public bool Init(IEnumerable <double> globalCoords, ref CoordinateSystem CoordinateTranslation, double tolerance, int ptIndexOffset = 0)
{
var essential = globalCoords.Essential();
var origPts = new List <Point3D>();
for (var i = 0; i < essential.Length; i += 3)
{
origPts.Add(new Point3D(essential[i], essential[i + 1], essential[i + 2]));
}
if (CoordinateTranslation == null)
{
//Create plane
var plane = Plane.FromPoints(origPts[0], origPts[1], origPts[2]);
var normal = plane.Normal;
var origin = origPts[0];
var xDir = origPts[0].VectorTo(origPts[1]).Normalize();
var yDir = normal.CrossProduct(xDir);
//The CoordinateSystem class in MathNet.Spatial and its methods aren't not very intuitive as discussed in https://github.com/mathnet/mathnet-spatial/issues/53
//Since I don't understand the offsets that seem to be applied by TransformFrom and TransformTo, I focussed on the Transform method,
//which transforms a local point to a global point.
//In order to transform a point from global into local, the coordinate system needs to be reversed so that the resulting coordinateSystem.Transform does the
//transformation from global to local.
CoordinateTranslation = new CoordinateSystem(new CoordinateSystem(origin, xDir, yDir, normal).Inverse());
}
else
{
this.CoordinateTranslation = CoordinateTranslation;
}
//project points onto the plane - if the points are co-planar and translation is done correctly, all Z values should be zero
var nonCoPlanarPts = 0;
var n = origPts.Count();
for (var i = 0; i < n; i++)
{
var projectedPt = CoordinateTranslation.Transform(origPts[i]);
if (Math.Abs(projectedPt.Z) > tolerance)
{
nonCoPlanarPts++;
}
var localPt = new Point2D(projectedPt.X, projectedPt.Y);
Vertices.Add(new Vertex(ptIndexOffset + i, localPt, origPts[i]));
}
WindingDirection = 0;
IndexedLines = new Dictionary <IndexPair, Line2D>();
if (nonCoPlanarPts > 0)
{
return(false);
}
for (var i = 0; i < n; i++)
{
var indexPair = new IndexPair(ptIndexOffset + i, ptIndexOffset + (i == n - 1 ? 0 : i + 1));
IndexedLines.Add(indexPair, new Line2D(MeshPointByIndex(indexPair.Indices[0]).Local, MeshPointByIndex(indexPair.Indices[1]).Local));
}
WindingDirection = Vertices.Select(mp => mp.Local).GetWindingDirection();
return(true);
}