BillboardChain not (always) facing camera

[rhaschke]

We use a BillboardChain to show various line strips in rviz: ros-visualization/rviz#1287 (comment)
However, camera updates are not correctly considered when rendering the BillboardChain: we can look "behind" the billboard, because the object is not camera-facing as it should.
Only if the same scene is rendered into a RenderTexture (when the mouse gets into the aabb of the BillboardChain), the camera pose is updated and the object correctly displays again.
We use Ogre::Root::renderOneFrame() to render the scene into all RenderTargets. Doesn't that call the required update() methods?
Any hints on what is missing are highly appreciated.

screen-recording.mp4

[rhaschke]

This seems to be an issue with OGRE 1.9 only (still the default for ROS in Ubuntu 20.04). Updating to OGRE 1.12 this works!
Any ideas, how to fix this in rviz with (existing) OGRE 1.9? E.g. calling some update() manually?

[paroj]

no idea. I am afraid you will have to git bisect for the fix.

Closing as it is fixed in master.

[rhaschke]

I would like to reopen this issue: Preparing a git bisect, I noticed that the bug is still existing in OGRE 1.12.4 (Ubuntu 20.04 system version). It seemed to work last time I checked, because I explicitly updated/recreated the BillboardChain frequently.

I verified that BillboardChain::preRender and thus BillboardChain::updateVertexBuffer are frequently called for rendering, which I assume are responsible for updating the view. However, the line isn't facing the camera...

[paroj]

does this also happen with a BillboardSet? chain and set are using different methods to obtain the current camera

[rhaschke]

No idea. Our code doesn't use BillboardSet.

[paroj]

you could try using it at the same place where you use BillboardChain to mark the vertices or something.