Question

openGL 如何同时在屏幕上画两个圆

Answer 1

glBegin(GL_POLYGON);
for (int j = 0; j <= n ; ++j) {
glVertex2f(c1.x + R1 * sin(2 * Pi / n * j), c1.y + R1 * cos(2 * Pi / n * j));
}
glEnd();

glBegin(GL_POLYGON);
for (int j = 0; j <= n ; ++j) {
glVertex2f(c2.x + R2 * sin(2 * Pi / n * j), c2.y + R2 * cos(2 * Pi / n * j));
}
glEnd();

c1，c2就是两个圆的圆心坐标了，R1，R2是两个圆的半径，用GL_POLYGON模式画图，取一个n值就行了