[osg-users] Setting view matrix seems to lag behind on frame

[Robert Osfield]

Hi Sebastian,

On 1 December 2015 at 16:12, Sebastian Messerschmidt <
sebastian.messerschmidt at gmx.de> wrote:

> Sorry for answering my own question:
>
> The reason- of course- is threading. When setting the threading model to
> single-threaded the correct matrix is used in the frame.
>

I just had a look at the code, you don't set the DataVariance of the
osg::Geometry to DYNAMIC so when the viewer runs multi-threaded the vertex
update code can update the geometry whilst the previous frame is still
being rendered.  So rather than the camera lagging the geometry by a frame,
it's the geometry actually jumping ahead of the camera.

It's a subtle little bug but quite a good class example of the challenges
of trying debug multi-threaded applications :-)

Robert.
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