pioneerspacesim/pioneer — pull request #1387 by johnbartholomew (2012-07-22 20:35:33+00:00)
Title: Fix planetary ring blending

This changes the planetary ring seed modifier so that Saturn gets a "Saturn-like" set of rings, and slightly tweaks that ring configuration. Previously it got a "Brown Dwarf-like" set of rings (which are more translucent, among other things).

It also changes the blending mode used when rendering the rings, which makes the shadowed segment of the ring slightly visible without adding an ambient light term as in #1351.

Before:
![Brown Dwarf style rings, with modified additive blending](http://i.imgur.com/l4pRZ.png)

After:
![Saturn style rings, with normal alpha blending](http://i.imgur.com/qqVLC.png)