Hi Mikhail,
If you want to remove elements from the scene graph but delay
destruction to be done in a background thread the way to do it take a
ref_ptr to the subgraph you want to remove to prevent it from being
deleted, then remove the subgraph from the scene within the update
phase of the viewer frame, then pass this ref_ptr to the background
thread. Personally I wouldn't use co-opt the DatabasePager for doing
this - although it does supports this already, conceptually it doesn't
make for a clean application.
Robert.
On 17 February 2012 07:10, Mikhail I. Izmestev izmmish...@gmail.com wrote:
Hi,
To remove heavy in destruction objects (which will free large buffers and
etc.) I use method like in DatabasePager - hold object references and pass
they to another thread for destructing.
But there is one case which cause crash.
(root)
|
(some nodes)
(...)
| |
(nodeA) (nodeB)
\ /
\ /
(nodeC)
|
(...)
|
(nodeD)
So we have nodeC with two parents, and in some moment we want to delete
subgraph with nodeA.
We remove from graph parents of nodeA and hold it reference to be destructed
later in another thread.
Another thread decrease reference for parents of nodeA and initialize
destruction, so nodeA have no more references and it want to be deleted, it
inform children about that and request to remove it from parent list.
But in render thread we still render main graph and it traverse nodeC, but
someone like nodeD changed it's matrix, this process require to dirtyBound,
and dirtyBound inform all parents about this and tries to walk backward for
all parents and nodeA too.
So one thread iterate _parent vector, second thread change this vector, and
in result CRASH!
Looks like DatabasePager affects this problem too.
What you can advice in this case?
Mikhail.
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