/// <summary>
/// Get the other node of a <see cref="MeshFace"/>, when
/// looking from <paramref name="fromNode"/>.
/// </summary>
public static MeshNode ToNode(this MeshFace face, MeshNode fromNode)
{
if (ReferenceEquals(face.FromNode, fromNode))
{
return(face.ToNode);
}
return(face.FromNode);
}
/// <summary>
/// Get the other element of a <see cref="MeshFace"/>, when
/// looking from <paramref name="element"/>.
/// <para>
/// For boundary faces, null is returned.
/// </para>
/// </summary>
public static MeshElement OtherElement(this MeshFace face, MeshElement element)
{
if (ReferenceEquals(face.LeftElement, element))
{
return(face.RightElement);
}
if (ReferenceEquals(face.RightElement, element))
{
return(face.LeftElement);
}
throw new Exception("element is not part of face");
}
/// <summary>
/// Create and add a face.
/// <para>
/// A face is only "added once", i.e. when two elements share the face, it is found twice,
/// once defined as "toNode"-"fromNode" and once as "fromNode"-"toNode". The second time,
/// the existing face is being reused, and the element is added as the <see cref="MeshFace.RightElement"/>
/// </para>
/// <para>
/// The <see cref="MeshFace"/> is added to the global list of faces, and also to tne nodes list of faces.
/// </para>
/// </summary>
private void AddFace(MeshElement element, MeshNode fromNode, MeshNode toNode)
{
List <MeshFace> fromNodeFaces = fromNode.Faces;
List <MeshFace> toNodeFaces = toNode.Faces;
if (fromNodeFaces.FindIndex(mf => mf.ToNode == toNode) >= 0)
{
throw new Exception(string.Format("Invalid mesh: Double face, from node {0} to node {1}. " +
"Hint: Probably too many nodes was merged into one of the two face nodes." +
"Try decrease node merge tolerance value",
fromNode.Index + 1, toNode.Index + 1));
}
// Try find "reverse face" going from from-node to to-node.
int reverseFaceIndex = toNodeFaces.FindIndex(mf => mf.ToNode == fromNode);
if (reverseFaceIndex >= 0)
{
// Found reverse face, reuse it and add the elment as the RightElement
MeshFace reverseFace = toNodeFaces[reverseFaceIndex];
reverseFace.RightElement = element;
}
else
{
// Found new face, set element as LeftElement and add it to both from-node and to-node
MeshFace meshFace = new MeshFace()
{
FromNode = fromNode,
ToNode = toNode,
LeftElement = element,
};
Faces.Add(meshFace);
fromNodeFaces.Add(meshFace);
toNodeFaces.Add(meshFace);
}
}
/// <summary>
/// Build derived mesh data, especially the <see cref="MeshFace"/> lists.
/// </summary>
public void BuildDerivedData()
{
Faces = new List <MeshFace>();
// Preallocate list of face on all nodes - used in next loop
for (int i = 0; i < Nodes.Count; i++)
{
Nodes[i].Faces = new List <MeshFace>();
}
// Create all faces.
for (int ielmt = 0; ielmt < Elements.Count; ielmt++)
{
MeshElement element = Elements[ielmt];
element.Faces = new List <MeshFace>();
List <MeshNode> elmtNodes = element.Nodes;
for (int j = 0; j < elmtNodes.Count; j++)
{
MeshNode fromNode = elmtNodes[j];
MeshNode toNode = elmtNodes[(j + 1) % elmtNodes.Count];
AddFace(element, fromNode, toNode);
}
}
// Figure out boundary code
for (int i = 0; i < Faces.Count; i++)
{
MeshFace face = Faces[i];
// If the RightElement exists, this face is an internal face
if (face.RightElement != null)
{
continue;
}
// RightElement does not exist, so it is a boundary face.
int fromCode = face.FromNode.Code;
int toCode = face.ToNode.Code;
// True if "invalid" boundary face, then set it as internal face.
bool internalFace = false;
if (fromCode == 0)
{
internalFace = true;
throw new Exception(string.Format("Invalid mesh: Boundary face, from node {0} to node {1} is missing a boundary code on node {0}. " +
"Hint: Modify boundary code for node {0}",
face.FromNode.Index + 1, face.ToNode.Index + 1));
}
if (toCode == 0)
{
internalFace = true;
throw new Exception(string.Format("Invalid mesh: Boundary face, from node {0} to node {1} is missing a boundary code on node {1}. " +
"Hint: Modify boundary code for node {1}",
face.FromNode.Index + 1, face.ToNode.Index + 1));
}
int faceCode;
// Find face code:
// 1) In case any of the nodes is a land node (code value 1) then the
// boundary face is a land face, given boundary code value 1.
// 2) For boundary faces (if both fromNode and toNode have code values larger than 1),
// the face code is the boundary code value of toNode.
if (fromCode == 1 || toCode == 1)
{
faceCode = 1;
}
else
{
faceCode = toCode;
}
if (!internalFace)
{
face.Code = faceCode;
}
}
// Add face to the elements list of faces
for (int i = 0; i < Faces.Count; i++)
{
MeshFace face = Faces[i];
face.LeftElement.Faces.Add(face);
face.RightElement?.Faces.Add(face);
}
}
/// <summary>
/// Build list of face boundaries of <paramref name="mesh"/>
/// </summary>
public static List <MeshBoundary> BuildBoundaryList(MeshData mesh)
{
if (mesh.Faces == null)
{
mesh.BuildDerivedData();
}
// Sort all faces on boundary code
Dictionary <int, List <MeshFace> > bcs = new Dictionary <int, List <MeshFace> >();
for (int i = 0; i < mesh.Faces.Count; i++)
{
MeshFace meshFace = mesh.Faces[i];
if (meshFace.IsBoundaryFace())
{
List <MeshFace> boundaryFaces;
if (!bcs.TryGetValue(meshFace.Code, out boundaryFaces))
{
boundaryFaces = new List <MeshFace>();
bcs.Add(meshFace.Code, boundaryFaces);
}
boundaryFaces.Add(meshFace);
}
}
List <MeshBoundary> boundaries = new List <MeshBoundary>();
// For each boundary code, find segments
foreach (KeyValuePair <int, List <MeshFace> > bfkvp in bcs)
{
int code = bfkvp.Key;
List <MeshFace> faces = bfkvp.Value;
// Sort faces on FromNode index
faces.Sort((f1, f2) => f1.FromNode.Index.CompareTo(f2.FromNode.Index));
// Create searchable array of FromNode indices
int[] fromNodes = faces.Select(f => f.FromNode.Index).ToArray();
// Matching array telling which boundary segment a given face belongs to
int[] faceSegmentIndex = new int[faces.Count];
for (int ii = 0; ii < faceSegmentIndex.Length; ii++)
{
faceSegmentIndex[ii] = -1;
}
// All segments with this boundary code
List <LinkedList <int> > segments = new List <LinkedList <int> >();
// Make sure to visit all faces
for (int i = 0; i < faces.Count; i++)
{
// Check if this face has already been visited.
if (faceSegmentIndex[i] >= 0)
{
continue;
}
// Start new boundary segment with face i
int currentSegmentIndex = segments.Count;
int currentFaceIndex = i;
LinkedList <int> currentSegment = new LinkedList <int>();
// Add current face to segment
currentSegment.AddLast(currentFaceIndex);
faceSegmentIndex[currentFaceIndex] = currentSegmentIndex;
while (true)
{
// Try find next face, which is the face with fromNode matching currentFace.ToNode
MeshFace currentFace = faces[currentFaceIndex];
int nextFaceIndex = Array.BinarySearch(fromNodes, currentFace.ToNode.Index);
if (nextFaceIndex < 0)
{
// No to-node, we are done with this segment
segments.Add(currentSegment);
break;
}
// Check if the next face is already part of a segment
if (faceSegmentIndex[nextFaceIndex] >= 0)
{
if (faceSegmentIndex[nextFaceIndex] == currentSegmentIndex)
{
// Circular boundary - we are done with this segment
segments.Add(currentSegment);
break;
}
// Now: nextSegment is not the same as the currentSection,
// but they should be - move entire current segment to the
// start of the nextFace segment
int nextFaceSegment = faceSegmentIndex[nextFaceIndex];
// Move all from current segment to
LinkedListNode <int> thisSegmentListNode = currentSegment.Last;
while (thisSegmentListNode != null)
{
int faceToMoveIndex = thisSegmentListNode.Value;
segments[nextFaceSegment].AddFirst(faceToMoveIndex);
faceSegmentIndex[faceToMoveIndex] = nextFaceSegment;
thisSegmentListNode = thisSegmentListNode.Previous;
}
break; // Break out of while (true) loop
}
// Make nextFace to currentFace - add it to the list of current segments.
currentFaceIndex = nextFaceIndex;
currentSegment.AddLast(currentFaceIndex);
faceSegmentIndex[currentFaceIndex] = currentSegmentIndex;
}
}
MeshBoundary meshBoundary = new MeshBoundary()
{
Code = code
};
foreach (LinkedList <int> segment in segments)
{
if (segment == null)
{
continue;
}
List <MeshFace> segmentFaces = new List <MeshFace>(segment.Count);
foreach (int currentFace in segment)
{
segmentFaces.Add(faces[currentFace]);
}
meshBoundary.Segments.Add(segmentFaces);
}
boundaries.Add(meshBoundary);
}
boundaries.Sort((mb1, mb2) => mb1.Code.CompareTo(mb2.Code));
return(boundaries);
}
/// <summary>
/// Add a target, by specifying its (x,y) coordinate.
/// </summary>
public void AddTarget(double x, double y)
{
if (_targets == null)
{
_targets = new List <InterPData>();
}
if (_searcher == null)
{
_searcher = new MeshSearcher(_mesh);
_searcher.SetupElementSearch();
}
InterPData interpData = new InterPData();
// Setting "out-of-bounds" index
interpData.Element1Index = -1;
// Find element that includes the (x,y) coordinate
MeshElement element = _searcher.FindElement(x, y);
// Check if element has been found, i.e. includes the (x,y) point
if (element != null)
{
bool found = false;
interpData.Element1Index = element.Index;
// Check which face the point belongs to, and which "side" of the face
bool isQuad = element.IsQuadrilateral();
int numFaces = isQuad ? 4 : 3;
for (int j = 0; j < numFaces; j++)
{
MeshFace elementFace = element.Faces[j];
// From the element (x,y), looking towards the face,
// figure out wich node is right and which is left.
MeshNode rightNode, leftNode;
if (elementFace.LeftElement == element)
{
rightNode = elementFace.FromNode;
leftNode = elementFace.ToNode;
}
else
{
rightNode = elementFace.ToNode;
leftNode = elementFace.FromNode;
}
// Find also the element on the other side of the face
double otherElementX, otherElementY;
MeshElement otherElement = elementFace.OtherElement(element);
if (otherElement != null)
{
otherElementX = otherElement.XCenter;
otherElementY = otherElement.YCenter;
interpData.Element2Index = otherElement.Index;
}
else
{
// No other element - boundary face, use center of face.
otherElementX = 0.5 * (rightNode.X + leftNode.X);
otherElementY = 0.5 * (rightNode.Y + leftNode.Y);
// Use "itself" as element-2
interpData.Element2Index = element.Index;
}
// Check if point is on the right side of the line between element and other-element
if (MeshExtensions.IsPointInsideLines(x, y, element.XCenter, element.YCenter, rightNode.X, rightNode.Y, otherElementX, otherElementY))
{
(double w1, double w2, double w3) = MeshExtensions.InterpolationWeights(x, y, element.XCenter, element.YCenter, rightNode.X, rightNode.Y, otherElementX, otherElementY);
interpData.NodeIndex = rightNode.Index;
interpData.Element1Weight = w1;
interpData.NodeWeight = w2;
interpData.Element2Weight = w3;
found = true;
break;
}
// Check if point is on the left side of the line between element and other-element
if (MeshExtensions.IsPointInsideLines(x, y, element.XCenter, element.YCenter, otherElementX, otherElementY, leftNode.X, leftNode.Y))
{
(double w1, double w2, double w3) = MeshExtensions.InterpolationWeights(x, y, element.XCenter, element.YCenter, otherElementX, otherElementY, leftNode.X, leftNode.Y);
interpData.NodeIndex = leftNode.Index;
interpData.Element1Weight = w1;
interpData.Element2Weight = w2;
interpData.NodeWeight = w3;
found = true;
break;
}
}
if (!found) // Should never happen, but just in case
{
interpData.Element1Weight = 1;
interpData.Element2Weight = 0;
interpData.NodeWeight = 0;
interpData.Element2Index = element.Index;
interpData.NodeIndex = element.Nodes[0].Index;
}
}
_targets.Add(interpData);
}
/// <summary>
/// Returns true if the face is a boundary face.
/// </summary>
public static bool IsBoundaryFace(this MeshFace face)
{
return(face.RightElement == null);
}