/// <summary>
/// check whether 2 vectors are parallel
/// </summary>
/// <param name="vec4A">
/// the vector to be checked
/// </param>
/// <param name="vec4B">
/// the vector to be checked
/// </param>
/// <returns>
/// if they're parallel, return true; otherwise false
/// </returns>
private bool IsLinesParallel(Utility.Vector4 vec4A, Utility.Vector4 vec4B)
{
// if 2 vectors are parallel, they should be like the following formula:
// vec4A.X vec4A.Y vec4A.Z
// ------- == ------- == -------
// vec4B.X vec4B.Y vec4B.Z
// change to multiply, it's
// vec4A.X * vec4B.Y == vec4A.Y * vec4B.X &&
// vec4A.Y * vec4B.Z == vec4A.Z * vec4B.Y
double aa = vec4A.X * vec4B.Y;
double bb = vec4A.Y * vec4B.X;
double cc = vec4A.Y * vec4B.Z;
double dd = vec4A.Z * vec4B.Y;
double ee = vec4A.X * vec4B.Z;
double ff = vec4A.Z * vec4B.X;
const double tolerance = 0.0001d;
if (Math.Abs(aa - bb) < tolerance &&
Math.Abs(cc - dd) < tolerance &&
Math.Abs(ee - ff) < tolerance)
{
return(true);
}
return(false);
}
/// <summary>
/// compute the cross product of 2 edges
/// </summary>
/// <param name="edgeA">
/// the edge for the cross product
/// </param>
/// <param name="edgeB">
/// the edge for the cross product
/// </param>
/// <returns>
/// the cross product of 2 edges
/// </returns>
private Utility.Vector4 ComputeCrossProduct(Edge edgeA, Edge edgeB)
{
List <XYZ> pointsA = edgeA.Tessellate() as List <XYZ>;
List <XYZ> pointsB = edgeB.Tessellate() as List <XYZ>;
Autodesk.Revit.DB.XYZ vectorA = pointsA[1] - pointsA[0];
Autodesk.Revit.DB.XYZ vectorB = pointsB[1] - pointsB[0];
Utility.Vector4 vec4A = new Utility.Vector4(vectorA);
Utility.Vector4 vec4B = new Utility.Vector4(vectorB);
return(Utility.Vector4.CrossProduct(vec4A, vec4B));
}
/// <summary>
/// check whether 2 edges are parallel
/// </summary>
/// <param name="edgeA">
/// the edge to be checked
/// </param>
/// <param name="edgeB">
/// the edge to be checked
/// </param>
/// <returns>
/// if they're parallel, return true; otherwise false
/// </returns>
private bool IsLinesParallel(Edge edgeA, Edge edgeB)
{
List <XYZ> pointsA = edgeA.Tessellate() as List <XYZ>;
List <XYZ> pointsB = edgeB.Tessellate() as List <XYZ>;
Autodesk.Revit.DB.XYZ vectorA = pointsA[1] - pointsA[0];
Autodesk.Revit.DB.XYZ vectorB = pointsB[1] - pointsB[0];
Utility.Vector4 vec4A = new Utility.Vector4(vectorA);
Utility.Vector4 vec4B = new Utility.Vector4(vectorB);
return(IsLinesParallel(vec4A, vec4B));
}
/// <summary>
/// check whether the faces of the mass are one-one parallel
/// </summary>
/// <param name="faces">
/// the 6 faces of the mass
/// </param>
/// <returns>
/// if the 6 faces are one-one parallel, return true; otherwise false
/// </returns>
private bool IsFacesParallel(FaceArray faces)
{
// step1: get the normals of the 6 faces
List <Utility.Vector4> normals = new List <Utility.Vector4>();
foreach (Face face in faces)
{
EdgeArrayArray edgeArrayArray = face.EdgeLoops;
EdgeArray edges = edgeArrayArray.get_Item(0);
if (null == edges ||
2 > edges.Size)
{
return(false);
}
// we use the cross product of 2 non-parallel vectors as the normal
for (int i = 0; i < edges.Size - 1; i++)
{
Edge edgeA = edges.get_Item(i);
Edge edgeB = edges.get_Item(i + 1);
// if edgeA & edgeB are parallel, can't compute the cross product
bool isLinesParallel = IsLinesParallel(edgeA, edgeB);
if (true == isLinesParallel)
{
continue;
}
Utility.Vector4 vec4 = ComputeCrossProduct(edgeA, edgeB);
normals.Add(vec4);
break;
}
}
// step 2: the 6 normals should be one-one parallel pairs
if (null == normals ||
6 != normals.Count)
{
return(false);
}
bool[] matchedList = new bool[6];
for (int i = 0; i < matchedList.Length; i++)
{
matchedList[i] = false;
}
// check whether the normal has another matched parallel normal
for (int i = 0; i < matchedList.Length; i++)
{
if (true == matchedList[i])
{
continue;
}
Utility.Vector4 vec4A = normals[i];
for (int j = 0; j < matchedList.Length; j++)
{
if (j == i ||
true == matchedList[j])
{
continue;
}
Utility.Vector4 vec4B = normals[j];
if (true == IsLinesParallel(vec4A, vec4B))
{
matchedList[i] = true;
matchedList[j] = true;
break;
}
}
}
// step 3: check each of the 6 normals has matched parallel normal
for (int i = 0; i < matchedList.Length; i++)
{
if (false == matchedList[i])
{
return(false);
}
}
// all the normals have matched parallel normals
return(true);
}
/// <summary>
/// check whether 2 edges are parallel
/// </summary>
/// <param name="edgeA">
/// the edge to be checked
/// </param>
/// <param name="edgeB">
/// the edge to be checked
/// </param>
/// <returns>
/// if they're parallel, return true; otherwise false
/// </returns>
private bool IsLinesParallel(Edge edgeA, Edge edgeB)
{
List<XYZ> pointsA = edgeA.Tessellate() as List<XYZ>;
List<XYZ> pointsB = edgeB.Tessellate() as List<XYZ>;
Autodesk.Revit.DB.XYZ vectorA = pointsA[1] - pointsA[0];
Autodesk.Revit.DB.XYZ vectorB = pointsB[1] - pointsB[0];
Utility.Vector4 vec4A = new Utility.Vector4(vectorA);
Utility.Vector4 vec4B = new Utility.Vector4(vectorB);
return IsLinesParallel(vec4A, vec4B);
}
/// <summary>
/// compute the cross product of 2 edges
/// </summary>
/// <param name="edgeA">
/// the edge for the cross product
/// </param>
/// <param name="edgeB">
/// the edge for the cross product
/// </param>
/// <returns>
/// the cross product of 2 edges
/// </returns>
private Utility.Vector4 ComputeCrossProduct(Edge edgeA, Edge edgeB)
{
List<XYZ> pointsA = edgeA.Tessellate() as List<XYZ>;
List<XYZ> pointsB = edgeB.Tessellate() as List<XYZ>;
Autodesk.Revit.DB.XYZ vectorA = pointsA[1] - pointsA[0];
Autodesk.Revit.DB.XYZ vectorB = pointsB[1] - pointsB[0];
Utility.Vector4 vec4A = new Utility.Vector4(vectorA);
Utility.Vector4 vec4B = new Utility.Vector4(vectorB);
return Utility.Vector4.CrossProduct(vec4A, vec4B);
}
