Question

在我的OpenGL程序中绘制七边形时遇到问题。我想在一个矩形内绘制一个七边形，到目前为止我可以绘制红色矩形，但七边形不会出现。

我不认为我需要转换为学位，除非我想要旋转它吗？这是我的代码：

void CChildView::OnGLDraw(CDC* pDC)
{
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    int width, height;
    GetSize(width, height);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, // left
        1.0, // right
        0.0, // bottom
        GLdouble(height) / GLdouble(width), // top
        1.0, // near
        -1.0); // far

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    glColor3d(1., 0., 0.);

    glBegin(GL_POLYGON);    // Rectangle
    glVertex2d(0.25, 0.25);
    glVertex2d(0.75, 0.25);
    glVertex2d(0.75, 0.75);
    glVertex2d(0.25, 0.75);
    glEnd();

    glColor3d(1., 1., 1.);

    int numPoints = 7; // Heptagon
    double x, y;
    double radius = 0;
    double centerx = 0;
    double centery = 0;

    glBegin(GL_POLYGON);

    for (int i = 0; i < numPoints; i++)
    {
        x = centerx + radius * sin(2.0*M_PI*i / numPoints);
        y = centery + radius * cos(2.0*M_PI*i / numPoints);

        glVertex2d(x, y);

    }
    glEnd();

    glColor3d(0., 1., 0.);

    glBegin(GL_LINES);
    glVertex2d(m_linefmx, m_linefmx);
    glVertex2d(m_linetox, m_linetoy);
    glEnd();

}

Answer 1

问题是radius被初始化为0并且从未改变，因此所有点都计算为（0,0）。

绘制2D Heptagon OpenGL

1 个答案: