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CompositeViewer support: Difference between revisions
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→Threading
m (→Swap Buffers: https://groups.google.com/g/osg-users/c/cIMLA2zkdyE/m/cUx9JZA2J4MJ) |
m (→Threading) |
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additional mechanism for holding back the next frame. There are | additional mechanism for holding back the next frame. There are | ||
mechanisms for doing a swap ready check for multi-context systems <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg72040.html</ref> | mechanisms for doing a swap ready check for multi-context systems <ref>https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg72040.html</ref> | ||
As for general notes about threading, if you are working on the same | |||
graphics context as you are then all the draw dispatch and the draw | |||
GPU can only be done by a single graphics thread so there is little | |||
opportunity to make it more parallel without using another graphics | |||
card/graphics context and interleaving of frames. | |||
Cull and draw can only run in a parallel once all the dynamic geometry | |||
has been dispatched, otherwise the draw will be dispatching data that | |||
is being modified by the next frames update and cull traversals. | |||
Perhaps you have some dynamic geometry or StateSet's that are holding | |||
back the next frame.<ref>https://groups.google.com/g/osg-users/c/JY1mVGofOEg/m/8P7j5titqVcJ</ref> | |||
There are limits with the time of threading you can do with cameras | |||
that share the same graphics context - the draw traversals has to be | |||
single threaded for each camera's rendering, this applies to FBO's as | |||
well as normal rendering to a graphics window. | |||
You should be able to still run multi-threaded if you have multiple | |||
graphics contexts, but the osgdistortion example just uses on graphics | |||
context, and multiple FBOs. <ref>https://groups.google.com/g/osg-users/c/RYEOlTMItbI/m/SQSrf0f5jXoJ</ref> | |||
You can have a slave Camera in the Viewer that is used a prerendering | |||
camera or a Camera in the scene graph that is used a prerender camera. | |||
Cameras in the scene graph are treated almost exactly the same way as | |||
slave Camera, it's just high level things like threading and how the | |||
view and projection matrices are assigned per frame that differ. <ref>https://groups.google.com/g/osg-users/c/RNgKAZTCyN0/m/kGPsRpxLlWQJ</ref> | |||
If you want to create and chain RenderStages then using an osg::Camera | |||
in the scene graph is often one of the best ways to do this, and use | |||
the Camera::setRenderOrder(..) to control the order. You can also use | |||
a custom cull traversal callback to create RenderStage/RenderBin and | |||
assign these to the rendering backend, but this does require a greater | |||
knowledge of the internals of the rendering backend.<ref>https://groups.google.com/g/osg-users/c/45_bw3QUELs/m/aXvWKsuKKgUJ</ref> | |||
=== Scene Modification === | === Scene Modification === | ||