The first part of the fix is to assign VBO/EBO's upon loading the array in the Nif reader. This avoids triggering the 'addVertexBufferObjectIfRequired' code path in osg::Geometry which has the race condition when two threads add the same Array at the same time. Essentially, we want the Arrays to be 'const' when they come out of the Nif reader.
The second part of the fix is to make sure not to create empty arrays in the Nif reader (importantly, not assigning a VBO to the empty array). This empty array would be deleted when the NIFFile is cleaned up, and the detachment of the VBO assigned to it (which is still in use by other arrays) would cause threading issues.
This rare crash bug was first introduced with commit a7c5beb7c5. When using OSG dev version 3.5 the crashes were a little more prevalent, because 'addVertexBufferObjectIfRequired' in osg::Geometry is now used even when VBO's are disabled (as part of the VAO support changes).
The previous commit broke some magic effects (e.g. shield). The controller's emit start/stop times should control the emitter, while the absence of the ParticleSystem's autoplay flag should freeze the whole particle system if no valid controller source gets assigned. This revised version works for both the Shield effect and the "dagoth ur death sparkles" effect.
Since commit e8662bea31, we're using OSG functionality that contains an unfixed crash bug in version 3.2. The bug is fixed in version 3.4 (OSG commit 6351e5020371b0b72b300088a5c6772f58379b84)
Instead use getImage and let the caller create the Texture. Sharing of textures is then handled in post by the SharedStateManager.
This is closer to what the OSG serializer does.
Streamlines the TextureManager and will make it easier to multithread.
