Introduced TriangleFan class

MeshModel/src/main/java/cz/fidentis/analyst/mesh/core/TriangleFan.java

+package cz.fidentis.analyst.mesh.core;
+
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * 1-ring neighborhood of a given mesh point. The neighborhood consists of 
+ * a ring of vertices forming triangles around the given central point.
+ * 
+ * @author Radek Oslejsek
+ */
+public class TriangleFan {
+    
+    private final List<Integer> vertices = new LinkedList<>();
+    private final List<Integer> triangles = new LinkedList<>();
+    
+    public TriangleFan(MeshFacet facet, int vert) {
+        if (facet == null) {
+            throw new IllegalArgumentException("facet");
+        }
+        
+        //System.out.println(facet.getVertices());
+        
+        CornerTable ct = facet.getCornerTable();
+        
+        int vertRow = getVertexRow(ct, vert);
+        //System.out.println("DDD " + vert + " " + vertRow + " " + ct.getRow(vertRow).getVertexIndex());
+        if (vertRow == -1) {
+            throw new IllegalArgumentException("vert");
+        }
+        
+        computeOneRingData(ct, vertRow, vertices, triangles);
+    }
+    
+    public boolean isEnclosed() {
+        return Objects.equals(vertices.get(0), vertices.get(vertices.size()-1));
+    }
+    
+    public boolean isBoundery() {
+        return !isEnclosed();
+    }
+    
+    public List<Integer> getVertices() {
+        return Collections.unmodifiableList(vertices);
+    }
+    
+    public List<Integer> getTriangles() {
+        return Collections.unmodifiableList(triangles);
+    }
+    
+    private void computeOneRingData(CornerTable ct, int vertRow, List<Integer> vertices, List<Integer> triangles) {
+        //System.out.println(ct);
+        //System.out.println("AAA " + ct.getRow(vertRow).getVertexIndex());
+        int ringVertRow = ct.getIndexOfNextCornerInFace(vertRow);
+        while (true) {
+            //System.out.println("BBB " + ct.getRow(ringVertRow).getVertexIndex());
+            vertices.add(ct.getRow(ringVertRow).getVertexIndex());
+            if (vertices.size() > 1 && isEnclosed()) {
+                return; // the ring is closed; we are done
+            }
+            //System.out.println("CCC " + ct.getRow(ct.getIndexOfNextCornerInFace(ringVertRow)).getVertexIndex());
+            ringVertRow = ct.getIndexOfOppositeCorner(ct.getIndexOfNextCornerInFace(ringVertRow));
+            if (ringVertRow == -1) {
+                break; // we reached an open end
+            }
+            //System.out.println("DDD " + ct.getRow(ringVertRow).getVertexIndex());
+            triangles.add(ct.getIndexOfFace(ringVertRow));
+        }
+        
+        ringVertRow = ct.getIndexOfPreviousCornerInFace(vertRow);
+        while (true) {
+            vertices.add(0, ct.getRow(ringVertRow).getVertexIndex());
+            if (vertices.size() > 1 && isEnclosed()) {
+                return; // the ring is closed; we are done
+            }
+            ringVertRow = ct.getIndexOfOppositeCorner(ct.getIndexOfPreviousCornerInFace(ringVertRow));
+            if (ringVertRow == -1) {
+                break; // we reached an open end
+            }
+            triangles.add(ct.getIndexOfFace(ringVertRow));
+        }
+    }
+    
+    private int getVertexRow(CornerTable cornerTable, int vert) {
+        for (int i = 0; i < cornerTable.getSize(); i++) {
+            if (cornerTable.getRow(i).getVertexIndex() == vert) {
+                return i;
+            }
+        }
+        return -1;
+    }
+    
+}