# [ferret_users] pyferret - opacity, fill color for polygon command

```Hi ferreters,

I have tested some new features from the last pyferret 1.0.0
and especifically about controls on opacity and color definition.
Now I am wondering how to produce filled color plots with some opacity
```
(a feature that is widely used in plots that show spreads, as IPCC projections plots for example).
```
From the following example:
yes? def axis/x xaxis=i[i=1:100]
yes? let a1=SIN(x[gx=xaxis]/10)+0.3
yes? let b1=COS(x[gx=xaxis]/10 +10)
yes? let a2= a1+0.3
yes? let b2= b1+0.3
yes? plot/line=1/nolab a1,a2, b1,b2

How to fill between a1 and a2 with a first color and
between b1 and b2 with another color, with transparency ?

If you use
yes? plot/nolab/line=1 a1,a2, b1,b2
yes? go fill_between poly/over/palette=green/opacity=10 a1 xaxis a2
yes? go fill_between poly/over/palette=red/opacity=10 b1 xaxis b2
you get as attached image small lines surrounding each polygon.
--> polygon1.png
Verified by a simple
yes? let a={20,80,50}
yes? let b={10,20,60}
yes? polygon/fill/hlim=0:100/vlim=0:100/lev=(0,10,1)/opacity=10 a,b,1
yes? polygon/fill/hlim=0:100/vlim=0:100/lev=(0,10,1)/opacity=10/o a+3,b+3,1
yes? polygon/fill/hlim=0:100/vlim=0:100/lev=(0,10,1)/opacity=10/o a+6,b+6,1
--> polygon2.png

```
Another feature that would be great, could be the possibility to defined the filled color that is used by the polygon command from a qualifier as the qualifier color with 4 quartets. Currently, you need to define a palette file even for a single color definition.
```
Let me know, if I have missed something on this graphic topic
or if there are easy workarrounds.

Happy new year at all.
Regards
Patrick

--
LSCE/IPSL, Laboratoire CEA-CNRS-UVSQ
Data Analysis and Visualization Engineer
ICMC - IPSL Climate Modelling Centre
--

```

Attachment: polygon1.png
Description: PNG image

Attachment: polygon2.png
Description: PNG image