Hi,
While modifying texture-atlases in DBPager threads we noticed an issue of
thread-synchronization.
Code like the snippet below (From Texture2D.cpp):
else if (_image.valid() && getModifiedCount(contextID) !=
_image->getModifiedCount())
{
applyTexImage2D_subload(state,GL_TEXTURE_2D,_image.get(),
_textureWidth, _textureHeight,
_internalFormat, _numMipmapLevels);
// update the modified tag to show that it is up to date.
getModifiedCount(contextID) = _image->getModifiedCount();
}
If another thread (like a DBPager thread) modifies the image of a texture (in
this case a texture-atlas which gets more and more images added to it while it
is also being applied on geometry), the modified count changes made by one or
more dirty() calls can get missed.
If the image got dirtied before the RenderThread tried to apply this texture,
code-execution enters the if() described above. If the texture upload takes too
long and the image is dirtied again, the effect of the 2nd dirty can be missed
when the modified count of the image is put into the texture.
A simple solution would be to use a local variable to store the image's
modified-count, and apply it to the texture. The overhead of a possible
redundant texture-upload on the next apply would be down-side. But
texture-atlases would support multi-threaded updates better.
Thoughts?
Thank you!
Cheers,
Anish
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=72188#72188
_______________________________________________
osg-submissions mailing list
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org
