Optimize performance by skipping scene update when possible

[darksylinc]

Summary

IMPORTANT:

This PR depends on gazebosim/gz-rendering#415 and should not be merged until that PR is.

Ray queries (performed every time the mouse moves) had a negative
performance impact caused by
gazebosim/gz-rendering#415

This commit prevents repetead calls to IgnRenderer::ScreenToScene to
perform unnecessary performance degradation since calling
ClosestPoint(true) the first time during the frame is enough

Code will not compile until PR gazebosim/gz-rendering#415 is
merged

Signed-off-by: Matias N. Goldberg [email protected]

Summary

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
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[darksylinc]

Note: As I'm studying a few changes I noticed we may be able to optimize it back to pre gazebosim/gz-rendering#415 levels by calling this->HandleMouseEvent(); either before this->dataPtr->renderUtil.Update(); or after this->dataPtr->camera->Update(); and thus always calling rayQuery->ClosestPoint(false)

This would cause mouse events to lag behind by 1 frame; but no update of scene would be required (thus no extra CPU needed). Without gazebosim/gz-rendering#415; gazebo's GUI is currently operating on data that is behind by 1 frame anyway.

[chapulina]

Note that from Fortress, GzScene3D is being deprecated in favor of MinimalScene (still WIP), so we'll need to port this fix there). CC @ahcorde

[chapulina]

@darksylinc , are you still working on this?

[darksylinc]

I forgot about this but because I thought it was already merged.

If I understand correctly this code should be ported to MinimalScene now?

[chapulina]

If I understand correctly this code should be ported to MinimalScene now?

Yes, please 🙇🏽‍♀️ You're welcome to leave the code in GzScene3D too because Fortress users may still be relying on it.

[chapulina]

Scene3D has been removed from the gz-sim7 branch. So this needs to target MinimalScene on gz-gui. Closing.