Fallenangel, on 21 January 2012 - 03:32 AM, said:
From what I've heard, such a feature would be too complex to implement in LDD and it would be more sensible to simply switch to LDraw.
It's not very hard to implement. In fact, the LDD developers have an internal debug version of LDD that does just that, and they use it to be able to open those "UnplaceableBricksDump.lxfml" to view offending bricks. So why haven't they enabled that as a switch on/switch off feature for regular uses? I see three reasons
1) LDD is a tool for consumers. Sure, with the removal of DbM and LU, the strong focus on children can be losened somewhat, but it's still primarily a tool for LEGO consumers - not advanced AFOL MOC:ers.
2) If a certain builder uses collision control off, and then another is in "on" mode and they share files...there will be a problem when bricks are removed
3) By not allowing it, builders are forced to use legal techniques. Sure there are a few cases we LDD users have discovered where official sets are using illegal techniques, but those are very, very few and are a result of miss in the internal TLG model review process.
So why is TLG forcing legal techniques, even in a CAD tool?
Because illegal techniques destroy the bricks. Plastic (which is a polymer), is a very odd material. Unlike metal, it can permanently stretch even a room temperature and moderate loads. LEGO will not incorporate connections in their sets that will over time destroy the form or clutch power of the bricks - and I guess they don't want to enable consumers to make illegal builds in a CAD tool either. It's just a matter of principle. Sure LDraw tools can allow that, but they are not a corporation with responsibility in the same was as TLG.
Personally I actually like this "side effect" of LDD that you can only build legal, since I'm not a big fan of some of the MOCs you see nowadays and that are called "fantastic work"; with bricks that are not fully connected, things attached at an angle, or pieces that models that sometimes won't hold together if you touch them. Besides, for me LDD is a tool for the design process, and that is where its strength lies - you can quickly work with ideas in preparation for the physical build, and then the snap-together feauture makes all the difference in the world, since it makes LDD ultra fast to build with.
About the bug that Aleluca reported. That has nothing to do will illegal or not illegal - it's just a plain ol' nasty LDD bug
And the technique to attach those two bricks is actually not illegal per se - it's when you place another brick ontop of them that it becomes illegal (because of the reason explained by Aanchir and others).
Now, why TLG accepts a 1x1 plate or 1x1 round plate to attach to a technic hole, or even a 1x1 Round brick, but NOT 1x1 Bricks, I don't know