how to add arrow up/down when lines cross?

[randomx]

hi all,
bullish: how do i add an green arrow up when the super fast line comes from below crossing the other two lines?
bearish: how do i add an green arrow down when the super fast line comes from above crossing the other two lines?

thank you in advance

input price = close;
input superfast_length = 8;
input fast_length = 13;
input slow_length = 21;
input displace = 0;


def mov_avg8 = ExpAverage(price[-displace], superfast_length);
def mov_avg13 = ExpAverage(price[-displace], fast_length);
def mov_avg21 = ExpAverage(price[-displace], slow_length);


#moving averages
Plot Superfast = mov_avg8;
plot Fast = mov_avg13;
plot Slow = mov_avg21;

 

[Pensar]

hi all,
bullish: how do i add an green arrow up when the super fast line comes from below crossing the other two lines?
bearish: how do i add an green arrow down when the super fast line comes from above crossing the other two lines?

thank you in advance

input price = close;
input superfast_length = 8;
input fast_length = 13;
input slow_length = 21;
input displace = 0;


def mov_avg8 = ExpAverage(price[-displace], superfast_length);
def mov_avg13 = ExpAverage(price[-displace], fast_length);
def mov_avg21 = ExpAverage(price[-displace], slow_length);


#moving averages
Plot Superfast = mov_avg8;
plot Fast = mov_avg13;
plot Slow = mov_avg21;

@randomx Here's something to add to your code. You can use as-is or change the conditions.

plot cross_above = mov_avg8 crosses above mov_avg21 and mov_avg13 < mov_avg21;
cross_above.setpaintingstrategy(paintingstrategy.boolean_arrow_up);
cross_above.setdefaultcolor(color.cyan);

plot cross_below = mov_avg8 crosses below mov_avg21 and mov_avg13 > mov_avg21;
cross_below.setpaintingstrategy(paintingstrategy.boolean_arrow_down);
cross_below.setdefaultcolor(color.magenta);

 

[randomx]

that's it, that's the one! thank you again