/// <summary>
/// Compute the Facet Normal between three vertices in space. The direction is given by rhs-rule
/// v1v2 x v1v3
/// </summary>
/// <param name="v1"></param>
/// <param name="v2"></param>
/// <param name="v3"></param>
/// <returns></returns>
public static Vector3 CalcFacetNormal(Vertex v1, Vertex v2, Vertex v3)
{
var M = new Vector3(v2.X - v1.X, v2.Y - v1.Y, v2.Z - v1.Z);
var N = new Vector3(v3.X - v1.X, v3.Y - v1.Y, v3.Z - v1.Z);
var normalVector = M.CrossProduct(N);
normalVector.Normalize();
return normalVector;
}
/// <summary>
/// Generates a cartesian mesh by inserting relative X and Y coordinates based on the given distance
/// and Z (elevation) based on a locations map.
/// </summary>
/// <param name="locations">Location data containing elevation information</param>
/// <param name="ni">Number of horizontal (X) grid cells</param>
/// <param name="nj">Number of vertical (Y) grid cells</param>
/// <param name="distEW">Total horizontal distance</param>
/// <param name="distSN">Total vertical distance</param>
/// <returns></returns>
private static Vertex[,] GenerateVerticesMatrix(ref LatLonAlt[,] locations, int ni, int nj, double distEW, double distSN)
{
var x0 = -distEW / 2F;
var y0 = -distSN / 2F;
var y = y0;
double dx = distEW / (double)ni;
double dy = distSN / (double)nj;
var vertices = new Vertex[ni, nj];
for (var j = 0; j < nj; j++)
{
var x = x0;
for (var i = 0; i < ni; i++)
{
vertices[i, j] = new Vertex(x, y, locations[i, j].Altitude);
x += dx;
}
y += dy;
}
return vertices;
}
public static Vertex[,] ToVertex(ref LatLonAlt[,] pos)
{
var vertex = new Vertex[pos.GetLength(0), pos.GetLength(1)];
for (var j = 0; j < pos.GetLength(1); j++)
{
for (var i = 0; i < pos.GetLength(1); i++)
{
vertex[i, j] = ToVertex(pos[i, j]);
}
}
return vertex;
}
public static Vertex ToVertex(LatLonAlt pos)
{
var vertex = new Vertex(pos.Latitude, pos.Longitude, pos.Altitude);
return vertex;
}
/// <summary>
/// Constructor
/// </summary>
/// <param name="vertices">A map of structured N*M vertices </param>
public Stereolithography(Vertex[,] vertices)
{
Vertices = vertices;
}
/// <summary>
/// Write the STL facet field.
/// </summary>
/// <param name="writer"></param>
/// <param name="v1">Vertex 1</param>
/// <param name="v2">Vertex 2</param>
/// <param name="v3">Vertex 3</param>
private void WriteFacet(Vertex v1, Vertex v2, Vertex v3)
{
var normal = Geometry.CalcFacetNormal(v1, v2, v3);
writer.WriteLine(String.Format("facet normal {0} {1} {2}", normal.X, normal.Y, normal.Z));
writer.WriteLine("outer loop");
writer.WriteLine(String.Format("vertex {0} {1} {2}", v1.X, v1.Y, v1.Z));
writer.WriteLine(String.Format("vertex {0} {1} {2}", v2.X, v2.Y, v2.Z));
writer.WriteLine(String.Format("vertex {0} {1} {2}", v3.X, v3.Y, v3.Z));
writer.WriteLine("endloop");
writer.WriteLine("endfacet");
}