Support constrainting vertices to an IProjectionTarget in Remesher. Also handled an issue where we were not necessarily preserving topology of edge constraints (see can_collapse_constraints()).

Project-to-target-surface policy is now configrable, can be disabled, done as a post-process, or done inline.
Added DoDebugChecks, disabled by default but if enabled will do verification of constraints after each operation.

Author: rms80

geometry3Sharp.csproj

@@ -52,6 +52,7 @@
     <Compile Include="curve\Circle2.cs" />
     <Compile Include="curve\Ellipse2.cs" />
     <Compile Include="curve\NURBSCurve2.cs" />
+    <Compile Include="distance\DistPoint2Circle2.cs" />
     <Compile Include="distance\DistPoint3Circle3.cs" />
     <Compile Include="implicit\ImplicitField.cs" />
     <Compile Include="implicit\ImplicitOperators.cs" />
@@ -88,6 +89,7 @@
     <Compile Include="math\Vector3d.cs" />
     <Compile Include="math\Vector3i.cs" />
     <Compile Include="math\Vector3f.cs" />
+    <Compile Include="spatial\BasicProjectionTargets.cs" />
     <Compile Include="queries\Distance.cs" />
     <Compile Include="queries\MeshQueries.cs" />
     <Compile Include="queries\RayIntersection.cs" />
@@ -148,7 +150,6 @@
     <Compile Include="intersection\IntrRay3Box3.cs" />
     <Compile Include="shapes3\Circle3.cs" />
     <Compile Include="spatial\DMeshAABBTree.cs" />
-    <Compile Include="spatial\MeshProjectionTarget.cs" />
     <Compile Include="spatial\SpatialInterfaces.cs" />
   </ItemGroup>
   <ItemGroup>

mesh/MeshConstraints.cs

@@ -19,11 +19,21 @@ public enum EdgeRefineFlags
     public struct EdgeConstraint
     {
         EdgeRefineFlags refineFlags;
+        public IProjectionTarget Target;        // edge is associated with this projection Target.
+                                                // Currently only used as information, we do not explicitly
+                                                // project edges onto targets (must also set VertexConstraint)
 
 
         public EdgeConstraint(EdgeRefineFlags rflags)
         {
             refineFlags = rflags;
+            Target = null;
+        }
+
+        public EdgeConstraint(EdgeRefineFlags rflags, IProjectionTarget target)
+        {
+            refineFlags = rflags;
+            Target = target;
         }
 
         public bool CanFlip {
@@ -39,6 +49,10 @@ public bool NoModifications {
             get { return (refineFlags & EdgeRefineFlags.FullyConstrained) == EdgeRefineFlags.FullyConstrained; }
         }
 
+        public bool IsUnconstrained {
+            get { return refineFlags == EdgeRefineFlags.NoConstraint && Target == null; }
+        }
+
         static public readonly EdgeConstraint Unconstrained = new EdgeConstraint() { refineFlags = 0 };
     }
 
@@ -49,15 +63,29 @@ public struct VertexConstraint
         public bool Fixed;
         public int FixedSetID;      // in Remesher, we can allow two Fixed vertices with 
                                     // same FixedSetID to be collapsed together
+
+        public IProjectionTarget Target;    // vertex is constrained to lie on this projection Target.
+                                            // Fixed and Target are mutually exclusive
 
         public VertexConstraint(bool isFixed, int setID = InvalidSetID)
         {
             Fixed = isFixed;
             FixedSetID = setID;
+            Target = null;
         }
 
-        public const int InvalidSetID = -1;
-        static public readonly VertexConstraint Unconstrained = new VertexConstraint() { Fixed = false };
+        public VertexConstraint(IProjectionTarget target)
+        {
+            Fixed = false;
+            FixedSetID = InvalidSetID;
+            Target = target;
+        }
+
+        public const int InvalidSetID = -1;     // clients should interpret negative values as invalid
+                                                // (in case you wanted to use negative values for something else...)
+
+        static public readonly VertexConstraint Unconstrained = new VertexConstraint() 
+            { Fixed = false, FixedSetID = InvalidSetID, Target = null };
      }
 
 
@@ -119,5 +147,11 @@ public void ClearVertexConstraint(int vid)
         }
 
 
+        public System.Collections.IEnumerable VertexConstraintsItr() {
+            foreach (KeyValuePair<int,VertexConstraint> v in Vertices)
+                yield return v;
+        }
+
+
     }
 }