A previous GCI 2014 task resulted in an ebuild for libsoy. While this works, it needs a lot more work which may include working on other ebuilds as well:

• The waf eclass is not included, resulting in unnecessary functions below
• The license is incorrect
• The dependency on mesa excludes this working for other OpenGL libraries, including Raspberry Pi
• Older versions of valac are also supported
• gdk-pixbuf is not used directly by libsoy
• RDEPEND is not specified

While working on this task you should join and remain in #CopyleftGames on Freenode to get help, feedback, and guidance from mentors and other developers.

When you've done, post your ebuild to this task.