Hi Mark, yeah colors in MoI are a method you can use to organize your model into some different visual categories.
That kind of categorization can be used for a couple of different purposes.
One is that it serves as a type of grouping function so that you can turn on or off a whole set of objects with one click on an eye icon in the scene browser.
Another is that it allows you set up different material assignments for when you export your model to a rendering program. Each different style that you have in MoI will become one entry in the materials list in the rendering program, you can then adjust the material properties to alter the rendered appearance of those objects that have been assigned to that material. In MoI v1 before styles were present, you had to do all the material assignment inside the rendering program which can involve selecting a lot of different little pieces. That kind of selection intensive stuff can be easier to do as you are working on things during modeling time instead.
Check out this gallery item for a good demo of how Styles can be used to group objects:
http://moi3d.com/gallery/viewitem.php?id=278
See here for a full screen image:
http://moi3d.com/gallery/images/MOI_ATL_videata.jpg
So in the case above you can see there are 5 different large support beams on the bottom of that bridge that are colored red - they've all been assigned to belong to a style named something like "Main tubes" (the names are actually in Italian in that screenshot).
You can now hide or show all of those 5 large supports with a single click by going to that entry in the scene browser and clicking on the eye icon on the left hand side of the style's name in the style list. Or if you right-click on the eye, it will hide everything else and only have just those 5 objects showing so you can focus on them for some work that only involves just those objects.
By having categories like that it allows for multiple objects to be hidden, shown, locked, or selected all in one click so you can work on some predefined groups and batches of objects instead of having to actually pick them individually within the scene with the mouse every time you want to hide, show, lock, or select them.
The way that they are linked together is that they are all assigned to the same style, and the way that you operate on them as a linked group is by using the controls in the scene browser to operate on that style.
In some CAD programs this kind of thing is often referred to as "Layers".
Does that help make sense of it?
- Michael
