FreeCAD Forum

OS: Fedora 34 (Server Edition) (KDE)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.Unknown
Build type: Unknown
Python version: 3.9.4
Qt version: 5.15.2
Coin version: 4.0.0a
OCC version: 7.5.0

The roof on the building I'm modelling is quite complex. The best approach I found (in my limited knowledge of FreeCAD) is to create sketches for the various parts (most of them with a circumflex accent shape), extrude from the sketches to create slabs and perform boolean operations (intersection, differences and union) to get the final roof.

I now want to add skylights on this roof. Since it does not work on the global roof object (or I don't know how to do it), I attempt to create the window on the "most primitive" object, i.e. the slab resulting from sketch extrusion. I have no difficulty to attach a sketch on the slab face. I can create the window but it looks like it is not part of the slab: it remains an "independent" object in the tree view and therefore does not cut the slab (no hole in slab).

Is this because I create my window late in the process?

I noticed that when objects are grouped together, actions involving objects not in the same group are impossible or don't give the expected result. Should I create my windows as soon as I have created the slabs (roof slopes)?

Also all metric references are inside the face plane. In the case of skylight, I'd like to position the windows using other references, i.e. height above floor which is of course not a distance in the roof plane. How can I do that other than complicated math formula?

UPDATE: I found I must give the extruded shape "wall" attribute to get the window punched. But when I type the composite object "roof" later, visibility of window is made independent from the "roof", i.e. when I toggle roof visibility, the windows remains visible, as if floating in the air.

What am I doing wrong?

ajlittoz wrote: ↑Mon Sep 20, 2021 8:15 am
I now want to add skylights on this roof. Since it does not work on the global roof object (or I don't know how to do it), I attempt to create the window on the "most primitive" object, i.e. the slab resulting from sketch extrusion. I have no difficulty to attach a sketch on the slab face. I can create the window but it looks like it is not part of the slab: it remains an "independent" object in the tree view and therefore does not cut the slab (no hole in slab).

May better post your file and a few screencapture to better illustrate your proble:

For example, if your object is a Roof object, adding it to the Window's Host property will make it cut with an opening.

@paullee: working on samples, it appears order of construction for "complex" objects is very important. From my experimentation, it looks like all union/intersection/difference operations should take place first. Then this object is conferred attribute wall by selecting it and clicking on the wall tool.

After that, adding windows results in the usual cut operation and the window is really part of the "wall". When I toggle visibility, everything (all attached objects) also toggle.

Not yet tested with roof. Could you tell me what are the consequences of roof attribute? Will it cut walls into gables without the need of difference with complicated shapes?

ajlittoz wrote: ↑Mon Sep 20, 2021 2:06 pm Not yet tested with roof. Could you tell me what are the consequences of roof attribute? Will it cut walls into gables without the need of difference with complicated shapes?

A bit difficult to explain without a working sample

Anyway, to my understanding, every Arch Object works similarly. So if your shape is roof, you may 'encapsulate' it in a Roof object by similar workflow as you had done as Wall. I do not use ArchRoof, but should work according to the wiki.

Arch Window Wiki - "An Arch Window is a base object for all kinds of "embeddable" objects, such as windows and doors. It is designed to be either independent, or "hosted" inside another component such as an Arch Wall, Arch Structure, or Arch Roof. "

ajlittoz wrote: ↑Mon Sep 20, 2021 8:15 am

here is a suggestion

https://www.youtube.com/watch?v=B6CH7BQg16Q








the roof was created in this way

https://www.youtube.com/watch?v=Dkpyux4-0g4

Thanks to all.

The key to the solution is to add doors or windows as the very last step in construction (nearly like in the real work, the difference being the hole is made when building the wall). Thus, the door/window is considered part of the composite object (it is only 1-level deeper in the group) and composite visibility is applied to the door/window. Also face attachment seems to be more stable and reliable.

Example: