What is the simplest way to analyse a planar surface?

My goal is to determine if a face is a basic element (cylinder, sphere, disc, quadrilateral...).

In the case of the cylinder, the sphere or the cone, it's easy to do using the method IsKind( STANDARD_TYPE( Geom_SphericalSurface ))

But when the type of surface is planar, I don't know how to determine efficiently if the face correspond to a basic element (disc, quadrilateral, rectangle...)

For the moment I compute the number of edges in this face and the type of edges. And then I analyse these edges.
For example, the face is an entire disc if the number of edges is 2 and the types of edge is "circle".

Is it the way to do it or is it possible to do it more efficiently?
Thanks in advance


Roman Lygin's picture

Hi Elisa,

Not sure if I completely understood your need but I feel you mix two issues - type of the surface and shape of your element. Disc is not an analogue of a cylinder - indeed, you should distinguish between cylindrical and planar face. You can do so by IsKind(STANDARD_TYPE(Geom_Plane))...

Among planar elements you may want to distinguish among rectangles, disks/circles, triangles, etc. Then you may apply different checks if you know how these elements be represented. You can apply this checks for simple cases - e.g. triangle is bounded by a wire of 3 straight edges, disk is a single edge lying on Geom_Circle, etc.

For more complex cases you might benefit from the canonical recognition component (see among value-add software). It can concatenate several adjacent edges (e.g. several circular arcs into one) thus you could apply simple post-checks.

Hope this helps.

Roman Lygin