Pine-script如何获得交叉点的y坐标

//@version=4
study(title="交叉点的y坐标示例", shorttitle="交叉点y坐标", overlay=true)

// 定义两条指标线
line1 = sma(close, 10)
line2 = sma(close, 20)

// 判断交叉点
crossUp = cross(line1, line2) and line1[1] < line2[1]
crossDown = cross(line2, line1) and line1[1] > line2[1]

// 绘制指标线和交叉点
plot(line1, color=color.blue, title="线1")
plot(line2, color=color.red, title="线2")
plotshape(crossUp ? line1 : na, title="上交叉点", location=location.belowbar, color=color.green, style=shape.triangleup, size=size.small)
plotshape(crossDown ? line1 : na, title="下交叉点", location=location.abovebar, color=color.red, style=shape.triangledown, size=size.small)

// 获取交叉点的y坐标
crossUpY = valuewhen(crossUp, line1, 0)
crossDownY = valuewhen(crossDown, line1, 0)

// 打印交叉点的y坐标
plot(crossUpY, color=color.green, title="上交叉点的y坐标")
plot(crossDownY, color=color.red, title="下交叉点的y坐标")