directional constant usage. Added ability to render sprites in two
distinct layers.
git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@1132 542714f4-19e9-0310-aa3c-eee0fc999fb1
preparation for character component compositing and other
character-related antics.
git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@575 542714f4-19e9-0310-aa3c-eee0fc999fb1