Key points and anchor points

All objects have a number of key points, which define the object’s position and size.

These are:

• Lines — at each end and the mid-point.
• Arcs — at each end of the sector, the centre point, and the mid-point.
• Curves — at each point where the curve can change direction.
• Surfaces — at each corner of the surface patch (the key points on the associated curves behave as for curves).
• Workplanes — at the origin and end of each axis pointer.

When the object is selected, the program chooses one of its key points as the object’s anchor point for the current selection. The next selection may use a different key point.

The anchor point is used by the program to decide where to position the object, for example during all types of moves and copies. The rules for which key point is chosen to be the anchor are as follows:

• When a single object is selected, the anchor point is the object’s key point which was nearest the cursor when you selected the object.
• When objects are selected using a rubber box, the anchor point is at the centre of the smallest box capable of containing the objects. This applies whether the rubber box contains one or many objects.
• If objects are shift selected individually, the anchor point for the group is the key point nearest the cursor on the last object selected.

To specify an anchor point for a group:

1. Select a group of objects, using the rubber-band.
2. Press the Control key and deselect the objects.
3. Press the Control key and reselect an object.

   The anchor point for the group selection is on this object rather than at the centre of the rubber band.