Lofting problem...

[mzagorski]

Im trying to loft a shape in Viz to make some seams on a sheet metal roof but its not working as expected.

 

I made my shapes in Autocad, do a Boolean -> Loft -> Pick Path (or Pick Object) It lofts along my path but changes the orientation.. see attached image.

 

 

What is the correct way to do this?

[Ted Boardman]

>> made my shapes in Autocad, do a Boolean -> Loft -> Pick Path (or Pick Object) It lofts along my path but changes the orientation.. see attached image

 

Mike,

 

Position your path where you want it, use Get Shape and hold the CTRL key when you pick the shape to flip it 180deg on the path.

 

Check out my CGarchitect columns from last Jun/July for the principles behind the orientation of shapes in lofting.

 

Ted

[mzagorski]

Hi Ted,

 

Well... I read your 3 lofting tutorials before and after trying to loft this simple shape but still cant get it to work.

 

I ended up tracing my imported autocad path in max which fixed on problem, but now the loft is rotated 90 degrees further than I need it to be:

 

 

I cant see how I can fix this. I am surprised that such a popular 3d program such as viz/max fails to badly on simple modelling tasks such as this...

[abicalho]

Mike,

 

When you do a Get Path, it will use the Shape's orientation and build the object from there. That's why it's building the other direction.

 

You should select the Path, click Loft and then use Get Shape.

 

Now, the shape could also be misoriented, and that you can adjust by either applying an Edit Spline to it and rotating, or by going into Sub-Object Shape in Loft and changing the orientation there.

 

It's not that the program doesn't work the way you want, it's just that there's no easy way to guess how Imported geometry should look like. In your case, the normal of the shape points on the other direction; or, when doing a Get Shape, the rotation of the shape is also flipped cause it was created in a different UCS and orientation in AutoCAD.

 

Hope it helps,

 

Alexander

[Ted Boardman]

>>I ended up tracing my imported autocad path in max which fixed on problem, but now the loft is rotated 90 degrees further than I need it to be:

 

Ah ha, always mention that the info was imported, that can play an important part.

 

What I think is happening to confuse you is that the shapes were created in Acad in something other than the WCS. I'll bet if you Extrude your shapes there will be issues, too.

 

Try this:

 

1) create a shape in VIZ and convert to Editable Spline.

 

2) Attach the imported shape to it.

 

3) At sub-object Spline, select and detach the VIZ spline.

 

4) Go to Hierarchy, Affect Pivot Only and Center to Object or position the Pivot where you want it to be on the path.

 

5) Now try the loft.

 

As Alex says, it is almost always easier to place the path and use Get Shape.

 

See, it's Acad's fault it doesn't work right!

 

Ted

[Ted Boardman]

>>always mention that the info was imported

 

Oops, sorry Mike, you did mention that in the message. My miss.

 

Ted

[mzagorski]

No problem Ted - revolved going back into its holster

[mzagorski]

Still cant get it to work. ALl created in WCS in Autocad 2000. If anyone wants to have a go at lofting this semmingly simple item then you can download the file here

[Ted Boardman]

>>Still cant get it to work. ALl created in WCS in Autocad 2000. If anyone wants to have a go at lofting this semmingly simple item

 

Mike,

 

It worked fine once I attached to a shape I create in the Front viewport and then detached the original in max 4. Should be exactly the same in VIZ.

 

Without attach/detach the shape just makes a ribbon on the roof path because it's local Z axis is wrong from Acad.

 

Ted

[mzagorski]

Thanks Ted! :angecool:

[Ted Boardman]

>>Thanks Ted!

 

Mike,

 

Do you know what time it is?

 

Let me know if it works for you. It's a very handy thing to know about because it crops up in imported shapes alot.

 

Ted

[vizwhiz]

hi There

 

Mike

 

check This out (i Think it works)

 

1. the shape you were trying to extrude only had 3 lines, i added the 4th segment and did a pedit "close" (actually i re-created the pline with the ucs set current for the object)

 

2. did the extrude path

3. voila presto gizmo !

 

now i am sending an upload of the finished item

i tend to model in autocad what i can only think of in VIZ,

 

 

i am always so impressed when Ted and Alexander explain how VIZ actually works

because i never will have the level of understanding that they do

 

(professionally jealous)

 

Thanks

 

Randy

[nisus]

Hey guys,

 

From the example I've seen, I wonder why you people loft anyway. I could be mistaken upon mike's goal, but lofting a simple rectangle to a path is crazy like hell imho.

 

I'd draw the spline in a front view, edit spline/outline it and add an extrude/bevel modifier. It's a simple as this with perfect control upon polygon count.

 

Remember the best trick is to think 180degrees from what you know Don't do the obvious, think GOAL! héhé

 

There is one reason why one should loft though: mapping along the path. Most other lofts could be done in a much simpler way imho!

 

rgds

 

nisus

[mzagorski]

Nisus - to show what this loft was for - I'll attach an image of my WIP. Look familiar? LOL

 

I was making the ridges for the roof..

 

 

I reached my end goal by just modelling it in autocad, creating copies of my block the import that into Viz. Far less trouble for a cad orientated monkey like myself