TotiGonzales

It wasn't hard to find the right composition of the transformation line, but I first had to copy one of the existing ones or I could have copied one from the how to, doesn't matter, and than paste ti in. Than I had to adjust all the fields and figure out what goes where. If you could just add this here into your how to, it would be for everyone, I suppose, much easier to write a new transformation: <!-- Part name and partnumber.dat --> <!-- OFICIAL LEGO PART NAME and number --> <Transformation ldraw="LDraw part name.dat" tx="0" ty="0" tz="0" ax="1" ay="0" az="0" angle="0" /> Please correct it if that isn't right!

So... I really needed this piece: Part#: 15362 Name: CLAW 7 MODULES WITH CROSS AXEL. It wasn't inside LDraw's parts folder (not even inside the Unofficial parts Folder), but I found it here http://www.digital-bricks.de/en/index.php?site=1392 . I inserted a new line for it in the XML file (witch wasn't as straight forward as I expected, you should add a "template" for adding new parts in your original post) and it works/looks perfect if you would ask me. The question is: how could we make parts like this one accessible for everyone that needs them trough the XML file or through this forum? Teodor PS: On the website listed above are a lot of unavailable parts free for download.

Of corse i.j=k !!! I just had to look back a couple of lines! Thank you very much! Now I finally understand it all. Your how-to is perfect the way it is right now, I'm just too curious...

Thank you very much for explaining to me every thing I asked about. As I thought all my problems were pretty easy to solve. (I can't believe it didn't came to my mind that π/2 is 90° and that my calculator needed the degrees!) Now, I took another look at your examples and (I really don't mean to make you flip out or so, but...) this is as far as I got: p.q = (0 + i) . (√2/2 + √2/2 j) = √2/2 i + √2/2 i.j = 0 + √2/2 ( i + k ). I really can't figure out how √2/2 i + √2/2 i.j becomes 0 + √2/2 ( i + k )! ( the (i + k )...) I'm sure it's just some 5th grade math that I'm missing but I'm sick of getting quaternions nightmares because I try to get my head around this before I go to sleep. So I'll just ask you. I hope these won't be just my problems with this calculation and other people that would like to get into part translation in the future will find your explanation for their (and my) problems here too.

Hey Sylvain! I love your how-to! It took me a couple of days to get my head around the quaternions but now I think I understand them a little bit. I even accomplished a full correct translation using your tutorial. Though there sill ar a couple things I don't get... maybe I'm just a little bit slow with maths. I was wondering how do you get √2/2 (which is 1) from this: cos(a/2) = sin(a/2) = cos(π/4) = sin(π/4) = √2/2? And than how you get this: cos(π/2) = 0, sin(π/2) = 1? Because by typing it into my calculator I get something completely different... And lastly do you build your quaternion off of this form: q = cos(a/2) + sin(a/2).(ax.i + ay.j + az.k)? And if yes what happens with the rest of the factors? (I feel that all this questions have a really simple answer and I'm just being dumb, but as I said I've been trying to get my head around this for a couple days now and I need to finally know!) But other than that, as I said, I was able to use your examples and calculation to translate a part without any problems and I think that it would be very easy for everybody alse that has this problem with the translation. It's just me that would like to understand how it works. With regards, Theodor.

I just realized it isn't perfect either... :(

Well you sure got me excited for the how to now, (regarding the fact that I only understood half of what you tried to explain there) but until than, very quick question: are you doing the translation inside LeoCAD or how are you using it oder the for previewing the changes you made in the ldraw.xml file? As for LDraw part accuracy: have you seen this website called http://www.mecabricks.com? All their parts were modeled by measuring the IRL parts. I did here the same thing you did for comparison:

Thank you for fixing 2561! The thing that would be interesting, maybe not only to me but also for other users that want to help out, is how you calculate the right translation for complicated pieces like the 2561? I think it would help out a lot with keeping this file up to date if someone could put a short tutorial together and post it here. As for the 2562: it looks to me as if the LDraw model isn't acurate. Could that be? With regards, Theodor

The right lines for the lego Batarang: <!-- Boomerang Wing 55707c.dat--> <Brick ldraw="55707c.dat" lego="98721" /> <Transformation ldraw="55707c.dat" tx="0" ty="0" tz="0" ax="1" ay="0" az="0" angle="1.570796"/> instead of: <!-- Minifig Utensil Batman Bat a Rang two wings with handgrip bar in middle 98721 35a --> <Transformation ldraw="98721.dat" tx="0" ty="0" tz="0" ax="0" ay="1" az="0" angle="3.141593"/> Corrected: <!-- 97782 35a --> <Transformation ldraw="97782.dat" tx="0" ty="-0.24" tz="0" ax="0" ay="1" az="0" angle="3.141593"/> <!-- 95054 35a --> <Transformation ldraw="95054.dat" tx="0" ty="-0.44" tz="0" ax="0" ay="1" az="0" angle="-1.570796"/> <!-- Minifig Weapon Hand Dagger 88812 35a --> <Transformation ldraw="88812.dat" tx="0" ty="0" tz="0" ax="0" ay="1" az="0" angle="1.570796"/> <!-- Minifig, Weapon Bladed Claw 88811 35a --> <Transformation ldraw="88811.dat" tx="0" ty="0" tz="0" ax="0" ay="1" az="0" angle="1.570796"/> I also discovered that 2562 and 2561 are really broken, but I can't fix them with my current knowledge. If someone could take a look at that or teach me how to fix them I would be grateful. Theodor