Edge on a surface

[OsWeldo]

Hey guys,

I was wondering if there is a built-in function that allows me to check if an edge lies on a surface.

Best Regards.
Osweldo

[openBrain]

Is that planar edge/surface or curved ones ?

[OsWeldo]

Is that planar edge/surface or curved ones ?

Both actually.

[openBrain]

Both actually.

OK. Hopefully other more skilled forumers will weigh in, but IMO the curved case isn't so easy to handle... Did you have a search into OpenCasCade API ?

[OsWeldo]

Both actually.

OK. Hopefully other more skilled forumers will weigh in, but IMO the curved case isn't so easy to handle... Did you have a search into OpenCasCade API ?

I haven't, I'm actually not acquainted with OpenCasCade API, but I'll search! Thank you!

[Chris_G]

I was wondering if there is a built-in function that allows me to check if an edge lies on a surface.

About the wording : you are mixing topology ("edge") with geometry ("surface")
You can check if an edge has a Curve2D representation on a face :

Code: Select all

aFace.curveOnSurface(anEdge)

will return a curve2D, and first / last parameters, or nothing.
But this is not a perfect test.
It may return nothing (if edge and face have no "historic" relation), although the edge may effectively lie on the face.
We're lacking some more information on the context.

[alberich]

I was wondering if there is a built-in function that allows me to check if an edge lies on a surface.

For clarification, do you want to know (a) if the edge is part of/belongs to a surface; that is if the edge is part of what defines the surface

or

(b) if the edge of, say, object1 contacts a surface of, say, object2?

[OsWeldo]

I was wondering if there is a built-in function that allows me to check if an edge lies on a surface.

About the wording : you are mixing topology ("edge") with geometry ("surface")
You can check if an edge has a Curve2D representation on a face :

Code: Select all

aFace.curveOnSurface(anEdge)

will return a curve2D, and first / last parameters, or nothing.
But this is not a perfect test.
It may return nothing (if edge and face have no "historic" relation), although the edge may effectively lie on the face.
We're lacking some more information on the context.

It was in fact what happened, it returned nothing, because the lines are projected on the surface.
I'll leave a picture so you can analyze.

[OsWeldo]

I was wondering if there is a built-in function that allows me to check if an edge lies on a surface.

For clarification, do you want to know (a) if the edge is part of/belongs to a surface; that is if the edge is part of what defines the surface

or

(b) if the edge of, say, object1 contacts a surface of, say, object2?

I want to know just if contacts, so (b)!

[chrisb]

I was pondering how I would do it manually. For a test I created a non solid cylinder and sketches of the same diameter. I then made a boolean common and checked the result with CheckGeometry.

I investigated the following cases:

- Sketch on surface: CheckGeometry is ok and shows a length for the resulting wire
- Sektch and surface are disjoint: CheckGeometry shows an invalid compound
- Sektch and surface are tangent: CheckGeometry shows an invalid compound
- Sektch and surface have two points in common: CheckGeometry shows an invalid compound, I expect the same result for one intersection point

So Boolean common could be a way for your check. However, seeing the now and then occurring coplanar issues I would not really guarantee for it.