Back face color confusion

[pbacot]

I just noticed something, thought I'd pass it along, or you can suggest what the best practice is.

I inadvertantly painted a back face using ThruPaint. I changed the front face color to DEFAULT material later. In Sketchup the color looks like the front face. But in rendering with Twilight the backface color showed. Correcting the backface also to default fixed the confusion.

In the end render you don't use default texture anyway so...

[Chris]

Because Twilight Render can only render 1 face, some logic is required to figure out what is the best choice. There are 3 rules, evaluated in order.

1. If a Front face is painted, that face is considered the front-facing face, and it's material is used.
2. Otherwise, if a Component or a Group is painted, the Front Face is considered the front-facing face and the group/component material is used (regardless of what the back face is painted)
3. Otherwise, and lastly, if the Back Face is painted, the Back Face is considered the front-facing face and the Back Face material is used.

Generally, it's always a good idea to make sure your Front Faces are what is exposed to the view. And if in doubt, paint the faces directly.

There is a side-effect to be aware of. If your render shows a back-facing face (not necessarily the SketchUp Back Face; it depends on how it's painted), your render may show odd results, typically a very reflective surface. So it's important to manage your faces carefully.