We are running into a problem with putting objects with transparencies inside a
sphere with a transparency.
The idea was to be able to look around while inside a sphere with a background
texture with transparency, and have another sphere beyond the first with auto
rotation to simulate clouds drifting in the background of the scene. What we
found were objects rendered inside the beyond the origin will show the
transparent sphere object texture in front of objects closer to the camera.
There is an example here:
which has the java source code included in the jar.
The inner sphere, with the alpha component, is at radius 29, Color(255,0,0,127),
the outer sphere is at 30 and white (no alpha), and the 2 transparent windows
are at -.4 and .4 on the Z axis. I also added a ground texture to show that
images without an alpha component between the window and the spheres turn off
the odd rendering.
If you pull the windows closer to you, than origin, the problem vanishes, if you
push them beyond origin, it reappears.
Turning off View.setTransparencySortingPolicy(View.TRANSPARENCY_SORT_GEOMETRY)
causes the front window to never show the bug, and the rear window to always
show the bug without regard to location.