Hello, I am using Rhino 6 via parallels desktop on Windows.
My preview picture of the object is always too dark in the rendering view. Maybe someone can help me?
I assume you mean you are using Rhino 6 for Windows using a Windows version running via a Parallels version running on some kind of Apple hardware with OSX? (There are ways of running Parallels on other hardware, so I want to be sure you are doing the most popular thing.)
The problem is that even the most recent version of Parallels does not provide the level of OpenGL that Rhino 6 requires for it’s display, which is a significant rewrite of the version 5 display system. Rhino 5 usually ran pretty well under Parallels even though McNeel doesn’t officially support Rhino running on ANY virtualization system.