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Sweeps not working as expected
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December 13, 2009, 12:10:28 PM
How does one use the sweep commands for real-world objects?  Every time I try to use the commands on my path I get an error message about self-intersecting objects.

What's up with this?  First of all "Rail Sweep" works improperly EVERY time.  It simply cannot orient my profile the way I want -- and there are no tool options to fix this.  Yes, I have put the ref point where I want it, and I oriented it (painfully) normal to the path -- even though it says you don't need to.

Then I tried the regular sweep -- by using the swept shape positioned normally to the path.  I got the SAME self-intersecting error message; then no sweep.  Of what good are these tools if they are so limited?  Must my applications all be exactly like those in the help docs?

My application is to Create a small parabolic profile to (hopefully) sweep along a path of text.  Of COURSE there are going to be intersections.  I have no problems overlapping solids in other areas of TC.  Why would TC15.2 complain about this?

Is there something I've missed, or are these features used so seldomly that no one uses them and therefore bugs are not fixed?  Here is my file.

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* December 13, 2009, 03:00:33 PM
#1
You could try this with the "Rigid Sweep" option for the Sweep tool, but it doesn't come out looking all that great. Other have had better success than I with this tool.

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John R.

V17—V21, 2015—2019
Designer, Deluxe, (Professional, Expert, Basic), Platinum
RedSDK enabled
Windows 10 Pro (1903), 64-bit


* December 13, 2009, 03:34:28 PM
#2
How does one use the sweep commands for real-world objects?  Every time I try to use the commands on my path I get an error message about self-intersecting objects.

What's up with this?  First of all "Rail Sweep" works improperly EVERY time.  It simply cannot orient my profile the way I want -- and there are no tool options to fix this.  Yes, I have put the ref point where I want it, and I oriented it (painfully) normal to the path -- even though it says you don't need to.

Then I tried the regular sweep -- by using the swept shape positioned normally to the path.  I got the SAME self-intersecting error message; then no sweep.  Of what good are these tools if they are so limited?  Must my applications all be exactly like those in the help docs?

My application is to Create a small parabolic profile to (hopefully) sweep along a path of text.  Of COURSE there are going to be intersections.  I have no problems overlapping solids in other areas of TC.  Why would TC15.2 complain about this?

Is there something I've missed, or are these features used so seldomly that no one uses them and therefore bugs are not fixed?  Here is my file.

Use Rail Sweep. After activating the tool, click the Properties icon on the IBar and in the 3D page, set Create 3D Object As to "TC Surface." (Genie doesn't mind if "Surface" objects self-intersect.) Then go to TC Surface Options (still in the Properties dialog) and set Number of Approximation Lines to about 60. Also click the "Smooth" option.

Henry H

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« Last Edit: December 13, 2009, 03:36:00 PM by Henry Hubich »

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December 13, 2009, 05:43:19 PM
#3
Henry:

Thanks so much for your in-depth knowledge of TC.  Doing as you suggested works to create the object as a surface.  Now, even if I separate one of the surfaces so as to be non-intersecting graphics, and explode it twice to get a TC Surface, the Format Command to Create a Solid from a Surface is always ghosted.

Is there any way to convert this surface into a solid?

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* December 13, 2009, 06:06:13 PM
#4
Henry:

Now, even if I separate one of the surfaces so as to be non-intersecting graphics, and explode it twice to get a TC Surface, the Format Command to Create a Solid from a Surface is always ghosted.

Is there any way to convert this surface into a solid?

Genie is confused by her own terminology in this case. A Surface in Format|Create  Solid from Surface means an empty zero-thickness shell; i.e., a sheet object. That is not at all the same thing as a "TC Surface." Therefore the command is not applicable, since the drawing doesn't contain any sheet objects.

Converting TC Surfaces into Solids requires either opening the Properties|3Ddialog and checking "Solid," or checking the "Solid" box in the 3D field of the Selection Info palette. BUT you still cannot convert a selfintersecting object to a Solid. The vertical stroke of the B in "Ball" is a non-selfintersecting object, so it CAN be converted. The remainder of the B can be converted if it is first sliced into two pieces, after which each piece is made into a Solid (and the pieces Boolean added back together if you wish). The rest of "Ball" is pretty complex and I'm not at all sure it's feasible to slice-and-dice and then convert.

Henry H
« Last Edit: December 13, 2009, 06:08:09 PM by Henry Hubich »

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December 13, 2009, 08:14:25 PM
#5
Thanks again Henry.  I was thinking it might be simpler use the Drawing commands (Or use Offset on the original Paths) to get a 2D version of the text.  Then Extrude it to height.  Then use the 3D Fillet Edges for a rounder shape.

Do you see any problems this way?  (I do lose my profile, but it's better than the alternatives.)

Nope.  That does not work either.  I can get the Offsets to make letter outlines.  Extrude will do those, but again, it's not a solid.  If I try to use Format to make a surface, then Extrude will not extrude it.  Who designed this program?  Santa's elves?

Is there any alternative?  Something is missing here!
« Last Edit: December 13, 2009, 09:01:02 PM by t.karlmann@comcast.net »

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December 14, 2009, 04:50:08 AM
#6
I was thinking it might be simpler use the Drawing commands (Or use Offset on the original Paths) to get a 2D version of the text.  Then Extrude it to height.  Then use the 3D Fillet Edges for a rounder shape.

Do you see any problems this way?  (I do lose my profile, but it's better than the alternatives.)

Nope.  That does not work either.  I can get the Offsets to make letter outlines.  Extrude will do those, but again, it's not a solid.

You may have to create a Region using your whole outline, then try to extrude again.  Or extrude the outer parts, then the inner parts (make the inner parts stick out at the top and bottom more than they need to), then 3D subtract the inner parts.

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Josh T.
meatballrocketry.com
TC Pro 18.2 & Platinum 2016


December 14, 2009, 09:25:41 AM
#7

You may have to create a Region using your whole outline, then try to extrude again.  Or extrude the outer parts, then the inner parts (make the inner parts stick out at the top and bottom more than they need to), then 3D subtract the inner parts.

You cannot extrude a region!  Well, mine will not allow this.

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* December 14, 2009, 09:54:18 AM
#8

Is there any alternative?  Something is missing here!

Why not leave the Rail Sweeps as TC Surfaces, as shown in the attachment to my original reply?

Henry H

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December 14, 2009, 02:41:17 PM
#9
You cannot extrude a region!  Well, mine will not allow this.

I just extruded a region in v 11.2.   I don't know if this has changed in v 16.


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Josh T.
meatballrocketry.com
TC Pro 18.2 & Platinum 2016


December 14, 2009, 03:24:19 PM
#10
You cannot extrude a region!  Well, mine will not allow this.

I just extruded a region in v 11.2.   I don't know if this has changed in v 16.



Am I stuck again with the version (mine = 15.2) that can't do anything?  V11.2 and v16.x are the ONLY versions I do not have.  It seems like v11 does everything -- this is not the 1st time I've run into this v11 thing.  After v11 everything fell apart?

Henry:  I cannot use surfaces -- I need a solid.
« Last Edit: December 14, 2009, 03:47:37 PM by t.karlmann@comcast.net »

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December 14, 2009, 03:44:26 PM
#11
Here is what I did:  (Translation: this is just too much work and workarounds for something that should be simple)

Why Did I do all this?  Because TC's Rail sweep does not work as it says it does.

Follow along and try not to ZZZZzzzzzzzzz.
1) take the original path, use offset on both sides to get a "fat" path.
2) Close the ends with the Edit tool.
3) Use the split entity tool to break the beziers where they cross.  Oops, must explode into ploylines first.  Why?  Dunno apparently TC can't have anything that intersects itself. 
4) Must zoom in almost to the limits because TC isn't smart enough to go beyond one polyline segment to split it.
4a) Delete the intersecting segments.
5) No go back to each intersection, even though we used snaps all the way, and use Meet 2 Lines to get everything together, sort of.
6) Now select each piece and use the Join command to really get it back together.
7) Now we have one polyline.  Great, now use convert to curve and we get to play around with the numerical tolerance in Properties to get the corners.  Why? Because TC is too stupid to recognize corners of a curve on its own.
8) I'm sure I forgot some steps.
9) Now we can extrude the shape -- after selecting all the parts.
10) Lest I forget -- now trying to add contour to the shape?  Forget it becuase you must select EACH polyline segment OF THE EXPLODED ACIS solid in order to get some shape.  I lost it there.

Sketchup or Solidworks anyone?
Thom
« Last Edit: December 14, 2009, 03:51:00 PM by t.karlmann@comcast.net »

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* December 14, 2009, 08:09:11 PM
#12
Sweep them as surfaces as Henry suggests, then explode them twice to TC surface, then change them to solids in properties, then format them as solid from surface.

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* December 14, 2009, 09:28:09 PM
#13
Sweep them as surfaces as Henry suggests, then explode them twice to TC surface, then change them to solids in properties, then format them as solid from surface.

Yup, that works. Can't convert the sweep directly to a Solid, but conversion after two explosions does the trick. Wouldn't have thought it ;-)

Henry H

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December 15, 2009, 09:53:54 PM
#14
Working!  After initially telling Rail Sweep to use surfaces, then exploding the result twice, selecting the surface, then using properties to convert to a solid is working.

Some issues remain.  The first time I did this, the swept object was a polyline.  The conversion to a solid took maybe 5 minutes to convert.  I then redid the entire process after converting the swept shape to a Bezier.  Much faster.  Much smaller file size -- went from 43M to ~5m.

However, I was playing with the parameters of the Rail Sweep.  My latest result looks very odd.  Its almost as if just the node points of the bezier were swept, then connected together linearly -- the bezier curve itself apears to not have been swept.

What's the best way to do this -- minimize file size and get the right shape?

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* December 15, 2009, 11:59:39 PM
#15
That's right.  A TC surface is a facet object which approximates the curvature in the same way that a polyline approximates a curve.  Although you've converted the surface into a solid, the faceting remains.  Two ways of improving things:  You'll see that the profile at the joined segments is normal to the path.  You can use that join to align copies of your profile and loft along the path, at least for those parts of the path that don't cause selfintersection.  Use the surface methodology for the trickier bits.  If you choose to use the surface methodology for the entire object, cutting the path up improves the resolution, ie the number of approximation lines is distributed over a shorter length of the path, giving a smoother result, in the same way that increasing the number of polyline segments between control points makes an exploded curve look smoother.

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December 16, 2009, 04:32:58 AM
#16
Here's a thought I just had.  Someone may have addressed it, and I missed it, but here goes:

Is is possible to break up each letter into multiple parts and do shorter individual rail sweeps that do not intersect themselves but do intersect the whole (but wouldn't be a problem since the paths have been separated)?

Then you could 3D Add the parts together.  Sorry if I'm repeating something already addressed.

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Josh T.
meatballrocketry.com
TC Pro 18.2 & Platinum 2016


December 16, 2009, 12:41:08 PM
#17
That's right.  A TC surface is a facet object which approximates the curvature in the same way that a polyline approximates a curve.  Although you've converted the surface into a solid, the faceting remains.  Two ways of improving things:  You'll see that the profile at the joined segments is normal to the path.  You can use that join to align copies of your profile and loft along the path, at least for those parts of the path that don't cause selfintersection.  Use the surface methodology for the trickier bits.  If you choose to use the surface methodology for the entire object, cutting the path up improves the resolution, ie the number of approximation lines is distributed over a shorter length of the path, giving a smoother result, in the same way that increasing the number of polyline segments between control points makes an exploded curve look smoother.

I'm not sure I have communicated my present difficulty accurately.  In your quote above, I think you were referrring to the path.  However, when I mentioned my concern over my results, I was referring to the geometry of the object swept along the path.  I will attempt to take some illutrative screen shots...

In the attached photo, you can clearly see that the sweeping profile is a bezier, yet the rail-swept shape seems to lose all the cuvature of the profile and linearly connects some segments of the profile for the not-smooth result.

So, again, is there a way to minimize file size and still get the shape I want?
I know I can convert the little profile to a polyline, but the file size -- just for this logo gets to be over 43Mbytes, and consequently very difficult to manage, light, move, etc.

AHA!!!!  Just had a real MOMENT here!!!!  It's NOT the rail sweep of the surface that's making the faceted shape, it's the conversion to solid that causes the undeirable faceting!  What to do?

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« Last Edit: December 16, 2009, 01:22:37 PM by t.karlmann@comcast.net »

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* December 16, 2009, 03:57:20 PM
#18
It's sweeping as a surface that causes faceting.  That's why there's an approximation line number in the properties dialogue.  The higher the number, the more segments and better apparent smoothness.  Henry mentioned slicing and dicing the sweep.  What he meant by that is cutting the parts of the path that cause selfintersection out.  The remainder can be swept as solid, inherently smooth.  

Josh, the point of sweep is continuity along the path.  Segmenting it and sweeping solids will have poor continuity in the areas of selfintersection.  

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« Last Edit: December 16, 2009, 04:08:16 PM by murray dickinson »

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* December 16, 2009, 04:11:59 PM
#19
AHA!!!!  Just had a real MOMENT here!!!!  It's NOT the rail sweep of the surface that's making the faceted shape, it's the conversion to solid that causes the undeirable faceting!  What to do?

Are you sure you can't leave it as a Surface?

Henry H

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* December 16, 2009, 05:17:17 PM
#20
What to do?

Try to find a copy of TCad v11.2 Pro. That version featured a tool called Normal Extrude, with an option to select a path for the extrusion. After I converted your Beziers  to Polylines, that version had no trouble creating the Ball logo as Solids. (The artifiact at the tail of the second "l" in the logo disappears when the drawing is rendered.)

Henry H

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December 16, 2009, 06:56:59 PM
#21
It's sweeping as a surface that causes faceting.    

Mine is not working that way.  I set the rail sweep to 25 and checked Smooth.  I got a real nice shape.  See picture #1

Then, I exploded twice, converted to a solid -- THEN I got the faceting.

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December 16, 2009, 06:58:35 PM
#22
AHA!!!!  Just had a real MOMENT here!!!!  It's NOT the rail sweep of the surface that's making the faceted shape, it's the conversion to solid that causes the undeirable faceting!  What to do?

Are you sure you can't leave it as a Surface?

Henry H

Absolutely Certain -- I have other solids this needs to be added to.  First warped.

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December 16, 2009, 07:06:07 PM
#23
What to do?

Try to find a copy of TCad v11.2 Pro. That version featured a tool called Normal Extrude, with an option to select a path for the extrusion. After I converted your Beziers  to Polylines, that version had no trouble creating the Ball logo as Solids. (The artifiact at the tail of the second "l" in the logo disappears when the drawing is rendered.)

Henry H

I have tried to get v11 in the past -- when I was stuck with v10.5 -- I was told it was unavailable.  So I ended up with V14 -- yup when all the new stuff was described in another version, I was left with very little info on how all the changes worked.  Now I have v15.2  Yes, I know TC has gone down the drain after v11.  After all, who needs the parametric constaints if they are not on and done automatically all the time???

I refuse to spend any more $$$ on TC until I am CERTAIN that a lot of things have been fixed -- not just adding some new door option!!!

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* December 16, 2009, 07:31:43 PM
#24
smoothing is cosmetic, a rendering effect that improves the appearance of facet surfaces and meshes.  Refer to the last line of the help entry for mesh and TC surface properties
 
« Last Edit: December 16, 2009, 07:51:04 PM by murray dickinson »

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* December 16, 2009, 08:07:39 PM
#25

I have tried to get v11 in the past -- when I was stuck with v10.5 -- I was told it was unavailable.  So I ended up with V14 -- yup when all the new stuff was described in another version, I was left with very little info on how all the changes worked.  Now I have v15.2  Yes, I know TC has gone down the drain after v11.  After all, who needs the parametric constaints if they are not on and done automatically all the time???

I refuse to spend any more $$$ on TC until I am CERTAIN that a lot of things have been fixed -- not just adding some new door option!!!

If you still have v10.5, you're home free. See attached screenshot. Normal Extrude was better in some respects in v10 than in v11.

Henry H

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December 17, 2009, 11:41:05 PM
#26
smoothing is cosmetic, a rendering effect that improves the appearance of facet surfaces and meshes.  Refer to the last line of the help entry for mesh and TC surface properties
 

The last line in Help for Properties when a TC surface is selected says: "Style: A group of properties defined for a group of tools. See Styles".

Can you be slightly more specific?

???

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* December 18, 2009, 02:37:19 PM
#27
The help pages.  Smoothness is illusory.  Convert to a solid, the appearance differs, the geometry is unchanged.

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« Last Edit: December 18, 2009, 02:44:58 PM by murray dickinson »

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