Need help with custom element tweaks

[Steve Barile]

Hi All,
A little background. I'm a long time AFOL train head. I ran BrickFest a few times in Portland. Worked together on the Hobby Train project with Tim Gould... now I run altBricks. I know enough about LDraw / MLCad to get around pretty well when it comes to model making and rendering and laying out instructions. But now I need two custom elements for altBricks so I can make instructions using them and post the .dat files for others that want to virtually build with these elements.






I created them already (linked) but think they need some tweaking from someone who is good at element creation. Here's the list of things needed:
1) Stud holes (tubes) on the bottom. I didn't add these cause for rendering they aren't seen much (but should be there).
2) The thickness on the bottom should equal a tile, they don't now.
3) The width of the remaining 3 sides need to be consistent and equal to the width of the newest LEGO windows.

I would be happy to send some altBricks stuff for the effort, if that's of interest we can work that out offline.
Thanks
SteveB

[Max Martin Richter]

I'll have a look at both parts tomorrow...

/Max

[Max Martin Richter]

I hope the result is OK for you. I found no other way to create the cross, because I didn't know the thickness and it was impossible to see anything on these tiny thumbnails. ;-)

/Max

[Magnus Forsberg]

If these were on the PT I would Hold vote them.

There are some better, bigger pictures at altBricks homepage.

1 x 3 here and the 1x2 here

All the beams in the crosses should be straight and they seem to go from side to side rather than corner to corner

[Max Martin Richter]

Mmh, indeed. I haven't check the WWW for better pictures. If wanted, I will rework both files.

/Max

[Steve Barile]

Hi Max,
Thanks a ton for helping out. I noticed a few things.

1) For some strange reason stug3-1x2 is not on my system. I noticed that both 3623/3622 parts use 2 separate stud3.dat primitives. I wonder if you uncovered an LDraw Library installer bug or somehow I deleted this from my system???

2) When dragging the element around in MLCad there are 6 quads that "poke" out the side of the model. Is this normal or ??? It's totally OK assuming they aren't rendered etc... These parts are for folks to design with these elements and so i can provide instructions using them.

3) Generic question which app do you use to author parts? I can't seem to figure out how to use MLCad to scale a primitive visually and I haven't understood the algorithm to calc the rotation matrix for rotations and scaling. Any tips?

SteveB

[Chris Dee]

1) For some strange reason stug3-1x2 is not on my system. I noticed that both 3623/3622 parts use 2 separate stud3.dat primitives. I wonder if you uncovered an LDraw Library installer bug or somehow I deleted this from my system???

The primitive stug3-1x2 was released in the latest Parts Update (2013-02) in December 2013. Maybe your library is not quite up-to-date?

[Max Martin Richter]

Hej Steve,
your welcome. What's about the shape issue? Should I change anything?

1) Chris gave the correct answer - Maybe you should update your system. ;-)

2) That's quite strange. I have the same problem in my MLCad, but the parts are correct modelled. I check this twice now. I really do not have a useful solution for this problems. So be a problem might be MLCad.

3) Well, I'm quite oldschool when creating parts. I use a simply text editor (LDraw Design Pad) and poll the results with LDView. So it's written by hand. Concerning the rotation matrix. In the beginning I had the same problem, but as a result of practice and time, it's not so hard anymore. (BTW, there had been some lines your files, that show me, you'd used MLCad.) :-)

/Max

[Philippe Hurbain]

Both parts look good to me, in LDView and in MLCad...

I can't seem to figure out how to use MLCad to scale a primitive visually and I haven't understood the algorithm to calc the rotation matrix for rotations and scaling. Any tips?

I am afraid that there is no other method than the one I described here - granted, it hardly qualifies as "visual"!!!

[Steve Barile]

Thanks for the response Max!

1) Would you be willing to make a tweak and use the 2 separate stud3.dat primitives? This way if anyone else has this issue I would NOT have to tell them to update there LDraw part dir. :-)

3) Is there a tutorial on how to calc the rotation matrix? I recall someone saying they use a spreadsheet to automate the matrix. In other words they enter XYZ scaling and rotations in 6 separate cells... and it generates the matrix. Have you ever heard of this?

Thanks
SteveB
PS is there a way to email someone directly via the LDraw site? Max, I'd like to chat privately.

[Max Martin Richter]

1) Yes I can to this. (I'll do it later this day).
I don't like this solution but if you request it... (Normally any user should try to get the updates. It's only two or three times a year, when they will be released.)

3) Sorry, I can not help you in this question. :-(

You can send me a mail to max_martin.richter (at) tu-dresden.de.

/Max

PS.: You can send me an email to 'max_martin.richter (at) tu-dresden.de' .

[Chris Dee]

1) Would you be willing to make a tweak and use the 2 separate stud3.dat primitives? This way if anyone else has this issue I would NOT have to tell them to update there LDraw part dir. :-)

I think you would need to give advice about what minimum version of the LDraw Parts Library they need to be at, effectively saying "These parts need library version 2008-01 or later", rather than saying that they don't need to update their library at all (and actually these parts won't render correctly with a 2008-01 library as they use other primitives that were introduced since then). It is not trivial to determine at what back-level version of the LDraw Parts Library any particular part would be rendered correctly. Far better to advise your users that they must have the version that was in use by the developer at the time they were developed (i.e. 2013-02).

[Steve Barile]

Hi Chris,
Thanks for the tip
Steveb

[Steve Barile]

Max,
Thanks for being flexible and thanks for the edit!
SteveB

[Max Martin Richter]

Sorry for the delay. I was quite busy the last days.
Here it is.

/Max

[Steve Barile]

Awesome!
Thanks
Steve

[Michael Heidemann]

3) Is there a tutorial on how to calc the rotation matrix? I recall someone saying they use a spreadsheet to automate the matrix. In other words they enter XYZ scaling and rotations in 6 separate cells... and it generates the matrix. Have you ever heard of this?

That should not be too difficult
There are two different aim that the matrix can do for us:
1) SCALING
Just take the the unity matrix 1 0 0 0 1 0 0 0 1 and change the value 1 to 2 if you want to double the size etc.
1 0 0 0 2 0 0 0 1 for example will generate a double hight (y-axis) part.
2) ROTATION
That is more difficult as you have to calculate depending on the angles of rotation each value. I found a webside that will do that for you (http://tools.wikimedia.de/~dschwen/tools...0%2Cz%3A50)

I hope this helps