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View Full Version : Rail extrude, it never ever works



Geoff Vane
12-13-2007, 07:02 AM
I can't take it any longer. If it's not coughing up twisted and distorted nonsense, it just won't work at all.
Multi spline extrude works when I just create some crap splines, but with the actual good ones it doesn't work. It's good I don't live near the Lightwave programmers...

http://img153.imageshack.us/img153/5826/railextrudeproblemcm0.jpg

cagey5
12-13-2007, 07:13 AM
replied in other thread.

StormRising
12-15-2007, 04:23 AM
You need to use just one spline for the rail. Make that spline the center of your pipe. Then place a disc polygon the diameter you want the pipe to be at the start (the diamond end) of your spline in another layer. Now shadow the spline layer. And select rail extrude, tweak options, and hit ok. Should work.,:thumbsup:

cagey5
12-15-2007, 04:25 AM
One is fine if you want an even tube type effect, but a second can be used to give a modified outline as above, and should work just as well, so that is not the cause of the problem.

StormRising
12-15-2007, 04:30 AM
see..

cagey5
12-15-2007, 04:32 AM
I'm not sure what that shows other than it works fine with one spline which is nothing to do with the original posters query.

StormRising
12-15-2007, 05:58 PM
It shows how to make a pipe out of a spline. I thought thats what he wanted.

Anyway, you help him. lol

gerry_g
12-16-2007, 02:22 PM
I can't get it to work either, correction I wouldn't even bother trying to get it to work, thats why I use several modelers, some are better at somethings than others, LW is very good at many things, but not this

gatz
12-16-2007, 02:30 PM
Pictrix C Worm would be perfect for this type of operation. You can sculpt curve and scale the profile to create beautiful shapes. Downside: It's yet another plugin and its not prodeural so keep your curves and profiles around for tweaking.

rg

Roly
12-16-2007, 04:09 PM
It's working for me.

gerry_g
12-16-2007, 05:17 PM
Actually I tried it again cos I had a nagging doupt that I had used it in the past and it worked fine ( albeit in a very Lightwave sort of way), when I tried it yesterday it screwed up totally, the splines I used were made from points that had been cloned from solid geometry that had been beveled to create two matching paths and I thought this might have been the problem.
When I retried today it worked just fine every time, so either check your splines/paths make sure they are snapped to the profile, even try a restart to see if modeler hasn't become corrupted.

THREEL
12-16-2007, 09:09 PM
Check out the double post a little lower that Geoff started on this same subject. There are some interesting posts about Rail Extrude there as well.

meshpig
12-17-2007, 02:55 AM
Sometimes with rail extrude and rail clone, the settings need to be rechecked each time you back-track depending on how badly you have set it up.

-Both of them work fine if you aren't pi**ed or being a lazy, unthinking blob; ie. stop and rethink the settings each time.

Those tools are dysfunctional usually because you are trying to fit too much geometry into the equation and haven't thought it through.



m

meshpig
12-17-2007, 03:20 AM
Actually I tried it again cos I had a nagging doupt that I had used it in the past and it worked fine ( albeit in a very Lightwave sort of way), when I tried it yesterday it screwed up totally, the splines I used were made from points that had been cloned from solid geometry that had been beveled to create two matching paths and I thought this might have been the problem.
When I retried today it worked just fine every time, so either check your splines/paths make sure they are snapped to the profile, even try a restart to see if modeler hasn't become corrupted.


Yeah, you can see how the splines still aren't quite right for the impending geometry.

Have you seen Proton's tutorial array yet?

http://www.newtek.com/forums/showthread.php?t=77002

m:)

meshpig
12-17-2007, 03:37 AM
It shows how to make a pipe out of a spline. I thought thats what he wanted.

Anyway, you help him. lol


I agree, what use 2 when 1 isn't helping. Besides, the second is only a modifier.

m:)

gerry_g
12-17-2007, 04:32 AM
I agree, what use 2 when 1 isn't helping. Besides, the second is only a modifier.
I think the point is that two spline sweeps done in other packages work as advertised and the control the second spline offers is of real use, I don't like to dis LW but some of its tools really could do with updating

meshpig
12-17-2007, 05:42 AM
I think the point is that two spline sweeps done in other packages work as advertised and the control the second spline offers is of real use, I don't like to dis LW but some of its tools really could do with updating


Maybe, but I don't really buy that in context.

m

gerry_g
12-17-2007, 06:22 AM
So to do this first time right of the bat with no screw ups wouldn't help him out hu

BeeVee
12-17-2007, 07:04 AM
Use one spline to guide the path of the hexagon and the other to determine how width of the pipe. The first spline should be centred, the other shows the scale of the pipe. In the picture attached the first spline is right up the middle of the hexagon, the second free-standing one determines the scale of the pipe.

A couple of notes:

* Make sure the normal of the polygon to be extruded is as close as possible to extending the original spline
* Try to keep things as close to the origin as possible to avoid rounding errors.

B

meshpig
12-18-2007, 12:26 AM
So to do this first time right of the bat with no screw ups wouldn't help him out hu


No, I agree it would help.

-Are you talking about the tools or the method though? The original error message; "can't establish valid basis ..." is a matter of method; the splines aren't in the right place.

All I was saying is it would be easier to sort it out using 1. Obviously it doesn't present a problem for you.

M:)

gerry_g
12-18-2007, 06:17 PM
Thank you BeeVee for your explanation it all makes perfect sense now, I'm used to modelers that have a more consistent approach to spline modeling, LW though good sometimes requires you to weld splines as in patching other times to snap or use the centre point/pivot (even though it has no native centre snapping tool), and added to this most sweeping is done with interpolated splines, which I hate as they're absolutely useless most of the time, you only have to go watch Protons paper clip tutorial video (the link is in one of the above posts) to see why he recommends arraying the curves over using splines as his spline modeled version is totally lame.

BeeVee
12-19-2007, 02:12 AM
The advantage of having a central spline is that you can have multiple guides to dictate scale of the extrude meaning you can have a python lying on the ground that is swallowing a deer by having one guide straight and another on the other side all lumpy (if you see what I mean).

B

gerry_g
12-19-2007, 05:05 AM
Well a Gordon surface will sweep using multiple splines and a couple of profiles, there's nothing new there I think it's just a question of consistency of methodology.