Add SkeletonProjector & use it in MeshLiaison

amibe/src/org/jcae/mesh/amibe/algos3d/RemeshSkeleton.java

@@ -21,6 +21,7 @@
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Iterator;
 import java.util.List;
 import java.util.NoSuchElementException;
@@ -114,6 +115,7 @@ public void compute()
 		EdgesCollapserNG edgeCollapser = new EdgesCollapserNG(mesh);
 		main: for(List<Vertex> polyline: skeleton.getPolylinesVertices())
 		{
+			int[] groups = null;
 			RemeshPolyline rp = new RemeshPolyline(mesh, polyline, metric);
 			rp.setBuildBackgroundLink(true);
 			List<Vertex> toInsert = rp.compute();
@@ -160,9 +162,14 @@ else if(dd <= tolerance)
 					Vertex oldDestination = toSplit.destination();
 					mesh.vertexSplit(toSplit, v);
 					liaison.addVertex(v, toSplit.getTri());
-					//TODO this will be slow as as toSplit.getTri() may be far
-					//from the wanted triangle so we will loop on all triangles
-					liaison.move(v, v, true);
+					if(groups == null) {
+						// Lazily get the list of groups which is the same for all edges of this polyline
+						groups = getGroups(toSplit);
+					} else {
+						assert(Arrays.equals(groups, getGroups(toSplit)));
+					}
+					boolean r = liaison.moveToClosestEdge(v, groups);
+					assert(r);
 					AbstractHalfEdge e = getEdge(v, oldDestination);
 					edgeIndex.set(segId, e);
 					swapVolume = m2 * m2 * m2 / 64;
@@ -178,6 +185,18 @@ else if(dd <= tolerance)
 		}
 	}
 
+	private static int[] getGroups(AbstractHalfEdge edge) {
+		Iterator<AbstractHalfEdge> it = edge.fanIterator();
+		List<Integer> r = new ArrayList<Integer>();
+		while(it.hasNext()) {
+			r.add(it.next().getTri().getGroupId());
+		}
+		// convert the ArrayList to int[]
+		int[] rr = new int[r.size()];
+		for(int i = 0; i < rr.length; i++)
+			rr[i] = r.get(i);
+		return rr;
+	}
 	public static void main(final String[] args) {
 		try {
 			Mesh mesh = new Mesh();

amibe/src/org/jcae/mesh/amibe/metrics/Location.java

@@ -164,4 +164,44 @@ public double distance3D(Location end)
 	public String toString() {
 		return "(" + x + ", " + y + ", " + z + ")";
 	}
+
+	public static double dot(double[] v1, double[] v2)
+	{
+		return v1[0] * v2[0] + v1[1] * v2[1] + v1[2] * v2[2];
+	}
+
+	/**
+	 * Return the distance between this and an edge
+	 * @param origin the origin of the edge
+	 * @param destination the destination of the edge
+	 * @param projection the projection of this on the edge
+	 * @return the square of the distance
+	 */
+	public double sqrDistance3D(Location origin, Location destination, Location projection) {
+		// adapted from https://www.geometrictools.com/GTEngine/Include/Mathematics/GteDistPointSegment.h
+		double direction[] = new double[3];
+		destination.sub(origin, direction);
+		double diff[] = new double[3];
+		sub(destination, diff);
+		if(dot(direction, diff) < 0) {
+			projection.moveTo(origin);
+			sub(origin, diff);
+			double t = dot(direction, diff);
+			if (t > 0)  {
+				double sqrLength = dot(direction, direction);
+				if (sqrLength > 0) {
+					t /= sqrLength;
+					projection.moveTo(
+						origin.getX() + t * direction[0],
+						origin.getY() + t * direction[1],
+						origin.getZ() + t * direction[2]);
+				}
+			}
+		} else {
+			projection.moveTo(destination);
+		}
+
+		sub(projection, diff);
+		return dot(diff, diff);
+	}
 }

amibe/src/org/jcae/mesh/amibe/projection/MeshLiaison.java

@@ -40,6 +40,7 @@
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import org.jcae.mesh.amibe.metrics.Location;
+import static org.jcae.mesh.amibe.metrics.Location.dot;
 import org.jcae.mesh.amibe.util.HashFactory;
 
 public abstract class MeshLiaison
@@ -49,6 +50,7 @@ public abstract class MeshLiaison
 	protected final Mesh backgroundMesh;
 	protected final Mesh currentMesh;
 	private Skeleton skeleton;
+	private SkeletonProjector skeletonProjector;
 
 	protected final double [] work1 = new double[3];
 	protected final double [] work2 = new double[3];
@@ -229,6 +231,20 @@ public final boolean move(Vertex v, Location target, int group, boolean doCheck)
 
 	protected abstract boolean move(Vertex v, Location target, boolean backup,  int group, boolean doCheck);
 
+	/**
+	 * Get the projection of a vertex on the closest edge of the skeleton (list of edge which are non-manifold or
+	 * border of groups)
+	 * @param v the vertex being projected
+	 * @param groups the list of adjacent groups around the edge (all edges will be tested if empty)
+	 * @return true if a projection has been found
+	 */
+	public boolean moveToClosestEdge(Vertex v, int ... groups) {
+		if(skeletonProjector == null) {
+			skeletonProjector = new SkeletonProjector(backgroundMesh);
+		}
+		return skeletonProjector.moveToClosestEdge(v, groups);
+	}
+
 	public final boolean project(Vertex v, Location target, Vertex start)
 	{
 		throw new RuntimeException("Not implemented yet");
@@ -598,11 +614,6 @@ private static double norm2(double[] v)
 		return v[0] * v[0] + v[1] * v[1] + v[2] * v[2];
 	}
 
-	private static double dot(double[] v1, double[] v2)
-	{
-		return v1[0] * v2[0] + v1[1] * v2[1] + v1[2] * v2[2];
-	}
-
 	public static class TriangleDistance
 	{
 		private double s, t;

amibe/src/org/jcae/mesh/amibe/projection/SkeletonProjector.java

@@ -0,0 +1,64 @@
+/* jCAE stand for Java Computer Aided Engineering. Features are : Small CAD
+   modeler, Finite element mesher, Plugin architecture.
+
+    Copyright (C) 2019, by Airbus S.A.S.
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
+
+package org.jcae.mesh.amibe.projection;
+
+import org.jcae.mesh.amibe.algos3d.Skeleton;
+import org.jcae.mesh.amibe.ds.AbstractHalfEdge;
+import org.jcae.mesh.amibe.ds.Mesh;
+import org.jcae.mesh.amibe.ds.Vertex;
+import org.jcae.mesh.amibe.metrics.Location;
+
+import java.util.Collection;
+import java.util.List;
+
+/** Project points on the skeleton of a mesh */
+public class SkeletonProjector {
+    private final Skeleton skeleton;
+
+    public SkeletonProjector(Mesh mesh) {
+        skeleton = new Skeleton(mesh, 0);
+    }
+
+    public boolean moveToClosestEdge(Vertex v, int[] groups) {
+        Collection<List<AbstractHalfEdge>> polylines;
+        if(groups.length == 0)
+            polylines = skeleton.getPolylines();
+        else
+            polylines = skeleton.getPolylines(groups);
+        double minDistSqr = Double.POSITIVE_INFINITY;
+        Location projection = new Location();
+        Location bestProjection = new Location();
+        boolean found = false;
+        // TODO: This is O(n) for each vertex so O(n^2) to move all vertices. If this is too slow we should rework
+        // TriangleKdTree to ObjectKdTree<Triangle or AbstractHalfEdge> and use it to find the closest edge.
+        for(List<AbstractHalfEdge> p: polylines) {
+            for(AbstractHalfEdge edge: p) {
+                double distSqr = v.sqrDistance3D(edge.origin(), edge.destination(), projection);
+                if(distSqr < minDistSqr) {
+                    found = true;
+                    bestProjection.moveTo(projection);
+                    minDistSqr = distSqr;
+                }
+            }
+        }
+        v.moveTo(bestProjection);
+        return found;
+    }
+}