Subject:
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Re: LDD vs LDraw
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Newsgroups:
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lugnet.cad
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Date:
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Wed, 13 Dec 2006 22:20:38 GMT
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Viewed:
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2004 times
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In lugnet.cad, Chris Phillips wrote:
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In lugnet.cad, Timothy Gould wrote:
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Hi Chris,
Some of what you ask for in MLCad can already be done...
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That doesn’t surprise me; most of what I know about MLcad was learned by
trial-and-error.
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I have used LDD (a little) and MLcad (occasionally over several years) and
had already given this topic some thought, so here goes. If I were writing
a new CAD program, it would do everything MLcad can do today, plus:
- I like the way that LDD knows how pieces connect, and “snaps” them into place. OTOH, I have found MLcad to be difficult to consistently place parts at “integral” locations, regardless of the snap resolution. I need flexibility sometimes, but not nearly as often as I need the parts to line up correctly.
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This surprises me. I’ve never had a problem.
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I must be doing something wrong, but whenever I place a new part it seems to
appear in an arbitrary location in one plane, and doesn’t “snap” to an
integral plate height or 1/2 stud location. Even if I’m using the most
coarse snap settings when I insert a part, I usually have to switch to the
highest snap resolution, zoom in, micro-adjust the part alignment, then
switch back to coarse snap again. I’m sure I’m doing something wrong, but
I’ve never quite figured out how to do it right.
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Well, MLcad cannot click things into place. I’ve learned over the years to be
careful to add parts to the model when using course grid, and then switch to
medium or fine as necessary.
MLCad will allow you to place on whatever grid resolution you are currently at.
If you happen to be in fine, drag and drop some part. You will be allowed to
place using fine coordinates. This easily leads to lots of parts not even being
close to clicking together.
One thing I would like to be able to do is select a rotation axis other than
X,Y,and Z. I find it fastest to add parts with the normal orientation of X/Y/Z,
and then have to rotate the set of parts to some arbitrary angle.
If I need to adjust this chunk of parts, I have to bring the model back to the
original orientation, change and rotate back..... this can end up being messy.
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- Easier manipulation of hinged or axled sub-assemblies? Would be nice to be able to “play with” a model and have gears mesh, or tweak a hinge and have all of the affected pieces rotate in space. (I know that’s a tall order, but MLcad is soooo good already that there’s not much else missing.)
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You can sort of do this with submodels
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I guess I need to learn how to use them. But from a naive user’s POV,
MLcad’s “group” feature is intended for defining “sub-models”, and it’s
really all semantics beyond that. Maybe “group” should create a sub-model
automatically? I don’t know.
But I have designed models where (for example) I’ve clustered an axle and all
of its gears and collars as one sub-assembly. It would be nice to be able to
easily modify the sub-assembly by just double-clicking on the axle, instead
of having to manually extract it from the model.
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I still don’t get this.... submodels mean separate LDR files. In MLcad you can
have separate LDR files, or you can use MPD. To edit these sub-models you have
to switch files.
Groups is a collection of parts that you can treat as a unit without the use of
a separate file. They each have their use, although historically sub-models as
separate LDraw files has been used a large majority of the time.
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- I love LDView’s rendering, zoom and rotation capabilities for inspecting models. Would like to see that level of realism and ease-of-use built right into the CAD program itself.
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Apart from looking nicer I don’t think there’s any viewing that LDView can
do that MLCad can’t.
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The level of realism has distinct advantages in terms of being sure that
you’re using proper colors, or spotting small problems with parts placement.
And I love LDview’s ability to spin the model in space. (Release the mouse
button while dragging and the model spins forever.)
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Let’s not downplay the difference in rendering quality. I’m one of those
weirdos that create some of my parts in MLcad. MLcad’s renderer often shows
gaps between tri’s and quad’s that are not really there. LDView does not do
this. Furthermore MLcad does not have support for BFC checking. LDView’s
red/green mechanism for viewing BFC parts is very, very handy.
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- LDD does a better job of categorizing parts by default than MLcad. Would be nice if there was an easy way to find basic bricks, plate, tile, Technic, etc. without having to dig through a million “brick with xxxx pattern” items. The Favorites folder in MLcad helps, but could be refined to improve the initial “out-of-box” experience.
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This can be done by setting up your part filters properly. I can’t remember
the details but I’m sure some other .cad denizen will.
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I don’t doubt that there’s a way to do it, but it isn’t obvious to the casual
user, and the default organizational tree is not as well organized as LDD.
(In all fairness, LDD is dealing with a pre-defined, limited subset of parts,
but still...) I think if there was an easy way to define a “virtual parts
bin” and share these with others as a separate file, it would be a very
useful feature. Depending on what I’m trying to design on any given day, it
would be nice to just select a parts palette with a certain organization and
start building. It shouldn’t be necessary to completely re-configure the
entire CAD program just to do this kind of thing for each project.
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MLcad’s organization is a direct map of the part naming methodologies that the
LDraw database follows. It literllay parses the name to put things into groups.
It works for me, but I don’t spend much time using plates, tiles and non-technic
bricks.
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- Easier hierarchical model editing. If I need to edit a sub-assembly in MLcad, must move it somewhere, un-group, edit, re-group, then replace. This becomes a nightmare with nested group hierarchies. Would be nice if I could easily edit a group in its own window without having to temporarily disband the group or use multiple DAT files.
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Submodels do all this. Using groups instead of submodels seems like asking
for problems.
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Good advice! Again, I must learn how to use them. Maybe MLcad shouldn’t
have groups, but should only support submodels? Or is there another intended
use for groups that I am missing?
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You just need to use the previous version of MLcad!
I think that groups and sub-models are different tools that serve different
needs. Sub-models end up being one part usage line (a type 1 line) in a file.
A group allows you to lump together parts sparsely added across the entire LDraw
file.
For building instructions groups have no meaning. Only sub-models have an
affect (you can get separate building instruction pages, or callouts (small
images that are assembled in place next to the main model on the pave)).
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I’m not trying to be critical of the existing tools, but it seems that some
of my problems are caused by my own lack of RTFM, some are a result of
unclear/missing documentation, and some are a case of being baffled by
overlapping (and seemingly identical) features. As a software engineer, I’ve
found that there is a big difference between “you can already do that” and
“it is obvious and painless for anyone to do that.”
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There are always areas for improvement. I didn’t get any sense of you being
cynical.
Your best bet for documentation is one of the two books on the LDraw family of
tools. Go to the LDraw web site and they show you both books. I co-wrote the
“LEGO Software Powertools Book”. Other important and prominent members here
worked on the the book “Virtual LEGO”. Both books are very good, and yet both
are out of date. MLcad has not changed a lot since the books were written
however.
There have been improvements in ldglite, LDView, LPub, LSynth, and other
important LDraw tools since these two books were published.
Kevin
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Message has 2 Replies:
 | | Re: LDD vs LDraw
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| (...) I have a question about this. It is very important to me. I like to make animations, and to rotate things correctly, I must use submodels. In using other people's models, I've discovered that nobody centers their submodels to the pivot point, (...) (18 years ago, 13-Dec-06, to lugnet.cad)
| | | Re: LDD vs LDraw
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| (...) Try LeoCAD... it allows to rotate parts around their own coordinate axis ;o) Philo (18 years ago, 14-Dec-06, to lugnet.cad, FTX)
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Message is in Reply To:
| | Re: LDD vs LDraw
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| (...) That doesn't surprise me; most of what I know about MLcad was learned by trial-and-error. (...) I must be doing something wrong, but whenever I place a new part it seems to appear in an arbitrary location in one plane, and doesn't "snap" to an (...) (18 years ago, 13-Dec-06, to lugnet.cad, FTX)
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