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 CAD / MLCad / 2054
2053  |  2055
Subject: 
Re: Things that are hard to do with LDraw and building instructions
Newsgroups: 
lugnet.cad, lugnet.cad.mlcad
Date: 
Sun, 13 Mar 2005 14:12:36 GMT
Viewed: 
1179 times
  
In lugnet.cad, Don Heyse wrote:
In lugnet.cad, Michael Lachmann wrote:
In lugnet.cad, Kevin L. Clague wrote:
Whenver I build a LEGO model, I always pay attention to things that
they can do that we cannot, or we cannot do easily.  One of the
things that is very hard to do is, change the shape, orientation or
location of a part added in previous steps.

For that I've introduced the BUFFER EXCHANGE command, see developer
specification on my web-page
(http://mlcad.lm-software.com/Specification_V2.0.pdf).
With that you can do exactly that. You might need GHOST commands as well.
Also have a look at the
sample models "Waggon1", "Waggon 2" ... I've provided which makes use of
this features.

Yeah, in his first post Kevin said you could use Buffer Exchange
and Ghost to acheive the effect, but it's not easy.  This might
be because those commands work on a series of images, but he's more
comfortable thinking in terms of manipulating the model.  I know
I am.

Since LPub is not a renderer, it in fact does deal with models.  Buffer exchange
in LPub saves/restores the model up to the buffer exchange, not the images from
steps.


With images, you restore an old image state and rebuild all the
layers with some changes to get a new image.  That involves a lot
of repetition.  With the model you just change the bit you want
and let the speedy graphics board/engine redraw the whole thing.

0 SUBSTITUTE "original group, part, or line-number" "new group or part"

This gets tricky...... I don't know how you can create a new group that isn't
already in the model...  I simply think of the above as a removal of a group and
addition of a new part.

Groups can span steps, which makes it tricky to know where to put the
substituted group with respect to the steps.


This could redraw the entire model using the final version of the
hoses.

0 MOVE x y z  a b c d e f g h i "some group, part, or line-number"

I can see hoe this works though, because you can translate and rotate all the
parts within a group.  How do you specify the rotation point?


This would redraw the entire model with all the hoses somewhere else.

I was merely thinking of something like

0 LPUB REMOVE "some group"

from here I could add a new part, be it a fixed shape part or a composite part
like something LSynth would crank out.

I would enclose it in:

LPUB PLI BEGIN IGN
LPUB PLI END

or its depricated form:

PLIST BEGIN IGNORE
PLIST END


I've thought about this off and on ever since I tinkered with
accepting the ldraw file via stdin on ldglite.  I guess I always
wanted to turn it something you could run through a UNIX pipe.

cat foo.ldr macro.ldr | ldglite...

If all the LEDIT commands were implemented as meta-commands you
could do some really cool stuff with a pipe.

I've thought about pipes as well, where each segment of the pipe takes options
to modify the pipe's behavior.


Anyhow, it's something to think about.

Enjoy,

Don

Kevin



Message is in Reply To:
  Re: Things that are hard to do with LDraw and building instructions
 
(...) Yeah, in his first post Kevin said you could use Buffer Exchange and Ghost to acheive the effect, but it's not easy. This might be because those commands work on a series of images, but he's more comfortable thinking in terms of manipulating (...) (20 years ago, 11-Mar-05, to lugnet.cad, lugnet.cad.mlcad)

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