurve.AddControlPoint(CPoint(450, 150));
    m_nurbsCurve.SetKnotVector({0, 0, 0, 0.25, 0.5, 0.75, 1, 1, 1});
    m_nurbsCurve.SetWeights({1, 1, 1, 1, 1});

    // 创建窗口
    Create(NULL, NULL, WS_OVERLAPPEDWINDOW, CRect(0, 0, 500, 500));
}

CMyWnd::~CMyWnd()
{
}

void CMyWnd::OnMouseMove(UINT nFlags, CPoint point)
{
    if (m_isDragging) {
        m_nurbsCurve.GetControlPoint(m_draggingIndex) = point;
        Invalidate();
    }
}

void CMyWnd::OnLButtonDown(UINT nFlags, CPoint point)
{
    for (int i = 0; i < m_nurbsCurve.GetControlPointsCount(); i++) {
        if (abs(point.x - m_nurbsCurve.GetControlPoint(i).x) < 5 &&
            abs(point.y - m_nurbsCurve.GetControlPoint(i).y) < 5) {
            m_isDragging = true;
            m_draggingIndex = i;
            break;
        }
    }
}

void CMyWnd::OnLButtonUp(UINT nFlags, CPoint point)
{
    m_isDragging = false;
    m_draggingIndex = -1;
}

void CMyWnd::OnPaint()
{
    CPaintDC dc(this);

    // 计算曲线上的点
    std::vector<CPoint> curvePoints;
    m_nurbsCurve.CalculateCurvePoints(curvePoints, 50);

    // 绘制控制点
    for (int i = 0; i < m_nurbsCurve.GetControlPointsCount(); i++) {
        dc.Ellipse(m_nurbsCurve.GetControlPoint(i).x - 5,
                   m_nurbsCurve.GetControlPoint(i).y - 5,
                   m_nurbsCurve.GetControlPoint(i).x + 5,
                   m_nurbsCurve.GetControlPoint(i).y + 5);
    }

    // 绘制曲线
    if (curvePoints.size() > 0) {
        CPoint prevPoint = curvePoints[0];
        for (int i = 1; i < curvePoints.size(); i++) {
            dc.MoveTo(prevPoint);
            dc.LineTo(curvePoints[i]);
            prevPoint = curvePoints[i];
        }
    }
}

以上代码实现了NURBS曲线的鼠标交互，可以通过拖动控制点来改变曲线形状。具体实现细节可以根据需要进行修改。