本代码参考自《计算机图形学》第4版，根据极坐标参数方程绘制曲线：蜗形线、心形线、三叶曲线、四叶曲线、螺旋线共5种图形。

生成定点坐标的程序如下所示，该函数将需要绘制的顶点按顺序添加到入参verts的最后

typedef enum { LIMACON = 1,                 CARDIOID,                 THREELEAF,                 FOURLEAF,                 SPIRAL  } curveName; void GLApp::genVertices(std::vector
     
       &verts, GLint curveNum, const GLint x0, const GLint y0){    const GLdouble twoPi = 6.283185;    const GLint a = 175, b = 60;    GLfloat r, theta, dtheta = 1.0 / float(a);    glm::vec2 curvePt[2];    curvePt[0].x = x0;    curvePt[0].y = y0;    switch (curveNum) {    case LIMACON:        curvePt[0].x += a + b;        break;    case CARDIOID:        curvePt[0].x += a + a;        break;    case THREELEAF:         curvePt[0].x += a;        break;    case FOURLEAF:        curvePt[0].x += a;        break;    case SPIRAL:        break;    default:        break;    }    theta = dtheta;    while (theta < twoPi)    {        switch (curveNum) {        case LIMACON:            r = a * cos(theta) + b;            break;        case CARDIOID:            r = a * (1 + cos(theta));            break;        case THREELEAF:            r = a * cos(3 * theta);            break;        case FOURLEAF:            r = a * cos(2 * theta);            break;        case SPIRAL:            r = (a / 4.0) * theta;            break;        default:            break;        }        curvePt[1].x = x0 + r * cos(theta);        curvePt[1].y = y0 + r * sin(theta);        verts.push_back(curvePt[0]);        verts.push_back(curvePt[1]);        curvePt[0].x = curvePt[1].x;        curvePt[0].y = curvePt[1].y;        theta += dtheta;    }}
     

绘制时调用glDrawArrays(GL_LINES, 0, vert_num);

（vert_num等于verts.size()）