              }
                }
                octx.putImageData(img, 0, 0);
                return oc;
            }
            const planetImages = planets.map(p => createPlanetImage(p.radius, p.colors));

            // 离屏 Canvas 用来画固定不变的轨道线
            let orbitCanvas, orbitCtx;
            let cw, ch, cx, cy;
            function resize() {
                cw = canvas.width = window.innerWidth;
                ch = canvas.height = window.innerHeight;
                cx = c