Screenshot algorithm removes transparency

[rainergericke]

While simple scenes with transparency look good on the screen, it looks quit different when written into a screenshot file. The transparency information gets lost.

In Project::Chrono we have a example showing a buoy swimming in water. The water graphics is transparent:

writing the screenshot we get this:

This issue could be seen on

1. MacOS Tahoe 26.2 (arm64 + built in gpu)
2. Windows 11 (AMD64 + NVIDIA GPU)
3. Ubuntu 24.04 (AMD64 + NVIDIA GPU)

We use the screenshot function contained in vsgscreenshot.

[robertosfield]

Curious. It doesn't look like the transparency is completely lost - you can still see the sphere, it's just that the water geometry is now white rather than blue.

No idea what is going on...