General Question Vector & Rotation Points?

[Saturn V]

Hi guys,

Anybody know how to set the correct vector & rotation points in a situation like this...

I need to get the rotation points along the red vector line so the door rotates properly (green arrow), but the "hinge" along the bottom of the door remains along the vector line.

The image above is about as close as I've been able to get it which is...passable I suppose, but could be better (not to mention more accurate). Going cross-eyed since yesterday changing values bit by bit!

Any help much appreciated...

Thanks

 

[Quick_Nick]

Don't use trial and error, use Mesh Wizard.

 

[Saturn V]

Tried that Nick. Actually used that in conjunction with Pablo's VectorNormalizer. As I said, the end result of that and "trial & error" is the image above.

That's what I'm getting at...I must be either not understanding something, or even worse, understanding it WRONG!

The calculator function in MeshWizard which is supposed to help figure the rotation points and vector for the rotation is seriously confusing me. Believe me, I'm trying to grasp the concepts, but I'm not having much luck. I'm okay with building/modifying the model meshes, but I'm a total noob at making them actually DO something.

---------- Post added at 04:08 PM ---------- Previous post was at 12:26 PM ----------

I believe what I'm not understanding is obtaining the DIR and ROT coordinates for the ROT vector. The door certainly rotates smoothly. Even got it to function like a retractable bomb-bay door...slid very neatly into the Gemini hull. Unfortunately, that's not what I'm after...

So, how do I correct the error?

 

[liber]

Ask a Donamy at PM,he animated mine A380,he's expert with that.

 

[Saturn V]

Yes, I know he is. He's already given me a great deal of help & information with the robotic arm set up for the recovery chopper. That's why I feel like a putz asking him for more help. Though now that you mention it, he did do the original Gemini models. Hmmm...the door does open for EVA. You might have something there liber!

 

[ar81]

[ame="http://www.orbithangar.com/searchid.php?ID=3178"]Tutorial: Vectors for dummies[/ame]

[ame="http://www.orbithangar.com/searchid.php?ID=3429"]Vector normalizer tool[/ame]

 

[Zatnikitelman]

What I'd do to grab the unusual vector of this door is to go into MeshWizard and view one plane. Get perhaps the Y-Z coordinates at one end, then the other. Then go into top view and get the X-coordinates. Get the difference between the X, Y, and Z values and plug those into MeshWizard's vector normalizer. Depending on how accurate you got with the points, the only guessing and checking should be which value to put the negative sign in front of. The point about which it rotates can just be one of the two points you got earlier. I've found that as long as your rotation point lays on the axis of rotation, you should be fine. If you really want to however, you can make it the midpoint of the axis.

 

[Quick_Nick]

If needed, I'd be more than happy to help out if you gave me the msh and ini. More than likely though, you'll get this sorted out before needing my help.

 

[Saturn V]

Thanks guys. Pablo, I already read your tutorial and though it helps me to understand the concept, I'm getting hung up on how to practically apply that to this model. Sort of like the difference between reading a cookbook and cooking, know what I mean?

Zat, the proceedure you outlined is precisely what I've been attempting most of the past 2 days. I've gotten close, but still "no cigar," as they say :suicide:.

 

[Donamy]

I use AC3D, it gives the vector of 2 vetices, and stores them in memory, then it's just paste into the .ini

Port
pos= -0.838,0.427,0.087
vector=0.293596,-0.142293,0.94528

Stbd
pos=0.828,0.426,0.087
vector=0.292789,0.143753,-0.945309

 

[tblaxland]

I use AC3D...

Hmm: http://www.orbiter-forum.com/search...1&s=&query=AC3D&searchuser=Donamy&showposts=1
You've got this on your business card, right?

 

[ar81]

To get the 3D coordinate for EACH point, click the point in 2 different views in Mesh Wizard.
Then use vector normalizer.
Second point is where vector points.

For example, click on point A in side view, then change to let's say rear view and click the same point A in that view. You may get the 3D coordinates for point A. Copy the coordinates to vector normalizer.

For point B do the same.

Once you have the coordinates of two points, use vector normalizer to calculate the vector.

Points A and B may be anywhere along the line of the desired vector. That way you may use either A or B as rotation point.

 

[Donamy]

Hmm: http://www.orbiter-forum.com/search...1&s=&query=AC3D&searchuser=Donamy&showposts=1
You've got this on your business card, right?

I'm just trying to help people, enjoy making Orbiter addons easier, that's all.

 

[Saturn V]

Pablo,

Thanks for the explaination. Below are the results I got based on your instructions.

I believe the vector is correct...at least based on the image at the far left. The door will rotate completely around the circumference of the spacecraft, and it does follow the compound curvature of the hull.

However, I am not sure that it is correct, or that my rotation point is correct based on the center and right pictures...

I can not seem to get the door to rotate in the proper direction if anything I ve done is correct.

And if nothing is correct, then I have no idea what I'm doing wrong.

I really do have to look into AC3D. But if I'm having this much trouble with basic stuff, you'd have to send out a search party for me as soon as I installed it.:sos:

 

[Quick_Nick]

It's look like your rotation point is way off. I'd really like to help, but I'm not sure what more I can say that others haven't. I can however try to do it for you though.
All you really need is the rotation point. The rotation value/axis should be fairly simple, since it's rotating around a basic axis. (I'm assuming you are using SC3, but if not it shouldn't be too different)

 

[Saturn V]

That's what I'm getting at. According to Pablo's directions, I should be able to use point A or B as the rotation points, which I did, and this is the result. For the life of me, I just don't know where I'm screwing it up.

 

[Donamy]

did you use the coords I posted ?

 

[Saturn V]

Hi Donamy,

Yes I did. Well, I tried anyway, but getting pretty much the same result.

Which figures should go into the ROT PNT and what goes into ROT AXIS?

 

[Donamy]

pos= rotation point

vector= Rotation axis

It should work, unless you've changed the position of the mesh in your 3D program. If you want to send me the mesh you are using, I can do the animations for you in about 10 min.

 

[Saturn V]

Yes, that's what I did. Still getting the rotation around the circumference of the spacecraft instead of a rotation away from it.

Looking at the mesh, it doesn't appear that the Gemini mesh itself has been moved (just added to), BUT, I'm using the higher detail gem_capsule_dom mesh as opposed to the basic gem_capsule mesh particularly because of the inner-door detail. Don't know if this is part of the problem.

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