A combined object is a combination of sub-objects, i.e., any object type explained until now (Sphere, Ellipsoid, Box …). Objects can be combined by adding different objects together, or by subtracting an object from another one.

In the General 1 tab, standard objects can be added to the combined type, or subtracted from the combined type. Upon startup, a Combined Object consists of a single sphere, which can be removed by deleting Object No. 1 using the Delete button.

It is important to distinguish between Delete and Subtract. While Delete removes an object from the list of objects, Subtract subtracts the defined object from an added object. With this, it is for example possible to create a cylindrical hole through a sphere by adding a Sphere and subtracting a ShortCircularFiber as shown in the example below.

For each object that is created here (by clicking Create), a new tab widget will appear, where the tab header states the object number, the type name, and if the object is added or subtracted.

In the General 2 tab, the position of the Center of the new object can be defined and the main orientation vector can be defined through the Direction vector.

Center, Scaling Factor, Direction, and Perpendicular set up a local coordinate system for the object. Center (called Position in the GAD file) is the origin of the local coordinate system, Direction (Axis1 in the GAD file) is the x-axis and Perpendicular (Axis2) the y-axis, whose position can be freely chosen in a plane by setting the Rotation about Direction.

The z-axis is then already automatically defined as the cross product of the two other axes, such that a right hand system is formed. The ScalingFactor sets the relation between object sizes in the local object coordinates and the global Euclidean coordinate system. A Scaling Factor of 2 means that objects will appear twice as large as given in the local coordinate system.

All coordinates entered in the Object tabs will use this local coordinate system.

The standard objects that create the combined object are defined in the subsequent tabs.

In the GAD file, the number of sub-objects is given by the value after the key NumberOfSubObjects.

Each sub-object has the additional key Operation with the value add or subtract, with Operation add being the default. The operation specifies if a sub-object is added or subtracted from the geometry of the combined object.

In the example above, three cylinders form a 3D cross as a new object type.

As already mentioned above, the coordinates entered in these tabs refer to the local coordinate system of the object, not the global coordinates of the domain.

Besides the possibility to add standard objects to a new combination, subtract allows to cut away parts of an object. Using a combined object with a ShortCircularFiber subtracted from a Sphere results in the following shape: