public void CutEar() { RegionPolygon polygon = new RegionPolygon(m_aUpdatedPolygonVertices); bool bFinish = false; //if (polygon.GetPolygonType()==PolygonType.Convex) //don't have to cut ear // bFinish=true; if (m_aUpdatedPolygonVertices.Length == 3) //triangle, don't have to cut ear { bFinish = true; } LatLng pt = new LatLng(); while (bFinish == false) //UpdatedPolygon { int i = 0; bool bNotFound = true; while (bNotFound && (i < m_aUpdatedPolygonVertices.Length)) //loop till find an ear { pt = m_aUpdatedPolygonVertices[i]; if (IsEarOfUpdatedPolygon(pt)) { bNotFound = false; //got one, pt is an ear } else { i++; } } //bNotFount //An ear found:} if (pt != null) { UpdatePolygonVertices(pt); } polygon = new RegionPolygon(m_aUpdatedPolygonVertices); //if ((polygon.GetPolygonType()==PolygonType.Convex) // && (m_aUpdatedPolygonVertices.Length==3)) if (m_aUpdatedPolygonVertices.Length == 3) { bFinish = true; } } //bFinish=false SetPolygons(); }
/**************************************************************** * To check whether the Vertex is an ear or not based updated Polygon vertices * * ref. www-cgrl.cs.mcgill.ca/~godfried/teaching/cg-projects/97/Ian * /algorithm1.html * * If it is an ear, return true, * If it is not an ear, return false; *****************************************************************/ private bool IsEarOfUpdatedPolygon(LatLng vertex) { RegionPolygon polygon = new RegionPolygon(m_aUpdatedPolygonVertices); if (polygon.Vertices.PolygonVertex(vertex)) { bool bEar = true; if (polygon.Vertices.PolygonVertexType(vertex) == PolygonType.Convex) { LatLng pi = vertex; LatLng pj = polygon.Vertices.PreviousPoint(vertex); //previous vertex LatLng pk = polygon.Vertices.NextPoint(vertex); //next vertex for (int i = m_aUpdatedPolygonVertices.GetLowerBound(0); i < m_aUpdatedPolygonVertices.GetUpperBound(0); i++) { LatLng pt = m_aUpdatedPolygonVertices[i]; if (!(pt.EqualsPoint(pi) || pt.EqualsPoint(pj) || pt.EqualsPoint(pk))) { if (TriangleContainsPoint(new LatLng[] { pj, pi, pk }, pt)) { bEar = false; } } } } //ThePolygon.getVertexType(Vertex)=ConvexPt else //concave point { bEar = false; //not an ear/ } return(bEar); } else //not a polygon vertex; { System.Diagnostics.Trace.WriteLine("IsEarOfUpdatedPolygon: " + "Not a polygon vertex"); return(false); } }
/******************************************************** * To update m_aUpdatedPolygonVertices: * Take out Vertex from m_aUpdatedPolygonVertices array, add 3 points * to the m_aEars **********************************************************/ private void UpdatePolygonVertices(LatLng vertex) { ArrayList alTempPts = new ArrayList(); for (int i = 0; i < m_aUpdatedPolygonVertices.Length; i++) { if (vertex.EqualsPoint( m_aUpdatedPolygonVertices[i])) //add 3 pts to FEars { RegionPolygon polygon = new RegionPolygon(m_aUpdatedPolygonVertices); LatLng pti = vertex; LatLng ptj = polygon.Vertices.PreviousPoint(vertex); //previous point LatLng ptk = polygon.Vertices.NextPoint(vertex); //next point LatLng[] aEar = new LatLng[3]; //3 vertices of each ear aEar[0] = ptj; aEar[1] = pti; aEar[2] = ptk; m_alEars.Add(aEar); } else { alTempPts.Add(m_aUpdatedPolygonVertices[i]); } //not equal points } if (m_aUpdatedPolygonVertices.Length - alTempPts.Count == 1) { int nLength = m_aUpdatedPolygonVertices.Length; m_aUpdatedPolygonVertices = new LatLng[nLength - 1]; for (int i = 0; i < alTempPts.Count; i++) { m_aUpdatedPolygonVertices[i] = (LatLng)alTempPts[i]; } } }