public bool IsCoplanarTo(gEdge edge)
{
// http://mathworld.wolfram.com/Coplanar.html
gVector a = this.Direction;
gVector b = edge.Direction;
gVector c = gVector.ByTwoVertices(this.StartVertex, edge.StartVertex);
return(c.Dot(a.Cross(b)) == 0);
}
public bool OnEdge(gVertex start, gVertex end)
{
if (this.Equals(start) || this.Equals(end))
{
return(true);
}
// https://www.lucidarme.me/check-if-a-point-belongs-on-a-line-segment/
gVector startEnd = gVector.ByTwoVertices(start, end);
gVector startMid = gVector.ByTwoVertices(start, this);
gVector endMid = gVector.ByTwoVertices(this, end);
if (!startMid.IsParallelTo(endMid))
{
return(false);
} // Not aligned
double dotAC = startEnd.Dot(startMid);
double dotAB = startEnd.Dot(startEnd);
return(0 <= dotAC && dotAC <= dotAB);
}
