fix a bug in Rupperts algorithm and improve the edge length approximation function.

VadereMeshing/resources/poly/corner.poly

+# nVertices dimension nAttributes boundaryMarker
+10 2 0 0
+# vertexId x y
+1 0.500000 0.500000
+2 9.500000 0.500000
+3 7.000000 6.000000
+4 5.000000 8.000000
+5 3.000000 8.000000
+6 3.000000 4.000000
+7 7.000000 4.000000
+8 5.000000 6.000000
+9 0.500000 9.500000
+10 9.500000 9.500000
+#
+# nSegments boundaryMarker
+10 0
+# lineId vertexId1 vertexId2
+1 2 10
+2 10 9
+3 9 1
+4 1 2
+5 5 6
+6 6 7
+7 7 3
+8 3 8
+9 8 4
+10 4 5
+#
+# nHoles
+1
+# vertexId x y (of a vertex which lies inside the hole)
+1 4.666667 5.666667
\ No newline at end of file

VadereMeshing/resources/poly/corridor.poly

+# nVertices dimension nAttributes boundaryMarker
+12 2 0 0
+# vertexId x y
+1 0.500000 0.500000
+2 7.000000 5.000000
+3 7.000000 5.300000
+4 3.000000 4.300000
+5 9.500000 0.500000
+6 3.000000 5.300000
+7 3.000000 5.000000
+8 7.000000 4.300000
+9 3.000000 4.000000
+10 7.000000 4.000000
+11 0.500000 9.500000
+12 9.500000 9.500000
+#
+# nSegments boundaryMarker
+12 0
+# lineId vertexId1 vertexId2
+1 5 12
+2 12 11
+3 11 1
+4 1 5
+5 2 3
+6 3 6
+7 6 7
+8 7 2
+9 10 8
+10 8 4
+11 4 9
+12 9 10
+#
+# nHoles
+2
+# vertexId x y (of a vertex which lies inside the hole)
+1 5.000000 5.150000
+2 5.000000 4.150000
\ No newline at end of file

VadereMeshing/resources/poly/narrowCorridor.poly

+# nVertices dimension nAttributes boundaryMarker
+33 2 0 0
+# vertexId x y
+1 0.500000 0.500000
+2 2.300000 7.000000
+3 9.500000 0.500000
+4 2.800000 7.300000
+5 2.800000 6.500000
+6 4.800000 6.500000
+7 0.900000 6.600000
+8 1.200000 8.100000
+9 2.300000 7.200000
+10 2.800000 7.200000
+11 4.100000 7.000000
+12 5.000000 2.000000
+13 1.000000 6.500000
+14 1.300000 8.000000
+15 0.800000 6.600000
+16 7.000000 2.000000
+17 0.500000 9.500000
+18 1.100000 8.200000
+19 9.500000 9.500000
+20 4.000000 6.900000
+21 4.900000 6.600000
+22 1.400000 7.900000
+23 2.500000 6.700000
+24 2.700000 7.400000
+25 0.700000 6.700000
+26 4.900000 7.000000
+27 7.000000 5.000000
+28 2.200000 6.700000
+29 2.500000 7.400000
+30 5.000000 5.000000
+31 2.700000 6.500000
+32 2.100000 6.900000
+33 4.000000 6.100000
+#
+# nSegments boundaryMarker
+33 0
+# lineId vertexId1 vertexId2
+1 3 19
+2 19 17
+3 17 1
+4 1 3
+5 25 18
+6 18 8
+7 8 15
+8 15 25
+9 7 14
+10 14 22
+11 22 13
+12 13 7
+13 2 9
+14 9 29
+15 29 24
+16 24 4
+17 4 10
+18 10 5
+19 5 31
+20 31 23
+21 23 28
+22 28 32
+23 32 2
+24 16 27
+25 27 30
+26 30 12
+27 12 16
+28 33 20
+29 20 11
+30 11 26
+31 26 21
+32 21 6
+33 6 33
+#
+# nHoles
+5
+# vertexId x y (of a vertex which lies inside the hole)
+1 0.950000 7.400000
+2 1.150000 7.250000
+3 2.538272 6.968724
+4 6.000000 3.500000
+5 4.401111 6.647778
\ No newline at end of file

VadereMeshing/resources/poly/room.poly

+# nVertices dimension nAttributes boundaryMarker
+4 2 0 0
+# vertexId x y
+1 0.500000 0.500000
+2 9.500000 0.500000
+3 0.500000 9.500000
+4 9.500000 9.500000
+#
+# nSegments boundaryMarker
+4 0
+# lineId vertexId1 vertexId2
+1 2 4
+2 4 3
+3 3 1
+4 1 2
+#
+# nHoles
+0
+# vertexId x y (of a vertex which lies inside the hole)
\ No newline at end of file

VadereMeshing/src/org/vadere/meshing/examples/BackgroundMeshExamples.java

 package org.vadere.meshing.examples;
 
+import org.vadere.meshing.mesh.gen.MeshPanel;
+import org.vadere.meshing.mesh.impl.PMeshPanel;
 import org.vadere.meshing.mesh.impl.PSLG;
 import org.vadere.meshing.mesh.triangulation.EdgeLengthFunctionApprox;
+import org.vadere.meshing.mesh.triangulation.improver.eikmesh.impl.PEikMesh;
+import org.vadere.meshing.mesh.triangulation.triangulator.gen.GenRuppertsTriangulator;
+import org.vadere.meshing.mesh.triangulation.triangulator.impl.PContrainedDelaunayTriangulator;
+import org.vadere.meshing.mesh.triangulation.triangulator.impl.PDelaunayTriangulator;
 import org.vadere.meshing.mesh.triangulation.triangulator.impl.PRuppertsTriangulator;
 import org.vadere.meshing.utils.io.poly.PSLGGenerator;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.stream.Collectors;
 
 public class BackgroundMeshExamples {
 
 	public static void main(String ... args) throws IOException, InterruptedException {
-		greenlandLFS();
+		corridorLFS();
 	}
 
 	public static void greenlandLFS() throws IOException, InterruptedException {
 		final InputStream inputStream = MeshExamples.class.getResourceAsStream("/poly/kaiserslautern.poly");
 		PSLG pslg = PSLGGenerator.toPSLGtoVShapes(inputStream);
-		double theta = 10;
-
-		PRuppertsTriangulator ruppert = new PRuppertsTriangulator(
-				pslg,
-				p -> Double.POSITIVE_INFINITY,
-				theta
-		);
-
 		EdgeLengthFunctionApprox edgeLengthFunctionApprox = new EdgeLengthFunctionApprox(pslg);
 		edgeLengthFunctionApprox.printPython();
+	}
 
+	public static void roomLFS() throws IOException, InterruptedException {
+		final InputStream inputStream = MeshExamples.class.getResourceAsStream("/poly/room.poly");
+		PSLG pslg = PSLGGenerator.toPSLGtoVShapes(inputStream);
+		EdgeLengthFunctionApprox edgeLengthFunctionApprox = new EdgeLengthFunctionApprox(pslg, p -> 2.0);
+		edgeLengthFunctionApprox.printPython();
 	}
 
+	public static void cornerLFS() throws IOException, InterruptedException {
+		final InputStream inputStream = MeshExamples.class.getResourceAsStream("/poly/corner.poly");
+		PSLG pslg = PSLGGenerator.toPSLGtoVShapes(inputStream);
+		EdgeLengthFunctionApprox edgeLengthFunctionApprox = new EdgeLengthFunctionApprox(pslg, p -> 2.0);
+		edgeLengthFunctionApprox.printPython();
+	}
 
+	public static void corridorLFS() throws IOException, InterruptedException {
+		final InputStream inputStream = MeshExamples.class.getResourceAsStream("/poly/narrowCorridor.poly");
+		PSLG pslg = PSLGGenerator.toPSLGtoVShapes(inputStream);
+		EdgeLengthFunctionApprox edgeLengthFunctionApprox = new EdgeLengthFunctionApprox(pslg, p -> 2.0);
+		edgeLengthFunctionApprox.printPython();
+	}
 }

VadereMeshing/src/org/vadere/meshing/examples/EikMeshPlots.java

@@ -4,6 +4,7 @@ import org.vadere.meshing.mesh.gen.MeshPanel;
 import org.vadere.meshing.mesh.impl.PMeshPanel;
 import org.vadere.meshing.mesh.impl.PSLG;
 import org.vadere.meshing.mesh.inter.IPointConstructor;
+import org.vadere.meshing.mesh.triangulation.EdgeLengthFunctionApprox;
 import org.vadere.meshing.mesh.triangulation.IEdgeLengthFunction;
 import org.vadere.meshing.mesh.triangulation.improver.eikmesh.EikMeshPoint;
 import org.vadere.meshing.mesh.triangulation.improver.eikmesh.impl.PEikMesh;
@@ -56,7 +57,9 @@ public class EikMeshPlots {
 
 		kaiserslautern();
 		ruppertsAndEikMeshKaiserslautern();*/
-		bridge();
+		//bridge();
+		//roomLFS();
+		cornerLFS();
 	}
 
 	public static void randomDelaunay() throws IOException {
@@ -120,16 +123,84 @@ public class EikMeshPlots {
 		PSLG pslg = PSLGGenerator.toPSLGtoVShapes(inputStream);
 		Collection<VPolygon> holes = pslg.getHoles();
 		VPolygon segmentBound = pslg.getSegmentBound();
+		IDistanceFunction distanceFunction = IDistanceFunction.create(segmentBound, holes);
 
-		IPointConstructor<EikMeshPoint> pointConstructor = (x, y) -> new EikMeshPoint(x, y);
+		// (3) use EikMesh to improve the mesh
+		double h0 = 0.5;
+		var meshImprover = new PEikMesh(
+				distanceFunction,
+				p -> h0 + 0.5 * Math.abs(distanceFunction.apply(p)),
+				h0,
+				new VRectangle(segmentBound.getBounds2D()),
+				pslg.getHoles()
+		);
+
+		var meshPanel = new PMeshPanel(meshImprover.getMesh(), 1000, 800);
+		meshPanel.display("Combined distance functions " + h0);
+		while (!meshImprover.isFinished()) {
+			meshImprover.improve();
+			Thread.sleep(20);
+			meshPanel.repaint();
+		}
+		//meshImprover.generate();
+
+		write(toTexDocument(TexGraphGenerator.toTikz(meshImprover.getMesh(), f-> lightBlue, 1.0f)), "eikmesh_kaiserslautern_"+ Double.toString(h0).replace('.', '_'));
+
+		// display the mesh
+		meshPanel.display("Combined distance functions " + h0);
+	}
+
+	public static void roomLFS() throws IOException, InterruptedException {
+		final InputStream inputStream = MeshExamples.class.getResourceAsStream("/poly/room.poly");
+		PSLG pslg = PSLGGenerator.toPSLGtoVShapes(inputStream);
+		EdgeLengthFunctionApprox edgeLengthFunctionApprox = new EdgeLengthFunctionApprox(pslg, p -> 2.0);
+		edgeLengthFunctionApprox.printPython();
+
+
+		Collection<VPolygon> holes = pslg.getHoles();
+		VPolygon segmentBound = pslg.getSegmentBound();
 		IDistanceFunction distanceFunction = IDistanceFunction.create(segmentBound, holes);
 
+		// (3) use EikMesh to improve the mesh
+		double h0 = 0.5;
+		var meshImprover = new PEikMesh(
+				distanceFunction,
+				edgeLengthFunctionApprox,
+				h0,
+				new VRectangle(segmentBound.getBounds2D()),
+				pslg.getHoles()
+		);
+
+		var meshPanel = new PMeshPanel(meshImprover.getMesh(), 1000, 800);
+		meshPanel.display("Combined distance functions " + h0);
+		while (!meshImprover.isFinished()) {
+			meshImprover.improve();
+			Thread.sleep(20);
+			meshPanel.repaint();
+		}
+		//meshImprover.generate();
+
+		write(toTexDocument(TexGraphGenerator.toTikz(meshImprover.getMesh(), f-> lightBlue, 1.0f)), "eikmesh_kaiserslautern_"+ Double.toString(h0).replace('.', '_'));
+
+		// display the mesh
+		meshPanel.display("Combined distance functions " + h0);
+	}
+
+	public static void cornerLFS() throws IOException, InterruptedException {
+		final InputStream inputStream = MeshExamples.class.getResourceAsStream("/poly/corner.poly");
+		PSLG pslg = PSLGGenerator.toPSLGtoVShapes(inputStream);
+		EdgeLengthFunctionApprox edgeLengthFunctionApprox = new EdgeLengthFunctionApprox(pslg, p -> 1.0);
+		edgeLengthFunctionApprox.printPython();
+
+		Collection<VPolygon> holes = pslg.getHoles();
+		VPolygon segmentBound = pslg.getSegmentBound();
+		IDistanceFunction distanceFunction = IDistanceFunction.create(segmentBound, holes);
 
 		// (3) use EikMesh to improve the mesh
 		double h0 = 1.0;
 		var meshImprover = new PEikMesh(
 				distanceFunction,
-				p -> h0 + 0.5 * Math.abs(distanceFunction.apply(p)),
+				edgeLengthFunctionApprox,
 				h0,
 				new VRectangle(segmentBound.getBounds2D()),
 				pslg.getHoles()

VadereMeshing/src/org/vadere/meshing/mesh/impl/PSLG.java

@@ -101,6 +101,18 @@ public class PSLG {
 		this(segmentBound, holes, segments, points, new HashSet<>());
 	}
 
+	public PSLG conclose(@NotNull final VRectangle rectangle) {
+		if(!rectangle.contains(segmentBound.getBounds2D())) {
+			throw new IllegalArgumentException();
+		}
+		ArrayList<VLine> newLines = new ArrayList<>(segments.size() + segmentBound.getLinePath().size());
+		newLines.addAll(segments);
+		newLines.addAll(segmentBound.getLinePath());
+		PSLG pslg = new PSLG(new VPolygon(rectangle), holes, newLines, points);
+		pslg.protectionDiscs.addAll(this.protectionDiscs);
+		return pslg;
+	}
+
 	public PSLG addLines(@NotNull final Collection<VLine> lines) {
 		ArrayList<VLine> newLines = new ArrayList<>(segments.size() + lines.size());
 		newLines.addAll(segments);

VadereMeshing/src/org/vadere/meshing/mesh/triangulation/EdgeLengthFunctionApprox.java

@@ -11,10 +11,12 @@ import org.vadere.meshing.mesh.inter.IPointConstructor;
 import org.vadere.meshing.mesh.triangulation.triangulator.impl.PRuppertsTriangulator;
 import org.vadere.util.geometry.GeometryUtils;
 import org.vadere.util.geometry.shapes.IPoint;
+import org.vadere.util.geometry.shapes.VRectangle;
 import org.vadere.util.math.InterpolationUtil;
 
 import java.util.Comparator;
 import java.util.PriorityQueue;
+import java.util.function.Function;
 
 public class EdgeLengthFunctionApprox implements IEdgeLengthFunction {
 
@@ -22,10 +24,18 @@ public class EdgeLengthFunctionApprox implements IEdgeLengthFunction {
 
 	private static final String propName = "edgeLength";
 
-	public EdgeLengthFunctionApprox(@NotNull final PSLG pslg) {
+	public EdgeLengthFunctionApprox(
+			@NotNull final PSLG pslg,
+			@NotNull final Function<IPoint, Double> circumRadiusFunc) {
 
 		//IPointConstructor<DataPoint<Double>> pointConstructor = (x, y) -> new DataPoint<>(x, y);
-		var ruppertsTriangulator = new PRuppertsTriangulator(pslg, 10);
+		/**
+		 * Add a bound around so the edge function is also defined outside.
+		 */
+		VRectangle bound = GeometryUtils.boundRelative(pslg.getSegmentBound().getPoints(), 0.3);
+		PSLG boundedPSLG = pslg.conclose(bound);
+
+		var ruppertsTriangulator = new PRuppertsTriangulator(boundedPSLG, circumRadiusFunc, 10, false);
 		triangulation = ruppertsTriangulator.generate();
 
 		//TODO: maybe transform into an immutable triangulation / mesh!
@@ -37,7 +47,7 @@ public class EdgeLengthFunctionApprox implements IEdgeLengthFunction {
 		for(var v : vertices) {
 			double minEdgeLen = Double.MAX_VALUE;
 			for(var u : triangulation.getMesh().getAdjacentVertexIt(v)) {
-				double len = v.distance(u);
+				double len = v.distance(u) * 0.9;
 				if(len < minEdgeLen) {
 					minEdgeLen = len;
 				}
@@ -47,6 +57,11 @@ public class EdgeLengthFunctionApprox implements IEdgeLengthFunction {
 		}
 	}
 
+	public EdgeLengthFunctionApprox(@NotNull final PSLG pslg) {
+		this(pslg, p -> Double.POSITIVE_INFINITY);
+		//IPointConstructor<DataPoint<Double>> pointConstructor = (x, y) -> new DataPoint<>(x, y);
+	}
+
 	public void smooth(double g) {
 		assert g > 0;
 		// smooth the function based such that it is g-Lipschitz

VadereMeshing/src/org/vadere/meshing/mesh/triangulation/improver/eikmesh/gen/GenEikMesh.java

@@ -512,6 +512,8 @@ public class GenEikMesh<V extends IVertex, E extends IHalfEdge, F extends IFace>
 		double desiredLen = getDesiredEdgeLength(p1, p2);
 		double ratio = len / desiredLen;
 		double absForce = f.apply(ratio);
+		//System.out.println(len);
+		//System.out.println(desiredLen);
 		VPoint force = p1p2.setMagnitude(absForce * desiredLen);
 		return force;
 	}

VadereMeshing/src/org/vadere/meshing/mesh/triangulation/triangulator/gen/GenRuppertsTriangulator.java

@@ -356,6 +356,9 @@ public class GenRuppertsTriangulator<V extends IVertex, E extends IHalfEdge, F e
 				split(segment);
 			}
 		}
+
+		// we require this because split may other edges which are not direct neighbours encroached!
+		refineSimplex1D();
 	}
 
 	private void deEncrocheSgements() {
@@ -490,7 +493,20 @@ public class GenRuppertsTriangulator<V extends IVertex, E extends IHalfEdge, F e
 		return p.distance(line.getVPoint1()) > GeometryUtils.DOUBLE_EPS && p.distance(line.getVPoint2()) > GeometryUtils.DOUBLE_EPS && diameterCircle.contains(p);
 	}
 
-    private boolean isEncroached(@NotNull final E segment) {
+	private boolean isEncroached(@NotNull final E segment) {
+		E seg = getMesh().isBoundary(segment) ? getMesh().getTwin(segment) : segment;
+		VPoint p1 = getMesh().toPoint(getMesh().getNext(seg));
+		if(isEncroached(seg, p1)) {
+			return true;
+		} else if(getMesh().isAtBoundary(seg)) {
+			return false;
+		} else {
+			VPoint p2 = getMesh().toPoint(getMesh().getNext(getMesh().getTwin(seg)));
+			return isEncroached(seg, p2);
+		}
+	}
+
+    /*private boolean isEncroached(@NotNull final E segment) {
 		E seg = getMesh().isBoundary(segment) ? getMesh().getTwin(segment) : segment;
 	    VLine line = getMesh().toLine(seg);
 	    VPoint midPoint = line.midPoint();
@@ -510,7 +526,7 @@ public class GenRuppertsTriangulator<V extends IVertex, E extends IHalfEdge, F e
 	    }
 
 	    return false;
-    }
+    }*/
 
     // TODO replace this!
 	private boolean isEncroachedExpensive(@NotNull final E segment) {

VadereMeshing/src/org/vadere/meshing/mesh/triangulation/triangulator/impl/PRuppertsTriangulator.java

@@ -20,6 +20,15 @@ public class PRuppertsTriangulator extends GenRuppertsTriangulator<PVertex, PHal
 		super(() -> new PMesh(), pslg, minAngle, circumRadiusFunc, true);
 	}
 
+	public PRuppertsTriangulator(
+			@NotNull final PSLG pslg,
+			@NotNull final Function<IPoint, Double> circumRadiusFunc,
+			final double minAngle,
+			final boolean createHoles) {
+		super(() -> new PMesh(), pslg, minAngle, circumRadiusFunc, createHoles);
+	}
+
+
 	public PRuppertsTriangulator(
 			@NotNull final PSLG pslg,
 			final double minAngle) {