public void Step() { var r = r0 + 5; var rmax = r0 + 10; Partical p = new Partical(); p.RndInit(r); while (true) { var dist = p.magnitude; if (IsSurround(p.position)) { SetPixel(p.position); if (dist > r0) { r0 = dist; } break; } if (dist > rmax) { break; } p.BrownianMotion(); } }