I enabled red/green/blue BFC checking for transparent parts in LDView 4.2B1 in order to allow part authors to sanity check the BFC of hard-coded transparent portions of parts. (I think Philo requested this.)
However, it can be argued that the main problem is an LDView bug (and one I was unaware of until now). Unfortunately, I'm pretty sure fixing it would require a great deal of effort, and I'm not sure it will be fixed even in the official 4.2 release. In LDView, BFC is disabled for transparent geometry, but it's not disabled for opaque geometry on transparent parts. One might argue that this geometry should be BFC NOCLIP, but I'm not sure if that argument flies. (I'm not entirely sure it doesn't fly either, which is why I'm not willing to commit to fixing LDView yet, and I'm not sure it's even an LDView bug.)
What does the real life part look like from the back? The pattern doesn't appear the same from the back side, does it? Isn't mostly the base coat visible from the back side? If so, it could be argued that this base coat should be drawn with BFC facing towards the part plastic, but that won't fly due to introducing co-planar polygons. These would look horrible any time BFC is disabled.
I would lean toward saying that pattern geometry that is designed for a known transparent part should be BFC NOCLIP. But this wouldn't solve the problem of using an opaque patterned part in a non-official transparent color, so LDView's behavior is still not optimal.
However, it can be argued that the main problem is an LDView bug (and one I was unaware of until now). Unfortunately, I'm pretty sure fixing it would require a great deal of effort, and I'm not sure it will be fixed even in the official 4.2 release. In LDView, BFC is disabled for transparent geometry, but it's not disabled for opaque geometry on transparent parts. One might argue that this geometry should be BFC NOCLIP, but I'm not sure if that argument flies. (I'm not entirely sure it doesn't fly either, which is why I'm not willing to commit to fixing LDView yet, and I'm not sure it's even an LDView bug.)
What does the real life part look like from the back? The pattern doesn't appear the same from the back side, does it? Isn't mostly the base coat visible from the back side? If so, it could be argued that this base coat should be drawn with BFC facing towards the part plastic, but that won't fly due to introducing co-planar polygons. These would look horrible any time BFC is disabled.
I would lean toward saying that pattern geometry that is designed for a known transparent part should be BFC NOCLIP. But this wouldn't solve the problem of using an opaque patterned part in a non-official transparent color, so LDView's behavior is still not optimal.