topic Application of void-extrusion/cut not possible for profiles with bevel in Revit API Forum

Application of void-extrusion/cut not possible for profiles with bevel

EliasScharlach — Mon, 29 Nov 2021 09:45:12 GMT

I am working on a plugin for Revit and enable the import of windows. In the course of this, 3-dimensional window-models are generated. For this, I automatically create profiles and void-extrusions via the API and apply a cut.

If the profile has a minimal bevel, it may not be possible to apply the void-extrusion/cut.

If you move the void-extrusion minimally, it can be applied. However, I want the void-extrusion to cut exactly the edge of the profile.

After days of investigation, I still don't fully understand when the void-extrusion is applicable and when it is not. If you increase the profile by extending the edge with the bevel in the cross section, the void-extrusion can be applied. According to this, it does not depend on the angle of the minimum bevel.

It is also not clear to me whether a too small line is created when applying the void-extrusion (limitation of Revit). In my opinion, this should not occur.

cross section of example2:

Questions:

Why, in part, can't the void-extrusion be applied?

Is there a way to detect this? Via the API?

I have created the following example, in which the problem should become clear.

Re: Application of void-extrusion/cut not possible for profiles with bevel

RPTHOMAS108 — Mon, 29 Nov 2021 11:26:59 GMT

You have to exaggerate the cut i.e. ensure that the edge of the solid doesn't lay on the face of the cutting void. In your two cases that fail this is likely the reason. You could likely extend sweep into centre of void to avoid this.

There are dimensional imperfections in these things. So placing the line on the face has 50/50 change of working depending on what side of the line it falls.

In example below if diagonal strikes horizontal face it will leave a tiny horizontal part of that face. If it strikes the vertical face it will leave a clean edge. Comes down to dimensional rounding as to which is chosen when you don't account for that.

There may be better approaches to what you are doing, using voids to create such details if often problematic unless you have nailed down the relationship between the cutting void and the edge of the solid being cut.

Re: Application of void-extrusion/cut not possible for profiles with bevel

EliasScharlach — Mon, 29 Nov 2021 14:32:59 GMT

Thanks for the quick reply. If I understand your answer correctly, it only works if the special profile with bevel protrudes completely inside the void and is not cut on one edge.

Example:

The issue is that I can't extend every profile. The profiles are automatically generated via API and due to the number of profiles the performance would suffer a lot. The approach you suggested I could still apply to the special profiles with bevel. However, this would require that I know when the cut cannot be applied.

For example, rectangular profiles I would not need to extend because Revit can cut them.

So I would need an API function or some other way to check whether Revit can apply the void or not (preferably during the creation process).

Generally a USP currently is to create specific extrusions as parametric elements. With meshes / directshape, the cuts are already working because we manipulate the mesh directly.

Is there an other approach for cuts on parametric extrusions?

Re: Application of void-extrusion/cut not possible for profiles with bevel

RPTHOMAS108 — Mon, 29 Nov 2021 18:08:35 GMT

I still lack the context of exactly why you can't extend the profile into the void. If you know it had the bevel you know it needs to be extended to cut it. There is no API approach other than to be notified of the failure and do it again the other way but that isn't something I would suggest doing.

I would perhaps consider doing a sweep blend across the thickness of the element and not a sweep along it's length i.e. eliminating the need for the void altogether. Incorporated the bevel into the two sweep blend profiles parametrically.

In the end if you create a family with lots of non parametric static solids using visibility to control which variation is visible then that type of family doesn't tend to perform well.

Re: Application of void-extrusion/cut not possible for profiles with bevel

EliasScharlach — Tue, 30 Nov 2021 08:30:38 GMT

Thanks for the answer. The second approach you mentioned is unfortunately not applicable for my use case, since the cross sections of the individual profiles can be significantly more complex than in the example described.
However, I will try / recheck the lengthening of the profiles in the coming weeks in a timely manner.