/// <summary>
/// Computes a geodesic on a mesh given a starting point and an initial direction.
/// Returns true if successfull and false if something went wrong.
/// </summary>
public static bool StartDir(HE_MeshPoint meshPoint, Vector3d vector, HE_Mesh mesh, int maxIter, out List <Point3d> geodesic)
{
// Get initial face on the mesh
HE_Face initialFace = mesh.Faces[meshPoint.FaceIndex];
// Start iteration
// Create variables for current iteration step
HE_Face thisFace = initialFace;
Point3d thisPoint = new Point3d();
Vector3d thisDirection = vector;
int iter = 0;
List <Point3d> geodPoints = new List <Point3d>();
do
{
Ray ray = new Ray(thisPoint, thisDirection);
// Find intersection between ray and boundary
AR_Lib.Intersect3D.RayFacePerimeter(ray, thisFace, out Point3d nextPoint, out HE_HalfEdge halfEdge);
// Intersection method should check for correct direction using sign of dot product
// Add point to pointlist
geodPoints.Add(nextPoint);
// Walk to next face
HE_Face nextFace = halfEdge.Twin.Face;
// Flip vector to next face
Vector3d perpVector = Vector3d.CrossProduct(thisDirection, HE_MeshGeometry.FaceNormal(thisFace));
Vector3d nextVector = Vector3d.CrossProduct(HE_MeshGeometry.FaceNormal(nextFace), perpVector);
// Assign iteration variables to current
thisPoint = nextPoint;
thisFace = nextFace;
thisDirection = nextVector;
// Increase counter
iter++;
} while (iter < maxIter);
// Assign outputs
geodesic = geodPoints;
return(true);
}
/// <summary>
/// Compute the intersection between a mesh face perimeter and a ray tangent to the face.
/// </summary>
/// <param name="ray">The tangent ray.</param>
/// <param name="Face">The mesh face.</param>
/// <param name="result">The resulting intersection point.</param>
/// <param name="halfEdge">The half-edge on where the intersection lies.</param>
/// <returns></returns>
public static ISRayFacePerimeter RayFacePerimeter(Ray ray, HE_Face Face, out Point3d result, out HE_HalfEdge halfEdge)
{
Vector3d faceNormal = HE_MeshGeometry.FaceNormal(Face);
Vector3d biNormal = Vector3d.CrossProduct(ray.Direction, faceNormal);
Plane perpPlane = new Plane(ray.Origin, ray.Direction, faceNormal, biNormal);
List <HE_Vertex> vertices = Face.adjacentVertices();
Point3d temp = new Point3d();
Line line = new Line(vertices[0], vertices[1]);
if (LinePlane(line, perpPlane, out temp) != ISLinePlane.Point)
{
result = null; halfEdge = null; return(ISRayFacePerimeter.Point);
} // No intersection found
if (temp != ray.Origin && temp != null)
{
result = temp; halfEdge = null; return(ISRayFacePerimeter.Point);
} // Intersection found
line = new Line(vertices[1], vertices[2]);
if (LinePlane(line, perpPlane, out temp) != ISLinePlane.Point)
{
result = null; halfEdge = null; return(ISRayFacePerimeter.NoIntersection);
} // No intersection found
if (temp != ray.Origin && temp != null)
{
result = temp; halfEdge = null; return(ISRayFacePerimeter.Point);
} // Intersection found
line = new Line(vertices[2], vertices[0]);
if (LinePlane(line, perpPlane, out temp) != ISLinePlane.Point)
{
result = null; halfEdge = null; return(ISRayFacePerimeter.NoIntersection);
}
if (temp != ray.Origin && temp != null)
{
result = temp; halfEdge = null; return(ISRayFacePerimeter.Point);
}
else
{
result = null; halfEdge = null; return(ISRayFacePerimeter.Error);
}
}
