A port of the OpenSceneGraph project for Android and iOS is available on github as one of my repositories:
https://github.com/Eduardop/osg
The Android port has fixes to work on the latest SDK and NDK, and it uses shared C++ runtime.
With the iOS port, I provide a ready-made Xcode project -- useful if you're having cmake configuration problems.
The Android port is in the osg-android branch, and the iOS port in osg-iOS.
