A trihedron is a geometric entity which defines a local coordinate system. It can be used to reposition the mesh in another frame using the Geometry/Mesh Operators. It can be be used for shape optimization
ShapeValueExtractor (see Fonctions Objectives), where the shape of a meshed entity in a given frame is compared with respect to a desired geometry in another frame.
A trihedron is defined by 3 points
pt2, which are not on a a same line.
pt0 is the origin. The line
pt1 is the direction of the first axis, (local
x axis). The third direction (local
z axis) is defined by the cross product of the directions
pt2. Finally, the second direction, (local
y axis), is defined by the cross product of the local vectors
z. Syntactically, it is written:
pt0 = Point(0, x0, y0, z0) pt1 = Point(1, x1, y1, z1) pt2 = Point(2, x2, y2, z2) triedre1 = Triedre(pt0, pt1, pt2)
As for the
Axes, points can also be defined in the
pointsetor in the
triedre1 = Triedre(pointset(1), pointset(2), pointset(3)) triedre2 = Triedre(meshpointset(1), meshpointset(2), meshpointset(3))
In this case, the trihedron will move if the points are moving.