This function provides two options for the user to decide the position
of the section plane: fixed or moved.
1.
FIXED
If the user selects this option, the section cut plane is fixed. The section
line will be made when the model intersects with the fixed section cut plane in
each time step. Due to the relative movement between the model and the fixed
section cut plane, the shape of the section line varies along with the model
movement. Therefore, the section line varies in different time steps.
2. MOVED
If the user selects this option, the section cut plane is moved with
the model. The section cut plane always intersects with the same elements in
the model in different time steps. This will assure that the section line is
always cut from the same elements during the animation.