About UnitCells

Development
1

Geoff,

just for the record: I owe you a beer for commit 499!

In schools, it is really important to be able to show how unitcells
work. For example, how the translation works.

With the crystallographic files I have I can already demonstrate the
"layers" in some crystals. This is really important, for example to
demonstrate why graphite layers can glide/slide (don’t know the
correct english term).

Two comments. The missing killer feature is this:

http://upload.wikimedia.org/wikipedia/commons/5/50/Graphit_gitter.png

Of course, it won’t be easy to implement. Both the “each layer is easy
to distinguish from the other layers” and the “draw spotted lines
between layers” won’t be easy, I bet…

Second, I find the UnitCell settings a bit unintuitive to find. For
all tools, the “configuration” is in the sidewidget. For the
UnitCells, it is in a dialog which you open in a menu. You cannot even
keep the dialog open as there is no “Apply”-button.
I understand the reason for this (the sidebar is for
tool-configuration while the unitcell-stuff is an extension). Still, I
think we should discuss how to improve this. Perhaps it is just me :slight_smile:

Ok, I will now try to add the apply button.

Carsten

2

Carsten,

Of course, it won’t be easy to implement. Both the “each layer is easy
to distinguish from the other layers” and the “draw spotted lines
between layers” won’t be easy, I bet…

That picture requires a few things, none particularly hard for the
future.

  • One is the “polyhedra” engine, which draws a plane through a ring
    like that.
  • One is the spotted lines (i.e., adding monitors or markers which
    are not atoms or bonds).
  • One is to allow bonding across unit cells. (Tricky, but should be
    possible.)

The first two are pretty easy IMHO. The third takes some time, but I
have some ideas.

UnitCells, it is in a dialog which you open in a menu. You cannot even
keep the dialog open as there is no “Apply”-button.

I don’t think we actually want an Apply button. I’d rather send
signals when the spin boxes change, and then “Cancel” reverts to the
previous settings. But I didn’t have time to do that yet. I also want
to add another section to the box, which lets you change the a, b,
and c lengths and the alpha, beta, gamma angles. That should be good
for now.

Cheers,
-Geoff