|3.3 Moving and scaling objects|
There are four modes for transforming objects: translate, stretch, rotate, and shear. If you hold the shift key while pressing the left mouse button, the stretch function keeps the aspect ratio of the objects (an operation we call scaling), and the translate function is restricted to horizontal and vertical translations.
Normally, the transformation functions work on the current selection. However, to make it more convenient to move around many different objects, there is an exception: When the mouse button is pressed while the cursor is not near the current selection, but there is some other object close to the cursor, that object is moved, rotated, scaled, or sheared instead.
By default, the rotate function rotates around the center of the bounding box for the selected objects. This behavior can be overridden by specifying an axis system. If an axis system is set, then the origin is used as the center.
The scale, stretch, and shear functions use a corner of the bounding box for the selected objects as the fix-point of the transformation. Again, if an axis system is set, the origin of the system is used instead. In this case, the shear function will use your x-axis as the fixed axis of the shear operation (rather than a horizontal line).
It is often convenient to rotate or scale around a vertex of an object. This is easy to achieve by setting the origin of the axis system to that vertex, using the Snap to vertex function for setting the axis system.