BUG: Sets Face Label for virtual boundary to -1 in SurfaceNetsFilter

- This makes the value consistent with QuickMesh
- Added documentation on the pros, cons and Face Labels for this filter.

Signed-off-by: Michael Jackson <[email protected]>

src/Plugins/SimplnxCore/docs/SurfaceNetsFilter.md

@@ -58,9 +58,19 @@ Nodes that appear on the exterior of a volume have Node Type values starting at
 
 ![Exterior Node Types](Images/SurfaceNets_NodeType_Exterior.png)
 
+### Exterior or Boundary Faces
+
+Triangle faces that bound the virtual volume will have one of the Face Labels components
+set to a value of -1. If you want to filter out those triangles, you can set any
+triangle face where at least one of the Face Labels = -1 to be filtered out. You can also
+run a Threshold Objects (Advanced) filter, those face labels as "TRUE" instead and 
+then run the "Remove Marked Triangles" filter to remove them from the surface mesh.
+
 ## Notes
 
-This filter should be used in place of the "QuickMesh Surface Filter".
+- This filter can be used in place of the "QuickMesh Surface Filter" and "Laplacian Smoothing Filter".
+- This filter can use substantially more memory than the QuickMesh Filter
+
 
 
 % Auto generated parameter table will be inserted here

src/Plugins/SimplnxCore/src/SimplnxCore/Filters/Algorithms/SurfaceNets.cpp

@@ -254,11 +254,11 @@ Result<> SurfaceNets::operator()()
       const bool isQuadFrontFacing = (quadLabels[0] < quadLabels[1]);
       if(quadLabels[0] == MMSurfaceNet::Padding)
       {
-        quadLabels[0] = 0;
+        quadLabels[0] = -1;
       }
       if(quadLabels[1] == MMSurfaceNet::Padding)
       {
-        quadLabels[1] = 0;
+        quadLabels[1] = -1;
       }
 
       getQuadTriangleIDs(vData, isQuadFrontFacing, triangleVtxIDs);
@@ -314,11 +314,11 @@ Result<> SurfaceNets::operator()()
       const bool isQuadFrontFacing = (quadLabels[0] < quadLabels[1]); ///
       if(quadLabels[0] == MMSurfaceNet::Padding)
       {
-        quadLabels[0] = 0;
+        quadLabels[0] = -1;
       }
       if(quadLabels[1] == MMSurfaceNet::Padding)
       {
-        quadLabels[1] = 0;
+        quadLabels[1] = -1;
       }
       getQuadTriangleIDs(vData, isQuadFrontFacing, triangleVtxIDs);
       t1 = {static_cast<usize>(triangleVtxIDs[0]), static_cast<usize>(triangleVtxIDs[1]), static_cast<usize>(triangleVtxIDs[2])};
@@ -372,11 +372,11 @@ Result<> SurfaceNets::operator()()
       const bool isQuadFrontFacing = (quadLabels[0] < quadLabels[1]);
       if(quadLabels[0] == MMSurfaceNet::Padding)
       {
-        quadLabels[0] = 0;
+        quadLabels[0] = -1;
       }
       if(quadLabels[1] == MMSurfaceNet::Padding)
       {
-        quadLabels[1] = 0;
+        quadLabels[1] = -1;
       }
       getQuadTriangleIDs(vData, isQuadFrontFacing, triangleVtxIDs);
       t1 = {static_cast<usize>(triangleVtxIDs[0]), static_cast<usize>(triangleVtxIDs[1]), static_cast<usize>(triangleVtxIDs[2])};