[rrd-users] Stacking at Infinity

Chris Mason chris at noodles.org.uk
Sat Mar 3 13:44:25 CET 2012


> One line at the top (or bottom) of the graph, then stack a suffient amount
> in the "wrong" direction. I never tried it, but stacking -50M "on top" of
> 150M should get you at 100M.

So this works normally when not working at infinity:


I assumed the LINE would take into consideration the lines width when
stacking so I could use -1 as the value. This doesn't seem to work and
I have to use an actual value but this value would be dependant on the
scale of the data.

However, when I draw the first line at INF then it doesn't seem to
work and have looked into the possibility of achieving the desired
affect using TICKs as suggested by Martin:

> I remember that I have done so to highlight times when we have exceeded predictions.
> You could obviously paint multiple TICKS for different types and paint them with different colors using transparency.
> As the color (de)coding may be a pain you possibly could draw multiple ticks of different fractions.

This looks promising and I have used the following to get my desired affect:


** ifOutDrops is INF or NEGINF if drops detected.

This is so close to what I want to achieve, where each TICK is 1% of
the Y axis. To get a stacking affect I am overlapping TICKs with the
bottom one being slightly taller than the next one.

Now, this works if all classes have drops in, but in most cases they
don't and it is only a single class which has drops. If it was DS3 and
DS1 then the DS3 TICK would be visibly 2% tall as opposed to 1%.

Is it possible to calculate the fraction dynamically depending if I
have drops in the classes or is there an alternative approach?


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