Paraboloid

void paraboloid(int slices, int subdivisions, int height)
{
    int   h, i;
    float alpha;
    float fh;
    float dh = (float)height / (float)subdivisions;
    float dx = PI2 / slices;
    glBegin(GL_TRIANGLE_STRIP);
    for (h = 0, fh = 0.0f; h < subdivisions; h++ ,fh += dh)
    {
        for( i = 0, alpha = 0.0f; i <= slices; i++, alpha += dx)
        {
            glVertex3f( fh * cosf(alpha),        fh * fh,              fh * sinf(alpha));
            glVertex3f((fh + dh) * cosf(alpha), (fh + dh) * (fh + dh), fh * sinf(alpha));
        }
    }
    glEnd();
}