private static void SaveNavMeshLinks(NavMesh navMesh, int indentLevel, StringBuilder xmlData)
{
xmlData.AppendLine(new string('\t', indentLevel) + "<links>");
{
indentLevel++;
foreach (var link in navMesh.Links)
{
xmlData.AppendLine(new string('\t', indentLevel) + "<link>");
{
indentLevel++;
xmlData.AppendFormat(new string('\t', indentLevel) +
"<start polygon=\"{0}\" edgestart=\"{1}\" edgeend=\"{2}\"/>\n",
FindPolygonIndex(navMesh, link.StartPoly),
link.StartEdgeIndex.Start,
link.StartEdgeIndex.End);
xmlData.AppendFormat(new string('\t', indentLevel) +
"<end polygon=\"{0}\" edgestart=\"{1}\" edgeend=\"{2}\"/>\n",
FindPolygonIndex(navMesh, link.EndPoly),
link.EndEdgeIndex.Start,
link.EndEdgeIndex.End);
indentLevel--;
}
xmlData.AppendLine(new string('\t', indentLevel) + "</link>");
}
indentLevel--;
}
xmlData.AppendLine(new string('\t', indentLevel) + "</links>");
}
/// <summary>
/// Works out a graph of nodes on top of the navmesh.
/// Each polygon is a node and a node is added a connecting edges of linked polygons.
/// The node graph class member is filled in by running this method.
/// It's quite likely this code isn't very optimal.
/// </summary>
/// <param name="polyStart">The polygon the entity is currently in.</param>
/// <param name="polyEnd">The polygon the entity would like to be in.</param>
/// <param name="from">The point in the entity is current positioned.</param>
/// <param name="to">The point the entity would like to be positioned.</param>
/// <param name="navMesh">The navigation mesh describing the polygons and their links.</param>
/// <returns>The start and end nodes for the journey the player wants to take</returns>
private Tuple<NavigationNode, NavigationNode> CreateNodeNetwork(ConvexPolygon polyStart, ConvexPolygon polyEnd, Point from, Point to, NavMesh navMesh)
{
_nodeGraph.Clear();
// Store a map poly -> node to make it simple to work out the connection nodes.
Dictionary<ConvexPolygon, NavigationNode> polyToNodeMap = new Dictionary<ConvexPolygon, NavigationNode>();
NavigationNode startNode = null;
NavigationNode endNode = null;
// Create a node for the centroid of each polygon
// Replace the postion of the start and end polygon.
foreach (ConvexPolygon polygon in navMesh.PolygonList)
{
Point position;
NavigationNode node;
if (polyStart == polygon)
{
position = from;
node = new NavigationNode(position);
startNode = node;
}
else if (polyEnd == polygon)
{
position = to;
node = new NavigationNode(position);
endNode = node;
}
else
{
position = polygon.CalculateCentroid();
node = new NavigationNode(position);
}
_nodeGraph.Add(node);
polyToNodeMap.Add(polygon, node);
}
// Create the edge nodes and add the links
// !* This is where you'd add several nodes per edge, if you wanted.
foreach (PolygonLink link in navMesh.Links)
{
LineSegment line = link.GetShortestEdge();
Point midPoint = line.GetMiddle();
NavigationNode connectionNode = new NavigationNode(midPoint);
// Add bidirectional links to connected polys and edge polys.
polyToNodeMap[link.StartPoly].Neighbours.Add(connectionNode);
connectionNode.Neighbours.Add(polyToNodeMap[link.StartPoly]);
polyToNodeMap[link.EndPoly].Neighbours.Add(connectionNode);
connectionNode.Neighbours.Add(polyToNodeMap[link.EndPoly]);
_nodeGraph.Add(connectionNode);
}
return new Tuple<NavigationNode, NavigationNode>(startNode, endNode);
}
public List<Point> GetPath(Point from, Point to, NavMesh navMesh)
{
List<Point> path = new List<Point>();
// First find the polygon they're in
// !* May want a little overlapping so all screen can be clicked.
// In that case this should check if all intersected options contain as same poly start/end
ConvexPolygon polyStart = navMesh.PolygonList.First(x => x.Intersects(from));
ConvexPolygon polyEnd = navMesh.PolygonList.First(x => x.Intersects(to));
if (polyStart == null || polyEnd == null)
{
return path;
}
else if (polyStart == polyEnd)
{
path.Add(from);
path.Add(to);
}
else if (polyStart != polyEnd)
{
// This does not need doing every time but it's easier to code if is recreated.
_astar = new AStar<NavigationNode>(
delegate(NavigationNode startNode, NavigationNode endNode)
{
return Math.Sqrt(startNode.Position.X * endNode.Position.X
+ startNode.Position.Y * endNode.Position.Y);
});
var startEndNodes = CreateNodeNetwork(polyStart, polyEnd, from, to, navMesh);
_astar.FindPath(startEndNodes.Item1, startEndNodes.Item2);
_astar.Path.Reverse();
foreach (var node in _astar.Path)
{
path.Add(node.Position);
}
}
return path;
}
private static int FindPolygonIndex(NavMesh navMesh, ConvexPolygon convexPolygon)
{
return navMesh.PolygonList.FindIndex(convexPolygon.Equals);
}
private static void LoadSinglePolygon(XmlTextReader xmlReader, NavMesh navMesh)
{
ConvexPolygon polygon = new ConvexPolygon();
xmlReader.MoveToContent();
while (xmlReader.Read())
{
if ("point" == xmlReader.Name)
{
float x = float.Parse(xmlReader.GetAttribute("x"));
float y = float.Parse(xmlReader.GetAttribute("y"));
polygon.Vertices.Add(new Point(x, y));
}
else if("polygon" == xmlReader.Name)
{
polygon.GenerateEdges();
navMesh.AddPolygon(polygon);
return;
}
}
}
private static void LoadPolygons(XmlTextReader xmlReader, NavMesh navMesh)
{
xmlReader.MoveToContent();
while (xmlReader.Read())
{
if ("polygon" == xmlReader.Name)
{
LoadSinglePolygon(xmlReader, navMesh);
}
else if ("polygons" == xmlReader.Name)
{
return;
}
}
}
/// <summary>
/// This function will look up the polygon index right away.
/// This could potentially cause problems if the XML has the polygon defs later in the file.
/// The values should really be cached and it should be done after.
/// (or thrown in a closure but the C# syntax is a little too messy for that)
/// </summary>
/// <param name="xmlReader"></param>
/// <param name="navMesh"></param>
private static void LoadSingleLink(XmlTextReader xmlReader, NavMesh navMesh)
{
int startPolygonIndex = -1;
int startEdgeStart = -1;
int startEdgeEnd = -1;
int endPolygonIndex = -1;
int endEdgeStart = -1;
int endEdgeEnd = -1;
xmlReader.MoveToContent();
while (xmlReader.Read())
{
if ("start" == xmlReader.Name)
{
startPolygonIndex = int.Parse(xmlReader.GetAttribute("polygon"));
startEdgeStart = int.Parse(xmlReader.GetAttribute("edgestart"));
startEdgeEnd = int.Parse(xmlReader.GetAttribute("edgeend"));
}
else if ("end" == xmlReader.Name)
{
endPolygonIndex = int.Parse(xmlReader.GetAttribute("polygon"));
endEdgeStart = int.Parse(xmlReader.GetAttribute("edgestart"));
endEdgeEnd = int.Parse(xmlReader.GetAttribute("edgeend"));
}
else if ("link" == xmlReader.Name)
{
PolygonLink polygonLink = new PolygonLink(
navMesh.PolygonList[startPolygonIndex],
new IndexedEdge(startEdgeStart, startEdgeEnd),
navMesh.PolygonList[endPolygonIndex],
new IndexedEdge(endEdgeStart, endEdgeEnd));
navMesh.AddLink(polygonLink);
return;
}
}
}
private static void LoadLinks(XmlTextReader xmlReader, NavMesh navMesh)
{
xmlReader.MoveToContent();
while (xmlReader.Read())
{
if ("link" == xmlReader.Name)
{
LoadSingleLink(xmlReader, navMesh);
}
else if ("links" == xmlReader.Name)
{
return;
}
}
}
private static void SaveNavMeshPolygons(NavMesh navMesh, int indentLevel, StringBuilder xmlData)
{
xmlData.AppendLine(new string('\t', indentLevel) + "<polygons>");
{
indentLevel++;
foreach (ConvexPolygon polygon in navMesh.PolygonList)
{
xmlData.AppendLine(new string('\t', indentLevel) + "<polygon>");
{
indentLevel++;
foreach (Point point in polygon.Vertices)
{
xmlData.AppendFormat(new string('\t', indentLevel) +
"<point x=\"{0}\" y =\"{1}\"/>",
point.X, point.Y);
}
indentLevel--;
}
xmlData.AppendLine(new string('\t', indentLevel) + "</polygon>");
}
indentLevel--;
}
xmlData.AppendLine(new string('\t', indentLevel) + "</polygons>");
}
private void RenderNavMesh(NavMesh navMesh)
{
GLUtil.SetColor(new Color(0f, 0f, 1.0f, 0.5f));
navMesh.PolygonList.ForEach(x => GLUtil.RenderPolygonFilled(x));
GLUtil.SetColor(new Color(0.5f, 0.1f, 0.1f, 1f));
navMesh.PolygonList.ForEach(x => GLUtil.RenderPolygon(x));
}
public AddPolygonState(Input input, NavMesh navMesh)
{
_input = input;
_navMesh = navMesh;
}
public DefaultEditState(Input input, NavMesh navMesh)
{
_input = input;
_navMesh = navMesh;
}
public AddLinkState(Input input, NavMesh navMesh)
{
_input = input;
_navMesh = navMesh;
}
public AddVertexState(Input input, NavMesh navMesh)
{
_input = input;
_navMesh = navMesh;
}