vc实现bezier曲面鼠标交互的代码

以下是基于MFC的Bezier曲面鼠标交互代码：

首先，需要定义Bezier曲面的控制点数组和曲面网格数组，以及当前鼠标所选中的控制点索引：

#define MAX_ORDER 20 // 最大阶数
CPoint m_ControlPts[MAX_ORDER][MAX_ORDER]; // 控制点数组
int m_nOrderU, m_nOrderV; // 控制点阶数
int m_nGridU, m_nGridV; // 曲面网格数
vector<CPoint> m_SurfaceGrids; // 曲面网格数组
int m_nSelectedCtrlPt = -1; // 当前选中的控制点索引

在初始化函数中，可以初始化控制点阶数、曲面网格数、以及控制点数组的初始值：

void CMyView::Init()
{
    // 初始化控制点阶数和曲面网格数
    m_nOrderU = 4;
    m_nOrderV = 4;
    m_nGridU = 30;
    m_nGridV = 30;

    // 初始化控制点数组
    int cxClient = GetClientRect().Width();
    int cyClient = GetClientRect().Height();
    int nMargin = 50;
    int nCtrlPtSize = 10;
    int nCtrlPtGap = (cxClient - nMargin * 2) / (m_nOrderU - 1);
    int nCtrlPtX = nMargin;
    int nCtrlPtY = nMargin;
    for (int i = 0; i < m_nOrderU; i++)
    {
        for (int j = 0; j < m_nOrderV; j++)
        {
            m_ControlPts[i][j] = CPoint(nCtrlPtX, nCtrlPtY);
            nCtrlPtY += nCtrlPtGap;
        }
        nCtrlPtX += nCtrlPtGap;
        nCtrlPtY = nMargin;
    }
}

在OnLButtonDown函数中，可以判断当前鼠标是否选中了某个控制点，并记录下当前选中的控制点索引：

void CMyView::OnLButtonDown(UINT nFlags, CPoint point)
{
    CPoint ptClient = point;
    ScreenToClient(&ptClient);

    // 判断当前鼠标是否选中了某个控制点
    for (int i = 0; i < m_nOrderU; i++)
    {
        for (int j = 0; j < m_nOrderV; j++)
        {
            CRect rcCtrlPt(m_ControlPts[i][j], CSize(10, 10));
            if (rcCtrlPt.PtInRect(ptClient))
            {
                m_nSelectedCtrlPt = i * m_nOrderV + j;
                return;
            }
        }
    }

    CView::OnLButtonDown(nFlags, point);
}

在OnMouseMove函数中，可以根据当前选中的控制点索引来更新该控制点的位置，并重新生成曲面网格数组：

void CMyView::OnMouseMove(UINT nFlags, CPoint point)
{
    if (m_nSelectedCtrlPt >= 0)
    {
        CPoint ptClient = point;
        ScreenToClient(&ptClient);

        // 更新当前选中的控制点位置
        int i = m_nSelectedCtrlPt / m_nOrderV;
        int j = m_nSelectedCtrlPt % m_nOrderV;
        m_ControlPts[i][j] = ptClient;

        // 重新生成曲面网格数组
        GenerateSurfaceGrids();
        Invalidate(FALSE);
    }

    CView::OnMouseMove(nFlags, point);
}

最后，实现GenerateSurfaceGrids函数来生成曲面网格数组，该函数使用De Casteljau算法计算Bezier曲面在每个网格上的坐标，并将结果保存在曲面网格数组中：

void CMyView::GenerateSurfaceGrids()
{
    m_SurfaceGrids.clear();

    // 计算Bezier曲面在每个网格上的坐标
    double uStep = 1.0 / m_nGridU;
    double vStep = 1.0 / m_nGridV;
    for (int i = 0; i <= m_nGridU; i++)
    {
        double u = i * uStep;
        for (int j = 0; j <= m_nGridV; j++)
        {
            double v = j * vStep;

            CPoint pt(0, 0);
            for (int k = 0; k < m_nOrderU; k++)
            {
                for (int l = 0; l < m_nOrderV; l++)
                {
                    double coeff = Bernstein(m_nOrderU - 1, k, u) * Bernstein(m_nOrderV - 1, l, v);
                    pt += CPoint(coeff * m_ControlPts[k][l].x, coeff * m_ControlPts[k][l].y);
                }
            }

            m_SurfaceGrids.push_back(pt);
        }
    }
}

double CMyView::Bernstein(int n, int i, double t)
{
    double coeff = 1.0;
    for (int j = 1; j <= i; j++)
    {
        coeff *= (double)(n - j + 1) / j;
    }
    for (int j = 1; j <= n - i; j++)
    {
        coeff *= t;
    }
    for (int j = 1; j <= i; j++)
    {
        coeff *= (1 - t);
    }
    return coeff;
}

最后，在OnDraw函数中，可以根据曲面网格数组绘制Bezier曲面：

void CMyView::OnDraw(CDC* pDC)
{
    // 绘制控制点
    for (int i = 0; i < m_nOrderU; i++)
    {
        for (int j = 0; j < m_nOrderV; j++)
        {
            pDC->Ellipse(m_ControlPts[i][j].x - 5, m_ControlPts[i][j].y - 5,
                m_ControlPts[i][j].x + 5, m_ControlPts[i][j].y + 5);
        }
    }

    // 绘制曲面网格
    CPen pen(PS_SOLID, 1, RGB(0, 0, 0));
    CPen* pOldPen = pDC->SelectObject(&pen);
    for (int i = 0; i < m_nGridU; i++)
    {
        for (int j = 0; j < m_nGridV; j++)
        {
            int idx1 = i * (m_nGridV + 1) + j;
            int idx2 = i * (m_nGridV + 1) + j + 1;
            int idx3 = (i + 1) * (m_nGridV + 1) + j;
            int idx4 = (i + 1) * (m_nGridV + 1) + j + 1;
            pDC->MoveTo(m_SurfaceGrids[idx1].x, m_SurfaceGrids[idx1].y);
            pDC->LineTo(m_SurfaceGrids[idx2].x, m_SurfaceGrids[idx2].y);
            pDC->LineTo(m_SurfaceGrids[idx4].x, m_SurfaceGrids[idx4].y);
            pDC->LineTo(m_SurfaceGrids[idx3].x, m_SurfaceGrids[idx3].y);
            pDC->LineTo(m_SurfaceGrids[idx1].x, m_SurfaceGrids[idx1].y);
        }
    }
    pDC->SelectObject(pOldPen);
}