The Pack UVs tool automates the process of organizing UV island data to fit into the standard 0 to 1 UV space. The command includes options for Pack, Stretch and Orient as well as a Gaps percentage setting. The command could be thought of as an automated puzzle solver. With the default settings the command will move, scale and rotate each individual UV island until they all fit neatly within the 0 to 1 UV grid space, as if solving a complex jigsaw puzzle.
Usage
The 'Pack UVs' command option is found in the menu bar under "Texture > UV Operators > Pack". The command will modify the currently selected UV map in the Lists viewport, or the first one selected in the case of multiple selections. Invoking the command opens the above dialog with user controllable options-
Pack: This options controls if the UV islands can be moved from their current location.
Stretch: This option controls whether pieces are kept rigid or if they can be stretched (distorted) for a better fit.
Orient: This option controls if the UV islands can be rotated as they are packed.
Direction: The 'Direction' control offers three options for controlling the main orientation of the UV islands, 'AUTO' will orient them in the direction that best fits, 'HORIZONTAL' will orient UV islands mostly wide and 'VERTICAL' will orient them mostly tall.
Gaps: The 'Gaps' options controls the final spacing between the islands.
Based on Bounding Box: This toggle, when enabled, will treat each island as a rectangular shape, based on the overall width and height.
Lock Stacked: This toggle, when enabled, will keep stacked islands intact when packing. Overlapping islands must share vertex positions, such as when UV mapped geometry is copied, pasted and moved in the 3D viewport or half of a model is mirrored for symmetry.
