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DrStrik9
07-21-2009, 07:57 PM
I'm doing a very repetitive modeling project, where I start with a spline in a bkg layer, create two points in a foreground layer, hit p to make a 2-point-poly that is oriented at a 90-degree angle to the bkg rail, and then control-R for rail extrude. Every point of both the bkg rail and the foreground 2-pt poly is on 0 on the Z azis. It's a super-simple set-up.

Unfortunately, about half the time, rail extrude fails to work properly, and instead of getting a nicely shaped ribbon of polys, I get a single line of points, as if my originating 2-pt-poly was only a couple of points already aligned with the bkg rail. :-( I typically solve this error by manually constructing the "ribbon of polys" I need along the rail, using extend, move, and rotate. This takes several minutes, where if the rail extrude would actually WORK, it would be instantaneous.

When I encounter the error, I've merged points, aligned polys, flipped both the foreground and background items, and anything I can possibly think of to solve it when it fails, but without success. Once rail extrude fail, it fails on that set-up thereafter.

What else could the problem be? Does anyone else have this intermittent weirdness with rail extrude? Is this possibly a bug, or just something stupid I'm doing or not doing?

Thanks for any help ...

cagey5
07-22-2009, 03:59 AM
Strange. It works every time here.

DrStrik9
07-22-2009, 11:44 AM
I've even killed the bkg rail and created it again, with the same points, but the result of the rail extrude is still wonky.

Really, it makes no sense.

I've decided to include a .lwo of one of the 2-layer setups that always fails as a rail extrude here. Maybe someone can tell me what stupid little thing I missing or doing wrong ...

My Rail Extrude settings are:
Uniform Knots
50
Oriented

Thanks for any help.

cagey5
07-22-2009, 11:48 AM
If I turn the 2 point poly through 90 degrees on the x axis it extrudes fine

DrStrik9
07-22-2009, 11:55 AM
If I turn the 2 point poly through 90 degrees on the x axis it extrudes fine

That would be great if I wanted it at 90-degrees on the X-axis, but I need it right where it is ... otherwise the rail extrusion is useless to me.

If you attempt to rail extrude it as it is when you open the model, what happens? And are you on a Mac or PC?

Thanks ...

cagey5
07-22-2009, 12:05 PM
PC. And as set, the 2 point poly twists, to effectively align itself with the rail as it extrudes.

Sekhar
07-22-2009, 12:09 PM
Yeah, it's messed up for me as well, on 64 bit/Vista. Basically, starts off fine and immediately collapses into a line.

Try this. Copy an end point of the curve to another layer and convert it to a 1-point poly. RE that with your settings, and you'll get a 2-point poly chain. Extrude that to get your ribbon.

I've given up on RE because it's so finicky and use methods like this instead (and the wonderful LWCAD for making rods and stuff).

DrStrik9
07-22-2009, 12:12 PM
PC. And as set, the 2 point poly twists, to effectively align itself with the rail as it extrudes.

Crap. That's what it does here too, on Mac. So it's either something with the model itself (which is most likely) or it's a bug (not very likely). I just wish I could figure out how to fix it. I've tried everything I can think of ...

I need the ribbon of polys to have all its points at 0 on the Z axis, and I need a consistent oriented ribbon width, following the bkg spline. It just seems ridiculous to have to build it by hand when Rail Extrude is MADE for this situation ...

Thanks for looking at this with me. If you find the answer, I'll be overjoyed (that is, if you share it with me.) :-)

cagey5
07-22-2009, 12:17 PM
Have you tried turning 'oriented' off on the rail extrude panel?


Having said that it gives you another problem of course... hmmm

DrStrik9
07-22-2009, 12:17 PM
Yeah, it's messed up for me as well, on 64 bit/Vista. Basically, starts off fine and immediately collapses into a line.

Try this. Copy an end point of the curve to another layer and convert it to a 1-point poly. RE that with your settings, and you'll get a 2-point poly chain. Extrude that to get your ribbon.

I've given up on RE because it's so finicky and use methods like this instead (and the wonderful LWCAD for making rods and stuff).

Thanks for trying this also. It really helps to have other minds puzzling with me. :-)

If I understand your 2-pt poly chain idea, when I extrude the final result, it won't be oriented with the original bkg rail, and I'll have to move 100+ points by hand. (Did I understand correctly?) If so, I might as well build the entire ribbon from the original 2-pt poly, with the bkg rail as a visual guide, using extrude, move, and rotate.

DrStrik9
07-22-2009, 12:22 PM
Have you tried turning 'oriented' off on the rail extrude panel?

That works fine. When it's done, I have to rotate each ribbon cross-edge to orient them manually with the rail, but at least that's faster than what I was doing before. And it has the added advantage of Rail Extrude's sensitivity to rail-point proximity.

I guess that's the workaround. THANKS.

I think I'll report this on FogBugz. Maybe they can tell me why it doesn't work as it should.

cagey5
07-22-2009, 12:24 PM
ok. Last attempt. Before you rail extrude rotate your 2 pt poly so it is in line with your rail then when it twists on extruding it twists to give the orientation you are looking for (apart from the first few points but they are relatively easy to straighten.

[i.e. rotate 90 on the z axis]

Sekhar
07-22-2009, 12:26 PM
Thanks for trying this also. It really helps to have other minds puzzling with me. :-)

If I understand your 2-pt poly chain idea, when I extrude the final result, it won't be oriented with the original bkg rail, and I'll have to move 100+ points by hand. (Did I understand correctly?) If so, I might as well build the entire ribbon from the original 2-pt poly, with the bkg rail as a visual guide, using extrude, move, and rotate.

No, it'll be already aligned. Make sure the point you select corresponds to the beginning of the curve. Below is an example I created for you. Your curve is in layer 1 - follow the progression in layers 2 (1 point poly), 3 (RE'd to make a 2-point poly chain), and 4 (extruded to make a ribbon).

DrStrik9
07-22-2009, 12:31 PM
cagey5:

Dang! That is brilliant. You should write a book on how to outsmart temperamental software! LOL

When you see the results, it makes perfect sense. What's happening is Rail Extrude is (wrongly) rotating the 2-pt poly 90-degrees toward the rail direction on its first extrusion. Your last idea basically UN-rotates it back, so only the FIRST section is wrong. 95% of the Rail Extrusion is as it should be. SUPER easy to fix. LOL

You get the GOLD STAR today, sir. :-D

DrStrik9
07-22-2009, 12:36 PM
No, it'll be already aligned. Make sure the point you select corresponds to the beginning of the curve. Below is an example I created for you. Your curve is in layer 1 - follow the progression in layers 2 (1 point poly), 3 (RE'd to make a 2-point poly chain), and 4 (extruded to make a ribbon).

OK, I wasn't clear in the beginning it seems. I need the RE to look like the attached jpg (oriented 90-degrees from your example). And cagey5 gave me the ideal workaround. Sorry for not being clearer to begin with.

3D is harder to describe with words (at least for me) than it should be. :-)

Sekhar
07-22-2009, 12:38 PM
Cool, the important thing is you have a workaround. :)

DrStrik9
07-22-2009, 12:40 PM
Cool, the important thing is you have a workaround. :)

You guys rock, seriously.