Hi,
We have to manage some similar problems. We have different shaders and
different uniforms in the same
scene graph.
Some nodes have a cull callback. During the cull traversal, the callback
identify the current view/context
and push the corresponding state set in the render graph, traverse the
children and pop the state set.
On 23/10/2013 18:49, Robert Osfield wrote:
HI Paul,
If you have just a single uniform value per context then I'd simply
place the Uniform on the each if the viiewer's osg::Camera's StateSet,
such that each Camera assigned to each Context gets it's own state
inherited down including the Uniform.
If you want to put a vector of Uniform in the scene graph, then It
would probably be most robust to use a custom osg::Group node that
manages the cull traversal where it push/pops the approach Unifiorm as
well as any resizeGLObjectBuffers/releaseGLObjects etc. The key to
doing it thread safe is to make sure you have allocated the vector to
the required number of contexts prior to traversal - this is what the
resizeGLObjectsBuffers() helps with.
Robert.
On 23 October 2013 17:38, Paul Martz <[email protected]
<mailto:[email protected]>> wrote:
Hi all -- I've been inactive with OSG lately, but from time to
time get called back. Given my lack of recent experience, I would
appreciate your help with this issue.
I have a multicontext/multidisplay app that needs to compute a
uniform during cull, and it will have a different value for each
context/display. Computing the uniform value is straightforward,
but actually executing the uniform per-context during draw is
somewhat difficult.
I can't simply store the uniform in the Node's StateSet, for
example, because doing that during cull is not thread safe.
Ideally I would store the uniform in a vector indexed by context
ID, but I don't have a context ID during cull.
Would it be feasible to store the uniforms in a map indexed by
RenderStage address, then execute the uniforms from a Camera
per-draw callback?
Assuming I use a per-context or per-RenderStage container to store
the uniforms, how do I initially grow that container in a
thread-safe way during the first frame?
What are other people doing in this situation? Thanks in advance
for the advice.
--
Paul Martz
Skew Matrix Software LLC
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