Sweep Object in Cheetah3D Manual

#1
Probably stupid question, but how do you produce the U tube as shown in the Cheetah3D Manual for the Sweep Object. Using the Sweep Object with the two circle splines as profile and path, as described, I just get a closed Torus. I’ve tried varying every property of all 3 entities, but to no avail,,, even Boolien interaction with a cube and/or plane to get the cut off ends, but to no avail — help
 

ZooHead

Well-known member
#3
This is another method. Using an n-edge instead of a circle you can better control poly count.
You can also change the approximation angle on the spline.
SweepTubeAlt.jpg
 
#5
Martin has taken the image from an ancient version for the help file which is incorrect unfortunately:
View attachment 34533
Cheers
Frank


AH!!!!!!! That explains it - I immediately saw that the spline objects were editable. Oh for a history file, so that you can see the steps used.

I had a look at the Javascript of SweepTube.jas, but this seems to give only the finished state.

I will update my saved/printed/bound copies of the Manual.

If there are any other important (everything is important to a learner) out of date/wrong, parts of the Manual, I would be very grateful if you could let me know, so I can update.
IMG_3909.jpg
IMG_3908.jpg
 

Helmut

Well-known member
#9
* Not sure what you are after, but a tube + a bend modifier also works for a simple U-tube.
* Probably better for engineering / plumbing bits.
* For modelling bovine intestines (see cow manure and bull :poop: in a related thread) you need sweeps, anyway.
Screenshot 2019-08-15 at 14.20.36.png
 
#11
* Not sure what you are after, but a tube + a bend modifier also works for a simple U-tube.
* Probably better for engineering / plumbing bits.
* For modelling bovine intestines (see cow manure and bull :poop: in a related thread) you need sweeps, anyway. View attachment 34546
Hi,

Helmut,

thank you for your learned input, but I posted initially, coz I was thinking that I had missed something in the Manual, ie I followed the given steps and just got a torus. Frank has now enlightened me that "Martin has taken the image from an ancient version for the help file which is incorrect unfortunately:". If I had started long ago, with Cheetah3D with said 'ancient version', I would probably not be so flummoxed.

In passing, I think that I would give someone a wide berth, if I learned that he/she was interested in 'cow manure and bull:poop:', let alone modelling it!!!
 
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#12
A kind of follow on about spline use:

I am trying to construct the Mug in Tonio Loewald’s excellent book and have come to a stop at the ‘bridge’ step, since the ‘spline/handle’ does not seem to be a polygon object. I cannot select a bridging point at either end.

I have a Youtube video:


where at 2:48 he also uses the ‘bridge’ tool to construct a ‘handle’ but here he bridges between two polygon extrusions.

The final Mug as shown in Tonio’s 'mug-final.jas’, shows the n-Edge as not editable, whereas the books instructions say it has to be editable.

What am I missing.
 

Attachments

Helmut

Well-known member
#14
@SOF
* A quick intro to SWEEPS
* Elements in the object browser::
1 the Sweep creator at the top level of the hierarchy
2 the cross-section at child node 1
3 the axis at child node 2
* Basically, a sweep is a tube of any profile / cross-section following any path / axis. Both cross-section and path need to be splines (from simple linear to Bezier to NURBS).

* It is a very useful and powerful tool once you can "think" in splines. Working with splines is neither subtractive nor additive modelling (as, basically, is box modelling) but primarily conceptual fiddling.
* There is the added advantage of twisting and scaling using the parameters. Of course, sweeps can also be parental nodes of modifiers.
* You can use various clusters of sweeps (arrays, rings, particle meshes) if required.
* There are also a number of scripts which can be deployed in conjunction with splines.

Screenshot 2019-08-22 at 11.26.39.png
Screenshot 2019-08-22 at 11.27.03.png
Screenshot 2019-08-22 at 11.27.17.png
Screenshot 2019-08-22 at 11.27.36.png
Screenshot 2019-08-22 at 11.27.56.png
 

Attachments

#15
@SOF
* A quick intro to SWEEPS
* Elements in the object browser::
1 the Sweep creator at the top level of the hierarchy
2 the cross-section at child node 1
3 the axis at child node 2
* Basically, a sweep is a tube of any profile / cross-section following any path / axis. Both cross-section and path need to be splines (from simple linear to Bezier to NURBS).

* It is a very useful and powerful tool once you can "think" in splines. Working with splines is neither subtractive nor additive modelling (as, basically, is box modelling) but primarily conceptual fiddling.
* There is the added advantage of twisting and scaling using the parameters. Of course, sweeps can also be parental nodes of modifiers.
* You can use various clusters of sweeps (arrays, rings, particle meshes) if required.
* There are also a number of scripts which can be deployed in conjunction with splines.

View attachment 34579 View attachment 34580 View attachment 34581 View attachment 34582 View attachment 34583
Fantastic Helmut, I have already had a lot of fun making various exhaust tubes (Mufflers if your USA!) with splines, but your examples will keep me happy and busy for days/weeks to come... Unfortunately I do not have all the scripts needed eg 'spline grid.js in my resource, only Sinecircle, Bounce and Round...angular. Is there a source or do I search in the scripting forum section.?

Thanks again, I am becoming more and more impressed with Cheetah and all you dedicated and VERY clever helpers.
 
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Helmut

Well-known member
#16
* @SOF
* On my Mac, I have organised C3D .js scripts partly in additional subfolders to achieve some logical organisation. I have also renamed a few of the .js scripts. As a result, C3D on your macOS won´t find the path for a link.
* However, the Java script for 2D / 3D grids (courtesy of Master Hiroto) should be available in the C3D section for scripts for a download.
 
#17
* @SOF
* On my Mac, I have organised C3D .js scripts partly in additional subfolders to achieve some logical organisation. I have also renamed a few of the .js scripts. As a result, C3D on your macOS won´t find the path for a link.
* However, the Java script for 2D / 3D grids (courtesy of Master Hiroto) should be available in the C3D section for scripts for a download.
Thanks Helmut,
I have already found the missing js's and copied/renamed spline grid ( in your jas, you refer to it as spline grid in one line and Grid Spline in another) I cannot load Splines 5.jas as I get a javascript error: and the rotating ball of death shows up!!
js error.png
 

Helmut

Well-known member
#18
* @SOF
* Splines 5 contains the Java scripts PathedHelix.js and a second one which draws a loxodrome (which basically is a spiral on a sphere between N-pole and S-pole). This I fumbled together years ago when I needed it for a long forgotten purpose :unsure:

* Re PathedHelix.js:
* Looks like I use a later version from 2010 and the older version is from 2007. A comment in the code 2010 says that the .js was edited by Frank in that year.
* I guess there is an old link in the master list which needs to be corrected by somebody with suitable privileges.

Screenshot 2019-08-23 at 14.17.37.png


:oops: An interesting script for tubular constructs is SplineWrap.js.
* Parental object = Java script SplineWrap.js
* child node #1: any spline as the axis of the tubular construct
* child node #2: any mesh which will be distorted to "flow" along the spline
* The mesh on node 2 needs a suitably fine geometry so it can be distorted along the axial sopline.

* I stuck the Java scripts in the archive attached.

Screenshot 2019-08-23 at 14.37.57.png
 

Attachments

#19
* @SOF
* Splines 5 contains the Java scripts PathedHelix.js and a second one which draws a loxodrome (which basically is a spiral on a sphere between N-pole and S-pole). This I fumbled together years ago when I needed it for a long forgotten purpose :unsure:

* Re PathedHelix.js:
* Looks like I use a later version from 2010 and the older version is from 2007. A comment in the code 2010 says that the .js was edited by Frank in that year.
* I guess there is an old link in the master list which needs to be corrected by somebody with suitable privileges.

View attachment 34607

:oops: An interesting script for tubular constructs is SplineWrap.js.
* Parental object = Java script SplineWrap.js
* child node #1: any spline as the axis of the tubular construct
* child node #2: any mesh which will be distorted to "flow" along the spline
* The mesh on node 2 needs a suitably fine geometry so it can be distorted along the axial sopline.

* I stuck the Java scripts in the archive attached.

View attachment 34604
Thanks for your persevering with me. This Forum is such a revelation. Most that I have visited, including the one I was a moderator in, have a cadre of experts who are so much up their own fundaments that cries for help from the less intellectually endowed are cast aside - you and your friends are wonderful, as is the never tiring Doc Martin.

Robert
 

Helmut

Well-known member
#20
* @SOF
* I think that this has little to do with intellect. It is just acquired trickery. Experience takes time, be it 3D modelling, playing the piano, cooking or heart surgery.
* Maybe, the cognitive skills of spatial imagination play some part in the initial creative deployment of 3D but that seems to be just an aspect of education, as well.

* Only recently and by chance I read some interesting analyses on the fluctuations of human IQ (it has - albeit mildly - increased over many decades; it now seems to decrease over the last few years). The studies (US, Italy and Finland) seem to conclude that educational TV (Sesame Street was mentioned in the US tests) did increase IQs and social skills whilst kIds who who watched cable TV and commercial soaps showed a gradually reduced metric in such skills.
* Assuming such studies can be verified (the mentioned article was little more than a synopsis), I conclude that curiousity, an open mind and perseverance in a challenging task is paramount. Occasional frustration is good fun once you experiment and mix "eye of newt and toe of frog" to the standard C3D martini.
 
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