Opacity is broken in Scalable Rendering Mode

[JustinPrivitera]

In 3.4.1 blueOS and toss4, scalable rendering mode with non-100% opacity is broken.

Here is a pseudocolor plot of d from multi_curv3d.silo with the opacity set to 20% in default rendering mode:

Here is the same plot with scalable rendering mode enabled:

Here is a filled boundary plot of mat1 from multi_curv3d.silo with the opacity set to 20% in default rendering mode:

Here is the same plot with scalable rendering mode enabled:

Another angle:

These plots worked correctly in 3.3.3.

To reproduce:

1. run visit in parallel
2. open multi_curv3d.silo
3. make a pseudocolor plot of d
4. change opacity to 20%
5. open options/rendering and turn scalable rendering mode to "always"

There are some large datasets on the SCF under /usr/workspace/visit/visit/bug_data that have these issues; we should ensure that for all of them this issue is resolved before marking this ticket as resolved. It is possible that those datasets may have additional issues that are not captured here.

[markcmiller86]

Yeah, I have a bad feeling we introduced some transparency issues in 3.4 with VTK-9.

[BenWibking]

I am seeing this issue with isosurfaces that have less than 100% opacity in 3.4.1.

Is this fully fixed by #19583? I have to ask the TACC sysadmins to re-build the VisIt module, so I want to confirm that this is really fixed. If there are nightly builds I can test, let me know.

[JustinPrivitera]

#19583 addressed this ticket but it sounds like there is another opacity issue affecting the first of the three user data sets (merged mili data set where low opacity makes it white). Should we open a new ticket for that? @brugger1 @visit-dav/visit-developers

[brugger1]

Yes, #19583 addressed the issue with the missing polygons and the horizontal bars, but there is still an issue with low opacity showing up white. I am looking into that.