[CE U13.1 C#] How to work with Type 19 Solid in LocateSubEntityTool?

Question

Hi, 
 I am working on a tool designed for 3D operations with solid, where one from possible inputs can be old solid (element type 19). 
 I am aware of a fact that not ISolidKernelEntity (which I guess is also type 19) has limited support, but I was not able to implement any working code that would allow me to access the solid geometry. 
 The tools is "read only / query tool", so IsModifyOriginal returns true. I am not sure what is a right value returned from OnPreElementModify. 
 I am able to select the solid and its face(s), but I failed to do anything in OnElementModify: 
 public override StatusInt OnElementModify(Element element)
{
 SubEntity[] subEntities = new SubEntity[0];
 this.GetAcceptedSubEntities(ref subEntities);
 // Ok, I receive accepted faces

 for (int i = 0; i < subEntities.Length; i++)
 {
 SubEntity face = subEntities[i];

 IntPtr geom = default(IntPtr);
 BentleyStatus getGeometryStatus = this.GetSubEntityGeometry(geom, face);
 // getGeometryStatus is SUCCESS, but the pointer is always zero ... no data

 SubEntity[] vertices;
 BentleyStatus getFaceVerticesStatus = SolidUtil.GetFaceVertices(out vertices, face);
 // getFaceVerticesStatus is always ERROR
 }

 // Element is not modifed
 // From C++ documentation: ERROR to reject change or if change completely handled by tool.
 return StatusInt.Error;
} 
 I also tried to overwrite 
 protected override BentleyStatus OnProcessSolidPrimitive(ref SolidPrimitive geomPtr, DisplayPath path)
{
 return BentleyStatus.Error;
} 
 but the results are always the same regardless Error or Success is returned. It seems the method is never called, I was not able to reach a break point in Debug or to print a message from the method :-( 
 I would like to know whether I do anything wrong (e.g. to override some other method?) or there is a bug in the code (maybe two bugs? ... OnProcessSolidPrimitve not called and GetSubEntityGeometry returns success but not pointer?). 
 Ultimately, I need to obtain: 
 
 geometry (and vertices), when a user selects face 
 curve (and end points), when a user selects edge 
 point, when a user selects vertex 
 
 With regards, 
 Jan

Brien Bastings · Accepted Answer

Hey Jan, 
 The non-brep types lack any sort of connectivity information, so what you can do with them is very limited. You can pick a face, edge, or vertex and get it's geometry, but that's about it, you can't ask an edge for the surrounding faces, a vertex for the surrounding edges, etc. you only get this information when you have brep topology. 
 The SolidUtil methods are for working with breps ( ISolidKernelEntity) , so it's not expected for them to support a non-brep ISubEntity. Unlike a brep sub-entity, the non-brep sub-entities are not valid after the LocateSubEntityTool exits as it's the tool that holds the connection to the original surface/solid to provide even the minimal topology support that it does. 
 //! Return true if the supplied subEntity represents an face, edge, or vertex of an ISolidKernelEntity and is valid for the solid modelling api. DGNVIEW_EXPORT bool LocateSubEntityTool:: IsSolidKernelSubEntity (ISubEntityCR subEntity); 
 That said, what you are looking to do is possible (using C++ at least) without trying to promote everything to brep: 
 Jan Šlegr said: Ultimately, I need to obtain: 
 
 geometry (and vertices), when a user selects face 
 curve (and end points), when a user selects edge 
 point, when a user selects vertex 
 There's the tool method you discovered to get the geometry from a sub-entity, and the C++ version should certainly return a valid IGeometryPtr. 
 //! Get an IGeometryPtr that holds the geometric representation for the supplied sub-entity. DGNVIEW_EXPORT BentleyStatus LocateSubEntityTool::GetSubEntityGeometry (IGeometryPtr& geom, ISubEntityCR subEntity); 
 For a planar face, the IGeometry returned will be a region CurveVector and it will be easy enough to collect the vertices. A non-planar face can be returned as a surface or revolution or ruled sweep...if you need to get vertices from these, you'll have to get the edges curves and extract the vertices from those. 
 For an edge, the IGeometry will be an open CurveVector containing a single CurvePrimitive that you can ask for the start/end points. 
 For a vertex, I believe the IGeometry will be a "none" boundary type CurveVector containing a single point string CurvePrimitve. 
 * For an edge or vertex you could also use LocateSubEntityTool::TryGetAsCurveLocationDetail instead to get both the CurvePrimitive and pick information... 
 HTH 
 -B 
 Jan Šlegr said: I would like to know whether I do anything wrong (e.g. to override some other method?) or there is a bug in the code (maybe two bugs? ... OnProcessSolidPrimitve not called and GetSubEntityGeometry returns success but not pointer?). 
 Yes, these do sound like bugs, I can only vouch for the C++ api and not the wrappers... 
 -B

[CE U13.1 C#] How to work with Type 19 Solid in LocateSubEntityTool?

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