Thanks for the bug report. I wasn't aware of that problem, but looking at the code, I see it. The Windows and Mac versions use cross-platform code to process the command line and generate snapshots when directed to do so. Unfortunately, the Qt (Linux) version has its own platform-specific code for doing this. I don't know right now if this is due to it not yet being updated to use the cross-platform code, or if it is because the cross-platform code doesn't work on the Linux version. (Note that someone else maintains the Linux version with my help, so I'm not an expert on it.)
I'll talk to the Linux LDView maintainer to see if he can update it to use the cross-platform command line snapshot code. If not, I'll give him the info needed to implement support for -ca and -cg. (Note: I believe that -SaveSnapshots=1 command line option also doesn't work in the Qt version.)
In the short term, I believe that you should be able to use the OSMesa command-line-only version of LDView. Either grab a built version of that, or build it yourself. Note that this version's executable is "ldview" (all lower case). It uses the cross-platform command line snapshot code, so it should properly support -ca and -cg, and it should have a working alpha channel. It should work with LPub.
I'll talk to the Linux LDView maintainer to see if he can update it to use the cross-platform command line snapshot code. If not, I'll give him the info needed to implement support for -ca and -cg. (Note: I believe that -SaveSnapshots=1 command line option also doesn't work in the Qt version.)
In the short term, I believe that you should be able to use the OSMesa command-line-only version of LDView. Either grab a built version of that, or build it yourself. Note that this version's executable is "ldview" (all lower case). It uses the cross-platform command line snapshot code, so it should properly support -ca and -cg, and it should have a working alpha channel. It should work with LPub.