Brep to mesh puzzles

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Permalink Reply by Giulio Piacentino on April 20, 2015 at 1:52am

Hi Peter

>>Mesh[] terrainM = Mesh.CreateFromBrep(terrain, MeshingParameters.Default); should yield a closed mesh or not?

Usually yes, but not always. This returns brep faces as meshes. This is a choice of the current mesher, and it allows you to choose how to proceed. For example, there are some MeshingParameter settings for which faces will not join, thus, even after joining, creating open meshes.

Mesh[] terrainMU = Mesh.CreateBooleanUnion(terrainM); shouldn't create a closed mesh?

>> Sorry no. A solid Boolean union is the logic union of space surrounded by closed objects. Because most faces will be open, most of the times that union will not be what you obtain after joining all faces. The Grasshopper Mesh Brep component is programmed so that it will join those faces for you. We could add a Mesh.JoinAll() method to RhinoCommon to join all meshes, and it would be similar to this (except for some error checking):

Mesh CreateByJoiningAll(Mesh[] parts)
{
 Mesh full = new Mesh();
 foreach(Mesh m in parts){
  full.Append(m);
 }
 return full;
}

Giulio
--
Giulio Piacentino
for Robert McNeel & Associates
giulio@mcneel.com

Permalink Reply by peter fotiadis on April 20, 2015 at 2:08am

Hi Giulio,

Thanks of the info. In fact I did it exactly as you suggest (see  code portion captured above) using mesh.Append(i).

best, Peter