Problem Extruding an Editable Spline

[tmccarter]

Hey everyone,

 

I'm creating high-rise storefront window frames using an editable spline that consists of a series of closed splines nested within a larger closed spline. I extrude the whole thing and voila; I have a frame with many crossmembers and openings. This works great 90% of the time (as long as my vertices are welded and my splines are all closed off). But sometimes - even if I follow all the rules - I get a result like the screenshot I've attached. Now get this; I fix it by moving some of the vertices slightly. Usually, I make sure all the vertices have the same x or y values so that my frames are all perfectly parallel, but the only way I've found to fix this weird behavior is to move one or two of them around on the x or y axis so the lines are less than parallel. Any idea why the heck this happens? What am I doing wrong?

 

Thanks

 

-Tim

[Virgil Johnson]

Tim,

 

Is it that the faces are missing or are the normals wrong?

 

I had run into this problem for the first time a couple of days ago with some L shaped sidewalks.

The faces were missing in some corners.

 

I did the same fix as you and got it mended but since I had to finish for a deadline I never got to figure out what was going wrong either.

 

Virgil

[tmccarter]

It seems like some faces are missing form the end caps, but the normals might be weird, too. I tried all sorts of modifiers on the object (edit poly, edit normals, subdivide, you name it) nothing seemd to change the overall problem. I tried changing the vertex order of the splines, reversing, refining, all sorts of stuff. Very strange thing, you move one vertex a few undredths of an inch and it goes away. Oh, well. A question for the ages I s'pose.

[Horhe]

Hmm i think it might be a problem with the verticies handles (the two handles with square helper modifiers at the ends). Try and selecting those verticies and scalling them down somewhat.

[Virgil Johnson]

I have printed the suggestion and put it my big book.

 

Next time I have the problem I will try the scale-the-vertices option.

 

Virgil

[tmccarter]

Jakub,

 

Thanks for the reply. That's a good idea. In this case I converted all the vertices to "Corner" types so there are no bezier handles, and I still got the weird missing faces.

 

-Tim

[Horhe]

In that case the problem lies within the splines that are imported from cad. Try deleting and replacing the verticies and areas of the spline that are causing this with the ones from max.

It may be a problem with the import options ticked at the begining.

[Michael Emo]

I've run into that problem before. It happens to me when I have a wall, whereby the window/door opening is really close to the edge of the wall.

 

Then I extrude and one corner will get whacked out, even though everything is welded and all the correct plane. I usually just move the vertices, but would like also to know how to prevent this from happening in the future.

[Koper]

so the object consists of many different splines and the problem you are having is that each of the first vertexes don't correlate. when a cap is being put on it tries to match all the vertex numbers and thats why there seems to be holes or missing faces

 

so display the vertex numbers in the sub-object vertex mode, then look at were the number 1 vertex is for each spline, then just select the most top right vertex of each spline, right click and select 'make first

 

 

 

tell me when you guys don't understand and i'll give a couple of screen grabs

[beestee]

I know I have read a more current thread on this somewhere, but I cannot seem to find it. The fix that came up in that particular discussion was to mess with the spline steps and turn off 'optimize' and 'adaptive'. Well, I ran into the issue and started searching for a different solution because I tried the method above to no avail. I also tried the ones here that I could, and none of them worked with this particular spline with the exception of moving the points a little, which is a far from elegant solution.

 

I decided to dig deeper and found that using the Bevel modifier rather than Extrude solves the issue. Just use the 'Level 1 Height' as your extrude amount, and turn on 'Start' and 'End' capping. I even tried to make the problem spline worse to try to produce the error again but the Bevel modifier just plugged away faultlessly with each effort to stump it. The calculation did slow down as the number of instances were increased within the outer spline, but it did work after giving it enough time to compute. Anyways, hope this method helps somebody else avoid and/or solve this problem in the future.

 

Also in my tests, I found that it is the uniform face alignment that causes the problems. You can create a very large number of abstract shapes within an outer spline and extrude has no problem as long as there aren't a bunch of them perfectly aligned...oddly enough, it even handles that situation amazingly fast on the cpu.

[Peter M. Gruhn]

Thanks for the tip. I know I'll run into the issue again someday.

[beestee]

I was able to make a mess of it again while using the bevel, although the tolerance was better. Just chalk Bevel up as another possible solution, but not the be all end all solution I thought it was. For the mesh I needed I was able to use sweep since I was doing a ceiling grid (uniform width), but that method will not work for a lot of scenarios. I fear it is an inherent problem with the way Max builds faces when using morph type capping...perhaps it is something that will be addressed with XBR eventually.

[Hernav41]

Help me....

 

I have a problem, when I try import from CAD file to 3ds max ( i make a spline from corel, and export to dwg file), the spline I extrude and then I convert to polyline. but when I make a boolean , it's no success...

 

this screen shoot:

 

 

problem is the lines in (a) object, use remove edge, not succes too.

 

Tq before.....

[Peter M. Gruhn]

You might get better results by making the outer and inner shapes parts of the same spline object (use attach) before extruding and not use boolean at all.