Subject:
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Re: (First post) enter position and rotation dialog
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Newsgroups:
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lugnet.cad.mlcad
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Date:
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Thu, 29 Jul 2004 11:35:41 GMT
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Viewed:
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6115 times
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In lugnet.cad.mlcad, Jeremy Vandivere wrote:
> Hi everyone,
> I just started getting interested in lego modeling in MLcad, and I am
> really enjoying it. I am having a little trouble with it though..maybe
> you can help me out...
>
> I have placed a part (plate 1x2) into the work area, and I need to
> rotate it along the X axis. in the 'enter position and rotation' dialog,
> it says the angle is already 90 degrees. this is referring the the 90
> degrees I had to rotate it to get it pointed long ways instead of
> sideways. (can you tell I'm new?)
>
> Basically a breakdown/tutorial of the enter position & rotation dialog
> would be greatly helpful. Does anyone know where I might find such a thing?
>
> Thanks for your help!
> --Jeremy
>
> PS: playing with this program has prompted me to buy my first real lego
> set in years. Anyone know when spider-man parts will be added to the
> parts list? :)
What you're trying to do is define a rotation vector, which can also be
explained as a "custom-oriented axis". Its origin is always 0,0,0 and it will
extend in the direction set by the XYZ coordinates.
This way of working is very powerful, meaning it can take very few actions to
achieve complex rotations. But it can get tricky to figure out all the maths
(rotation matrices are even more extreme in both counts).
One thing that you can try is unchecking the "Absolute" (values) checkbox at the
bottom of the dialog. That will enable you to do it step by step.
For instance, in your case it seems like you have the following XYZ value to
define the rotation vector (0,1,0) and 90 as the rotation angle.
So that is a 90-degree rotation across a custom axis that passes 0,0,0 and 0,1,0
(yep, that "custom axis" is in the same palce that the Y axis).
Now, uncheck "absolute". set the rotation vector values to 1,0,0 and type in the
angle that you want for the roof slopes rotation. That will rotate them in the x
axis.
Note: I don't remember and I can't look into this right now, but the whole 0,0,0
origin might mean that you have to place your parts in the world origin (0,0,0)
to perform the rotation and then move them backl to where they belong.
I hope this helps. In the book "Lego Software Powertools", we included an
illustrated description of this and the rotation matrices process. Also, the
POVray help file includes a very short but good description of rotation
matrices.
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Message is in Reply To:
 | | (First post) enter position and rotation dialog
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| Hi everyone, I just started getting interested in lego modeling in MLcad, and I am really enjoying it. I am having a little trouble with it though..maybe you can help me out... I have placed a part (plate 1x2) into the work area, and I need to (...) (20 years ago, 27-Jul-04, to lugnet.cad.mlcad)
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