Parabola object (need help)

I originally wrote a plugin to (a) create screw threads and (b) to learn Ruby. It’s kinda mutated from there in the last five years. Every time I would need something that the native SketchUp tools wouldn’t do easily (or couldn’t do at all), I would add it to my code. Somewhere along the line, I started documentation, but it’s still a work in progress. When I joined the forums a few months ago, I was toying with the idea of modifying it to work in the Extensions library, but I’ve decided to leave it as a plugin for now. There’s a big difference between fiddling around with code and making it professional. There is also the licensing issues that may or may not arise … my plugins come with no strings attached. While I wrote this for my own use, it always gives me a warm fuzzy when someone else uses it to solve some weird shape. On occasion, the inability of the plugin to do something will spawn a whole new layer of options. If you’re not already familiar with the Spirix website, here’s the URL: spirixcode

And, of course, if anyone chooses to use it and has questions, I’ll be more than happy to try and help them figure it out.

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Awesome. Marvelous. Thank you.

Makes me feel foolish for even attempting to do this stuff by hand. Well, not entirely. After all, people knit, yodel, and breed guppies for a hobby. I suppose I can draw a few shapes without apology. Still, you know.


I spoke too soon, and I misread the desired shape. Follow Me won’t work, but jimhami42’s method is awesome.

Since the subject of this thread is “Parabola object” …

I created a true parabola with 74 points and used it to regenerate my previous surface:

Interesting shape, but probably not quite what was originally requested:

Billions of blistering barnacles! Is it really so? This must be a forum for anachronisms!


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Mr jimhami42 the only i have to say is at least it is perfect!This is what i want.With just a few clicks , but i can not manage even those few clicks.Let’s suppose i would like to connect those two objects , where is the problem now?

I see you’ve already discovered the WTF function :wink:

I see several problems … but start with something simple first:

  1. Start a new model and set the units to decimal inches
  2. Create an arc using 30 edges (make sure it’s several inches tall)
  3. Use the Spirix “Create Group” option to name it “1”

  1. Create another arc using 30 points, stretch it, and then use “Create Group” to name it “2”:

Note the placement and orientation of the arcs:

Click “OK”:

When morphing one contour into another, the two profiles must have the same number of points in order to map one curve to the other. Any geometry that is used for a Spirix contour must be created in linear order (head-to-tail). Using the native SketchUp Group option will (not so) arbitrarily reorder the elements and break the continuity. Using the Spirix “Create Group” will preserve this order.

When I created the rectangular outline, I created the grid I showed and grouped it. Then I “traced” 18 lines from grid point to grid point until I reached the first arc; then I created the 6 sided arc continuing the same direction and added 26 more edges until I reached the second arc; created the arc using 6 sides and continued on around the corner adding 18 more lines. When I was done, I used the “Create Group” option to create the Spirix contour. Sounds tedious, but it took less time to do it than to tell about it.

When I created the semicircle, I used 74 sides, stretched it, and then grouped it using the Spirix “Create Group” option. By default, Spirix will revolve the geometry around the (vertical) Z-axis. All geometry is assumed to be in the +X/Z plane unless told otherwise.

A note about the Spirix “Create Group” … the Group function grabs anything in your model that is not in a group and uses it to create the group. You must make sure that everything else is grouped so it will not interfere with the “Create Group” option.

See if this helps … the documentation for this is very poor and it is good to get feedback on how to explain this better,

BTW, the contours must start and end in similar directions … if you get them backwards, Spirix will cheerfully create what you asked for:

I manage it with two curves line , the wrong i did was that one curve was opposite direction.

But with one curve and one rectangular , things are harder. I have set all as you told , what is wrong? I suppose something wrong with rectangular . I have name those contour through Spirix create group

Untitled.skp (230.1 KB)

It looks like you’re closer now than before. I count 28 edges along the right side of the rectangle, not 29. I grouped everything you have already and then traced around the outside of your rectangular geometry using 10 points on the arcs and 18, 28, and 18 along the edges. I named this “A”. I then created a parabola with 84 (not 85) edges and named it “B”. Then it worked like it should. I’m not sure if you’ve read this, but it might help clear things up a little more for you (the example uses the extrusion function, but the creation of the groups will be the same): spirixcode - G - Morphing

BTW, it’s not clear if you’re trying to make the inner and outer surfaces in one go or not … while you can do this, it’s a little more complicated, so I would stick with making one and then the other.

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I’ll be a monkey climbing on a caephalopod! I stay away for a couple of days and this thread turns into geopoetry in motion! Pats on the back all around!

Take a look at the curve maker plugin.
It has the option to easily draw a parabola. It is symmetric about the radial axis so very easy to draw a revolution by the follow me tool. Attached is a simple concept I was using as an investigation of making model for you. However I am use to using one with F/d ~ 0.3, front fed or cassegrain

with vertex matching plate in that case. You have not presented enough detail that any thing I try will not be useful to you, so I decided before proceeding in never land hopefully you can give some additional insight on use and real size so I am not wasting time.
To make the transition form the parabola to the structure consider the use of TIGs extrude tool. Unlike the follow me it is some what adaptive which is a big plus in my mind.

Hi mac7595, i really thank you for your help,it is very useful and needs meditation. I will come back in a few days because these days i am on examination for university and i have not ime :neutral_face:

Good luck on you test;
I have been assuming your post is indicative of a head lite design, so I looked at my 4 Runner. It looks close to yours with notable difference. FYI; It is a focal point off set design probably used for beam steering to help account for the curved front end; It has a specially designed bulb in what I call a cup to help with illumination ; More importantly the front lens is flat to avoid any ray distortion.
Take a look at cars around you if I am close it means all the effort by those above are for naught if I am and reason for you to have good definition of what you are trying to do. :smiling_imp:

Attached is pic of head lite. It follows contour of front grill, the bulb/ cup is shown and the reflector contour

Here is link you may find interesting.

Hi mac7595,I come back , it was something easier from head lite designer. I would like to make just a case to place inside a small tablet for my car.I should have mention it from the beginning ,it was my fault.
Spirix plugin from jimhami42 is really usefull for curving things !

more photos here

And one more question,all those lines seems all over the case could be a way to be hidden??Of course i could sand it more, but is there any way not to be printed at all??

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Those lines are the actual sketchup lines. As far as I know the printers usually prints Sketchup models as you would see them without the smooth.
Use more triangles in your geometry/more segments in your arcs. Or try using a subdivide/smoothing plugin like artisan.
Maybe the segments should be just a little shorter than your printing resolution.