Good morning all,

I would like to know how some of the more experienced moi users on here would generate this simple shape stepping shape from the top to bottom portion of this mesh is what i am after.

Its a type of shape i generate a lot in traditional polygon model apps quite often and was wondering if there is a solution in moi that is fairly quick and repeatable?
I tried yesterday using lofts and boolean but with little success , any help is appreciated.

Cheers

Matt

model joined

if it's what you want .. i'll post tip

can be more rounder probably

i begin with an half circle but any initial draw is possible

Hi Corchet,

Wonderfull ,that is exactly what i would like to achieve , thank you so much.

Could you post your process please ?


Thanks again


Matt

A proposition...


Use lofting straight with red and orange curves.
Use sweep with orange and green profiles using cyan rail.

Next you can mirror and close your model using black lines if you want have solid.

You use filetted curves profiles before loft and sweep.






Perhaps a simplier solution exists...

with fillets

Could you post your process please ?

i drink a coffee and i post that ;)

Brilliant !

Thankyou so much.

Cheers.

Matt

draw profil and rebuild ( press tab in the blue area write Rebuild .... in the right corner of the screen : press Done )

the rebuild is good to eliminate parasite lines when extrude etc .. )

extrude the profil ... copy the solid and apply scale ( here in the bounding box i wrote 1.2 ) ( 120 percents bigger )

draw a polyline and apply fillet ( this line will cut the 2 solids )

cut the 2 solids ... boolean diff



place the solids where you want ( verify the vertical alignement )

draw a small profil ... it will join the 2 solids all around ( if you draw rounds parts on this profil ... fillet and rebuild it )

transform ... mirror this small profil

transform ... orient ... line to line allow to copy this profile between 2 points, lines etc ...

if you don't know this command refer to moi doc ... it's a very cool function

i copy ( with line to line ) the profile between the 2 solids ( when nyou use that ... it says End .. End to help you in the position of the copies



the first piece is a sweep between 2 rails

the others are networks ( all between 4 borders ) if borders are spliited you need to join the segments













the good way for a network ( 4 borders )







the surfaces created ( sweep and networks are surfaces )

if you want a solid at the end of the job you need to delete faces on the 2 solids ( in brown on the pictures )

check grid snap and object snap and glue the surfaces

select all faces of the final piece and join them ... it's solid

there is other ways to do that ... this one with line to line allow various shapes between 2 volumes

3dm file

Hey Corchet,

This is even better solution than the curves for me , im going to try both now !
Thanks for the transform orient tool tip , will look into this too.

I have been a poly/subdiv modeler for years , moving into this realm as its much quicker but still have some habits to break , this is a real help !

Thanks again for sharing your knowledge , really appreciate it.

Matt

sweep one rail with any profiles

the same thing with all rebuild lines

the break on the surface disappear ... it's cleaner

you'r welcome ;)

rebuild on lines

3dm file

Hi Matt, there are some tips here for people coming from a poly modeling background, they may be helpful:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

NURBS modeling is usually at its best when you build things primarily from 2D profile curves and you initially focus on simple blocky extended shapes, what you might call an "underlying form". You don't want to directly draw in the 3D non-planar boundaries to these underlying forms, you want them to be created by the result of a boolean that carves off pieces.

So let's focus on one area's underlying form here:



If you temporarily ignore how it ends at the top, the basic extended underlying form for that part of the model is like this:



Then to get it to end how you want, draw in a profile curve in the Front view like this:



Select the main block, run boolean difference and discard the upper piece:





Ok, now let's focus on the underlying form for another area. Temporarily ignore the transition areas between the major forms.

So for this upper area you can do a similar process:



Construct > Offset can be good for making a curve that is an even spacing away from an existing one:





Side profiles:


Boolean difference:


Discard excess pieces:



So note now that to get to this spot we've only used 5 2D curves, there were these 2 in the Top view:


And these 3 in the Front view:


That is pretty much the key thing that you want to be shooting for to leverage the most out of NURBS modeling and to make things happen fast. You want to make large pieces of your model from a small number of 2D profile curves with some generating shapes and some cutting way material.

Ok, so now for the transition, I would go about this by deleting these faces:





Then set up the select naked edges script on the N key (http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2)
so you can select all these with one keypress:


Use Edit > Join to glue them together into 2 closed curves, then you can select those closed curves and do just one loft like this:


Then select the 3 pieces and use Edit > Join to glue them together and make a solid.

It would be good to clean up the side - delete these faces:


Select the main object and run Construct > Planar to seal off the end with one planar surface. It's better for filleting to have single large planes for things like this and not several coplanar separate fragments:



Then select these edges:


And fillet:






Hope this helps!

- Michael

Hi Matt, so it is also possible to do the whole shape in one loft using the Loft style = "Straight" option.

To do it this way you would set up curves like this, cutting them at these lines with the Edit > Trim command so there are some curve segment ends there that you can move later. You want all the curves to have the same number of segments for this method:


Then you arrange them vertically like so, using Ctrl+drag twice to drag off a copy:


Turn on control points for the middle ones and drag these points downwards:





Then you can select all the curves and run Construct > Loft, using the Loft style = "Straight" option to make this result:


This is however a lesser quality result than the method above, you can see that there is more fragmentation in it. Filleting in particular will not like how the coplanar areas are fragmented in multiple pieces. You can fix it by deleting those coplanar areas and then using Construct > Planar to fill in new larger planes:






I would encourage you though to approach things more like the other method I posted method where you're thinking more about building extended pieces where possible and cutting them rather than trying to shape things in 3D directly from the start. That's what takes some getting used to when coming from a poly modeling background.

The extended base shape + boolean cut method also helps in more general situations like if you have some curved shape instead of lines:




That then becomes better and better to be driving things by 2D curves rather than trying to pull some large number of control points around in 3D.

- Michael

<< Then set up the select naked edges script on the N key (http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2)
so you can select all these with one keypress:

<< Use Edit> Join to glue them together into 2 closed curves, then you can select those closed curves and do just one loft like this:

When you say "Join to glue them together into 2 closed curves" it's the 2 family's curves Joined in the same time
or Join family curves by family curves one by one?

Hi Pilou,

re:
> When you say "Join to glue them together into 2 closed curves" it's the 2 family's curves Joined
> in the same time or Join family curves by family curves one by one?

I mean with these 16 edge curves selected:



Run the Edit > Join command one time, that will generate a result of 2 closed curves each made of 8 segments. Then you can do one loft between those 2 closed curves rather than doing 8 lofts.

- Michael

<< that will generate a result of 2 closed curves each made of 8 segments

Thanks for the precision, that was not clear for me!

There is not the possibility that the "Naked" function takes also some alone segments
existing faraway for any reason inside the 3D space ?
These 2 famillies of curves will be closed also in this case?

Hi Pilou,

> There is not the possibility that the "Naked" function take also some segments
> existing faraway for any reason inside the 3D space ?

It's helpful to hide such other faraway objects so you can focus on the one at hand and not have that problem.

- Michael