Merge coplanar faces not working

[Sven_Duplić]

Hello, I have a closed polysurface like this and I want to merge all coplanar faces. When I use the standard command (merge all coplanar faces), the faces get merged as expected, but when I use ‘MergeCoplanarFaces’ in rhinocommon using c#, it doesn’t work as expected.

Here is some additional info, and the file with the geometry (at the end of the screenshots). Any help is greatly appreciated as I have no idea why this is occuring.

… maybe these arrows are the issue?

Also, these are trimmed surfaces (3), the rest are untrimmed.

solid.3dm (120.3 KB)

[martinsiegrist]

Can you share the script you’re trying to run?

[Sven_Duplić]

The script if longer than this, but I’ll share the most relevant part.

The basic idea of the script is to create a simple wall and floor schema. The idea is to get a simple polysurface that would show the walls of the room with the floor, like this:

I derive this schema from the following geometry - the inner box of the room (shown yellow) and the outer box of the room (shown green)

I further conceptually divide these boxes into ‘lower’ part (where the floor will be) and ‘upper part’ (where walls will be). I basically use plane intersections to get the curves that I’ll use to construct the final schema - in this example the curves are the red bottom one (for the floor) and blue ones (for the walls). Each of the parts will get extruded up a specific height (in this case the floor will get extruded 20 cm, walls 260 cm).

When I get the curves (called BDsAndClusterCuts below), I than extrude the curves to first form the vertical surfaces for both the ‘upper’ and the ‘lower’ part respectively.

var BDsAndClusterCuts = new List<Curve>();
BDsAndClusterCuts.AddRange(BDAcuts); // BDAcuts are cuts with the yellow box
BDsAndClusterCuts.AddRange(clusterCuts); //clusterCuts are cuts with green box

List<Surface> surfaces = new List<Surface>();
Vector3d v = new Vector3d(0, 0, height);

foreach (var crv in BDsAndClusterCuts)
{
   var s = Extrusion.CreateExtrusion(crv, v);
   surfaces.Add(s);
}

foreach (var s in surfaces)
{
   var sToBrep = s.ToBrep();
   breps.Add(sToBrep); // this breps collection collects breps from both lower and upper parts
}

… which ends up looking like this:

I than simply try to do the following : join breps, merge breps, cap planar holes and merge coplanar faces:

 var joinedBreps = Brep.JoinBreps(breps, GlobalSettings.Tolerance);
 var mergedBreps = Brep.MergeBreps(joinedBreps, GlobalSettings.Tolerance);
 var cappedBreps = mergedBreps.CapPlanarHoles(GlobalSettings.Tolerance);
 cappedBreps.MergeCoplanarFaces(GlobalSettings.Tolerance);
 RhinoDoc.ActiveDoc.Objects.Add(cappedBreps);

… and I end up with the brep without the merged coplanar faces.

[dale (Dale Fugier)]

Hi @Sven_Duplić,

Try splitting kinky faces (BrepFaceList. SplitKinkyFaces) before capping and merging planar faces.

– Dale