/// <summary>
/// Parses a polygon node, which is a vertex list. Each vertex's
/// position is referenced by its vertex ID to the primitive's master list.
/// Texture coordinates and lightmap coordinates are picked up here,
/// as well as triangulation. Polys are added to a primitive grouped by
/// their material ID so they can be split up later into multiple meshes.
/// </summary>
/// <param name="xmlNode">Xml Poly node</param>
/// <param name="dxsPrim">Dxs Primitive this polygon belongs to</param>
private void ParsePolygon(XmlNode xmlNode, DxsPrimitive dxsPrim)
{
//Parse attributes
int mid = int.Parse(xmlNode.Attributes["mid"].Value);
int count = xmlNode.ChildNodes.Count;
DxsPoly poly = new DxsPoly(mid);
//Add the material to the primitive - if its a newly encountered material
if (materialList.ContainsKey(mid))
{
dxsPrim.AddMaterial(materialList[mid]);
}
//Now go through each vertex and parse it
for (int i = count - 1; i >= 0; i--)
{
// for(int i = 0; i < count; i++) {
XmlNode vertex = xmlNode.ChildNodes[i];
ParseVertex(vertex, dxsPrim, poly);
}
//Either triangulate the polygon, or simply add it if its already a triangle
if (count > 3)
{
TriangulatePolygon(dxsPrim, poly);
}
else
{
poly.ComputeFaceNormal();
dxsPrim.AddPoly(poly);
}
}
/// <summary>
/// Uses the first vertex in a polygon as a pivot to triangulate the polygon,
/// which get added to the dxs primitive.
/// </summary>
/// <param name="dxsPrim">Dxs Primitive the poly belongs to</param>
/// <param name="dxsPoly">Dxs Poly to be triangulated</param>
private void TriangulatePolygon(DxsPrimitive dxsPrim, DxsPoly dxsPoly)
{
DxsVertex[] vertices = dxsPoly.Vertices.ToArray();
DxsVertex v0 = vertices[0];
//Use the first vertex as a pivot and create triangles.
for (int v = 1; v < vertices.Length - 1; v++)
{
DxsPoly poly = new DxsPoly(dxsPoly.MaterialID);
poly.Vertices.Add(v0);
poly.Vertices.Add(vertices[v]);
poly.Vertices.Add(vertices[v + 1]);
poly.ComputeFaceNormal();
dxsPrim.AddPoly(poly);
}
}