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Aligning an Axis and Reference Rotate


Jeff Mottle
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Hey MAX gurus,

 

I am rebuilding a model in MAX using surface tools from splines that I have imported from Rhino. (File was originally from PRO/E)

 

In setting up all of my splines to ensure I create 3 and 4 sided boundaries I have run into several instances where I have needed to mirror splines about another line as well as align a line/spline to another line and finally be able to "Rotate Reference" (like in AutoCAD).

 

The problems I am running into are as follows:

 

1. I know that in order to mirror a spline I can use the "pick" option from the Reference Coordinate box to choose the object I need to use as the mirror axis. My problem is that lines do not have a rotation, so the axis is never aligned to it. The guy I work with was able to figure out an ingenious way to get axis to line up properly, but am wondering if there is another way that I have missed. His method was to snap a bone to the endpoints of the line and align to the bone. To mirror the line he just parented the line to the bone. I suppose the same would work with any object, but that brings up another problem (see #3)

 

2. From a group of attached splines, is there a way to mirror a single spline from within that group? Even in Spline sub-object mode the entire group of attached lines wants to mirror. Is this a limitation of MAX?

 

3. How do you align an object to another object by rotating it around a fixed point? If you have used AutoCAD this is equivalent to rotating with the reference option. Yo can move and use snaps, but there seems to be no way to rotate an object around one point and snap to a second point. Any ideas?

 

If none of this has made any sense, I'll try again. Hopefully somebody can figure this one out.

 

Thanks,

Jeff

 

[ October 07, 2002, 04:13 PM: Message edited by: Jeff Mottle ]

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I may be missing your idea/question completely, but when I need to duplicate and mirror splines (or anything for that matter) I've always been able to get it done by translating and rotating the object's pivot point to wherever I needed the "reference" point to be. The mirror or clone action I'd then perform would be using If this "point" were an exact point along another spline, I guess you could copy that point's coordinates into the pivot point's transform type-in. You might already know everything I'm saying here, and I apologize if I didn't understand the question completely. Most of this response would be in reference to your first question. If you could give a more specific example of the third, I might be able to help. As for question #2, I guess you could go into sub-object mode, select the desired spline, detach it as a copy, deselect the original group of attached splines, select then mirror the one you just detached , then select your group and re-attach it. I personally prefer to do spline modeling in Rhino - it has all the precision, reference points, and translation methods a cad program has (more from what I can tell) for drawing, and the surfacing tools are much more intuitive than max's. Anyway, I hope I understood you and some of this helps.

 

Ken Walton

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Originally posted by Ken Walton:

I may be missing your idea/question completely, but when I need to duplicate and mirror splines (or anything for that matter) I've always been able to get it done by translating and rotating the object's pivot point to wherever I needed the "reference" point to be.

Hey Ken,

 

Yeah I understand how to get the pivot point to the location I want, but tell me how I get the X axis for example to align perfectly with the line. This works no problem with geometry that has a third dimension, but does not work with lines or splines. Try it. This is why we found that snapping a bone to the endpoints would help.

 

For #3. Picture a sraight line and a box that is not aligned with that line. Now if I snap one of the corners to the line's endpoint my goal would be to snap the other box corner to the other line endpoint so that it was aligned with the line. See the attached picture.

 

This is the start point:

 

filepush.asp?file=notalign.jpg

 

This is what I want, but I want to be able to snap the rotation.

 

filepush.asp?file=align.jpg

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Jeff,

 

I wrote a little script for such things. It aligns an object to a spline. It doesn't snap to one point but thats where the move tool comes in ;) .. Just move it with snap on.

 

The script is on my website, or my test-site.. The test-site is my new "going to be" site

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You da man! Quizzy

 

Originally posted by quizzy:

Jeff,

 

I wrote a little script for such things. It aligns an object to a spline. It doesn't snap to one point but thats where the move tool comes in ;) .. Just move it with snap on.

 

The script is on my website, or my test-site.. The test-site is my new "going to be" site

 

[ October 08, 2002, 07:56 AM: Message edited by: Jeff Mottle ]

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Be aware though, its in alpha stage, so no error handling thusfar. But it works, you'll find out about what you can and can not do... have fun...

 

BTW: I wrote this script because it is not possible in MAX and it was one of my favorite "tools" in AutoCAD, rotate->reference

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OK just to continue this topic. Is there a way to precisly orient the rotation of a pivot point of a vertex? Lets say I have a few vertices on a line, but the line is not parallel with an axis. Is there a way to slide the vertices along the existing line segment or at the very least be able to orient the pivot point preceidely so that I can slide the vertex? make sense?

 

Jeff

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Hey Quizzy,

 

Ok for example I am buildng spline cages for surface modeling with surface tools on some fairly organic parts. To get the spline relatively straight around the entire object I want to be able to shift the vertices to achive this. In the image below you can see the start of the part I am modeling and a line that I drew to illustrate my point. The coordiantes are set to local, but as you can see if I wanted to shift a vertex down the line I would have to move in both the X and Y direction and I would then lose the nice straight line I had. This gets furthur complicated when the lines are more complex like the example in the background. Make sense? I can obviously change the pivot point for the entire object, but not an individual line or line segment in a group of attached splines. A bit of an aside but mirroring falls into this same cateory and is very difficult to do when you can not precisely set up the axis with a definite line.

 

Hopefully I have explained this better?

 

filepush.asp?file=sample.jpg

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Looks like you already have the answer to your first question, but what I usually do when I want to align things to splines is to make a tape object and snap the start and end of the tape to two pints on the spline, then I align the object to the tape which is oriented the right way. But that script may be handy too.

 

Oh... just to add to this... you may know this, but a highly underused aspect of splines is the reverse direction tool under the edit spline menu.

 

[ October 16, 2002, 11:13 AM: Message edited by: Christopher Nichols ]

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okay i get it now jeff,

 

Well try to imagine this: the vertice can be a corner, bezier, smooth or bezier corner vertice right? Well how can it be possible to shift a vertice then. It's not, I think. You would like to shift the vertice along spline or move along spline. What would happen if the vertice had for instance a bezier corner ... you'll get some pretty wierd things i think. There must be some plugins for this i think and its not possible in MAX (I'm not sure). You can still use the refine button or maybe the normalize spline modifier..

 

But tell me what your goal is or what you want to achieve with this... Why do you want more vertices, to get more control to get a higher polygon count etc etc.....

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So I can get edgeloops that are more or less straight all around the object. Makes for nice geometry. I hate seeing skewed meshes. I can do it manually, but it just takes longer...much longer.

 

But tell me what your goal is or what you want to achieve with this... Why do you want more vertices, to get more control to get a higher..

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