Jump to content
Phileas

Fitting a slab to the slope of another slab

Recommended Posts

OK so what I'm trying to achieve is:

278873_Capturedecran2019-01-30a13_52_37.thumb.png.5e17947a71dd6bbf6b637ae1d01afc40.png

 

I have a sloped slab (slopes for water draining purposes). This slab, made out of concrete covered with a thin sealing layer so the water can flow, is set to be covered with dirt in oder to have a vegetated surface. The surface of the dirt however isn't supposed to be sloped in the same way the supporting slab is. I want it to be even, and the thickness of the dirt layer to vary to match the slopes beneath it.

 

How do I do this?

Share this post


Link to post

image.thumb.png.0cd1247693ddb836f1861e80123d857f.pngCan you create a polygon and extrude it to the width of the slab?

Share this post


Link to post

@David S I sure can do that. But wouldn't the extrude be the same thickness everywhere, thus not really following the slopes of the slab beneath it?

 

I could create a polygon, extrude it to the thickness of the dirt layer I want, the create a polygon for every side of the slope I have on the slab beneath by substracting volumes between an horizontal extrude and an inclined one, inclined to match the slope I want to fit it to, and then manually place and substract every slope from my original extrude, before placing it on the slab where I want it to be. 

But I want a better solution, because:

         - If I later change the slightest part of the slab, I have to rebuild the dirt layer completely from scratch

         - It will take hours

Edited by Phileas

Share this post


Link to post

and yes it's multi surfaces

there has to be a way for VW to calculate the slopes itself

Edited by Phileas

Share this post


Link to post

I suspect there is a way and maybe one of the nurbs surface experts can help you? I'm afraid I have a planning deadline but will experiment later!

  • Like 1

Share this post


Link to post

@David S take your time buddy, I have plenty of other details to fix and can just leave this slab on standby for a while, thanks for your help 🙂

Share this post


Link to post

What about using slab components? Set the concrete slab component to be tapered and set the green roof substrate to be a fixed thickness.

  • Like 1

Share this post


Link to post

^ This

 

I would also recommend the Slab Tool.

You can adjust which Slab Components will follow a slope and

which will stay level.

Share this post


Link to post

@Christiaan @zoomer I was pretty sure there had to be a way to do this using the slab tool.

But I can't figure it out, which makes me feel kinda stupid.

 

219352609_Capturedecran2019-01-31a09_18_50.thumb.png.1eaac4ace9f916bbdecdb7aa3d478bb8.png

No Matter what combination of slab origin (the arrow) and tapered component (the check) I try, I can't manage to get what I want.

Component number 3: the concrete slab, I want it's thickness to vary in order to create the slopes.

Component number 2: the sealing layer so the water can flow, I want it's thickness to be fixed, but it needs to follow the slopes.

Component number 1: the dirt layer, which I want to have a varying thickness so its lower face fits the slopes, and the upper face is horizontal.

 

If someone could show me how I achieve that, that'd be great

Share this post


Link to post

Hmmh, I don't get it to work either.

The Top of the Slab has to be always sloped ?

You can't happen the slope inside of the inner Components only ?

 

So either you need more Slabs in combination,

with tricks like negatively draining a Slab that is sloped in itself ?

 

Or is it just better to make the lower concrete Component Part have

the drainage slope, and use the option to add Solids to Slabs to

get the slope away from the soils top ?

  • Like 1

Share this post


Link to post

@zoomer Your idea to use solid addition to slabs seems promising

 

So I'd make an Extrude for the soil, but how do I then add it to the sloped concrete slab in order to have its lower face following the slopes?

Share this post


Link to post

Could you create a 3D polygon (profile) with a sloped base and horizontal top and sides and extrude it across the lower slab ?

If the base changes you would adjust the profile as needed

Share this post


Link to post

@bob cleaver The problem I had with 3D Polygons until now is that they have no fill in a section view. I need that soil layer to display a dirt fill when cut.

 

I could create the "mesh" for the layer, no problem, with a 3D polyline. Vectorworks then adds the surfaces between the edges you created, but no fill.

And you can't extrude a 3D Polygon like you extrude a 2D Rectangle for example, simply because the surface of said 3D Polygon is not horizontal, and vectorworks doesn't know how to extrude that (correct me if you know the reasons behind this better than me or if I'm wrong).

it's just like you can't draw a 2D rectangle shape, rotate it into a 3D direction, and then extrude it. VW doesn't know how to do that.

Share this post


Link to post

I do have a solution for my problem, but it'll take hours, and I'd have to repeat it completely from scratch if I change something within the concrete slab:

 

  • Make a 2D Polygon in the shape of one of the faces of the slope.
  • Extrude it, so it's lower face is on the altitude of the drain, and the upper face on the altitude of the starting point of the slope.
  • Copy it, so you have the same object twice. That object is an extrude of a 2D Polygon.
  • place the copy on top of the original one
  • Rotate it downwards, so that one side of the copy is still sitting on top of the original and the other one is intersecting the lower face of the original.
  • Go to a top/plan view, and adjust the size of the rotated copy, so it is overall bigger than the original. (you can't do the next step immediately, because the 2D Projection of a rotated object is smaller than the un-rotated original, so solid substracting it immediately without resizing it would leave small parts of the original object unaffected))
  • and then use a "solid substraction" operation to substract the copy from the original object. you now have an extrude wit a top surface showing the same slope as one of the faces of the sloped concrete slab.

 

  • Repeat this for every single face of the slope of the concrete slab
  • adjust all the faces to form a "copy" of the slope of the concrete slab
  • add volumes, so that all the extrudes you just ceated form one single object
  • create a slab for the soil
  • move the addition of extrudes you created underneath the soil slab, with its sloped side intersecting the soil slab.
  • use the "substract Polygon from slab" command to reshape the slab with the extrudes you created

now you have a soil slab with a horizontal upper face, and a sloped lower face following the slopes of the concrete slab. you just have to put it into it's final location.

 

As I said, this takes hours, and if you change a single face of the sloped concrete slab, the soil slab's lower face doesn't match the slopes anymore

 

there has to be a better way to do this... Or it's a big missing part of the slab tool

Edited by Phileas

Share this post


Link to post

image.thumb.png.e04716d24790574de15cceb8432f2f15.png

 

Im probably missing a lot in translation but this is a mix of solid subtractions/slabs The slab right has a horizontal flat top but a clear fit into the slab to the left mirroring the slopes??

 

 

  • Like 1

Share this post


Link to post

@David S Yeah that's the idea exactly you got it right

 

this takes forever to achieve when your slab's slope has 5 or more faces though...

 

Would be much easier if it was at least possible to substract a slab from an extrude (I only see "substract extrude from slab" in VW and not the other way around)

 

Or substracting slabs from slabs would work as well

 

Or simply optimizing the slab tool... I feel like there is something missing here...

 

I'd still like @zoomer to explain his idea to use solid additions to slabs though, this sounded promising

 

If I find a solution I'll give the exact instructions with screenshots on how to solve this kind of problem

Share this post


Link to post

My approach to this would be the same as I take with walls when the VW tool can't produce what I want, which would be just to revert to direct solid modelling. I'd make the concrete element to the shape I want, then make an additional two objects using solids subtraction/addition, one for the sealing layer and one for the dirt/earth. I'd then give them the necessary attributes to show up as you desire in sections etc.

  • Like 1

Share this post


Link to post

@line-weight Yeah that is probably the best thing to do... still quite frustrating...

 

I hope that one day we'll reach a level of precision with the VW tools that'll allow us to use only the tools and almost no solid modeling

Share this post


Link to post
1 hour ago, Phileas said:

@line-weight Yeah that is probably the best thing to do... still quite frustrating...

 

I hope that one day we'll reach a level of precision with the VW tools that'll allow us to use only the tools and almost no solid modeling

 

Yes. Who knows, that day might even come while some of us are still alive.

  • Laugh 2

Share this post


Link to post

Seriously though, as I don't think it's going to change for some time, I think it's worth developing a strategy where you identify the cases where the VW tools allow you to do what you want, and accept that it's quicker just to do the rest with solid modelling rather than fighting the system (it's taken me a while to realise this).

Share this post


Link to post

Typically I find that the % of a model you can do with the standard tools decreases drastically the further into the detailed design process you go. So I do use the standard tools a fair bit for early stage designs where it's 'near enough'. Then getting into more detail its not unusual for every single window and many portions of walls and all staircases to become solid modelled objects (obviously the type of design will have an impact on how much this is the case).

  • Like 1

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

 

7150 Riverwood Drive, Columbia, Maryland 21046, USA   |   Contact Us:   410-290-5114

 

© 2018 Vectorworks, Inc. All Rights Reserved. Vectorworks, Inc. is part of the Nemetschek Group.

×