Topka posted a question about having gradient lines in Zabbix. It sounded like a fun hack and a few hours later it was done.

It's a fairly straightforward hack. When you create a graph you have the ability to add an item with it's line type of "Gradient Line". It will then take the color of the line you chose and create a gradient from that color to white/opaque below that line. The gradient goes from the line to the bottom of the graph. When there are jagged nearly vertical lines in the graph the gradient graph does not look very good. The was most often observed in testing with Processor load with a resolution of 5 seconds. Changing that to 15 or 30 improved quality on a 1hr graph.

The patch will work with any color and with multiple items. No Changes are needed to the database.

NOTE:
If your php version does not use true-color images gradient graphs will not work. I added some code to detect the use of true-color image functions. If your php does not use true-color you will only see a normal line. This is due to the need for an alpha channel and the way php handles color variables.

To apply the patch.
1) Save the patch to your system
2) Change into your Zabbix directory
eg "cd /srv/www/htdocs"
3) Apply the patch
patch -p1 < /path/to/your/patch/gradient.patch

Please post any problems encountered.