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CompositeViewer support: Difference between revisions
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* Sharing a single window between multiple views is demonstated in the osgcompositeviewer example - you simply assign the same GraphicsWindow to the Camera's in each of the Views. You change views you can stop the viewer threads and then add/remove views you need then restart the threading, this will drop a few frames though due to stopping/start of threads. The other way is to switch off the rendering of the view by setting its Camera's NodeMask to 0x0 to disable it.<ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg18291.html</ref> | * Sharing a single window between multiple views is demonstated in the osgcompositeviewer example - you simply assign the same GraphicsWindow to the Camera's in each of the Views. You change views you can stop the viewer threads and then add/remove views you need then restart the threading, this will drop a few frames though due to stopping/start of threads. The other way is to switch off the rendering of the view by setting its Camera's NodeMask to 0x0 to disable it.<ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg18291.html</ref> | ||
=== Context sharing === | === Context sharing === | ||
The OSG allows you to create graphics context, make the context | |||
current and then dispatch rendering and do swap buffers yourself but | |||
this requires you to individually set everything up yourself. | |||
What osgViewer does is provide all the basic functionality that 99% of | |||
users need out of the box, including handling context creation, | |||
multiple contexts, handling of database threading, viewer threading, | |||
event handling etc. It makes what would be a complicated task | |||
trivial, but with encapsulating all this functionality it has to make | |||
some assumptions about the way it's used<ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg36853.html</ref> | |||
* It's possible to share contexts in the OSG [...] As for general desirability of share GL objects between contexts, yes it can reduce memory usage, but it forces you to use the OSG single threaded otherwise two contexts will be contended for the same resources that deliberately aren't mutex locked for performance reasons. There is also on a limited set of cases where drivers/hardware will actually share OpenGL contexts. <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg32676.html</ref> | * It's possible to share contexts in the OSG [...] As for general desirability of share GL objects between contexts, yes it can reduce memory usage, but it forces you to use the OSG single threaded otherwise two contexts will be contended for the same resources that deliberately aren't mutex locked for performance reasons. There is also on a limited set of cases where drivers/hardware will actually share OpenGL contexts. <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg32676.html</ref> | ||
* Neither the OSG or OpenGL can provide thread safe sharing of GL objects when sharing contexts. If you want to run multiple context with multiple threads you will have to keep these contexts independent. <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg75584.html</ref> | * Neither the OSG or OpenGL can provide thread safe sharing of GL objects when sharing contexts. If you want to run multiple context with multiple threads you will have to keep these contexts independent. <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg75584.html</ref> | ||
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* Sharing contexts is also something the forces a few limits on how you use the graphics contexts, such as it's only really safe to use them single threaded. <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg16791.html</ref> | * Sharing contexts is also something the forces a few limits on how you use the graphics contexts, such as it's only really safe to use them single threaded. <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg16791.html</ref> | ||
* If you are creating new graphics contexts and applying and old scene graph to it then you can't use the Texture::setUnRefImageDataAfterApply(true) feature of osg::Texture as this will discard the imagery once it's applied to all the graphics contexts that it knows about. <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg32658.html</ref> The typical problem is that the scene graph has been set up to unref texture images after apply so when it comes to reloading the texture images there aren't the to download. <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg34284.html</ref> | * If you are creating new graphics contexts and applying and old scene graph to it then you can't use the Texture::setUnRefImageDataAfterApply(true) feature of osg::Texture as this will discard the imagery once it's applied to all the graphics contexts that it knows about. <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg32658.html</ref> The typical problem is that the scene graph has been set up to unref texture images after apply so when it comes to reloading the texture images there aren't the to download. <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg34284.html</ref> | ||
=== Image Sharing === | === Image Sharing === | ||