-\anchor occ_background
-<h2>Background</h2>
-
-OCC Viewer background can be customized using the "Change background"
-popup menu command that opens the following dialog box:
-
-\image html change_background_dlg.png
-
-The following types of the background are supported:
-
-- Single color: the background is colored with the solid color
- specified by the user in the dialog box.
-
-- Gradient background: the background is gradiently colored according
- to two colors and the gradient type specified in the dialog box. The
- following types of background are supported:
-
- - Horizontal
-
- - Vertical
-
- - First diagonal
-
- - Second diagonal
-
- - First corner
-
- - Second corner
-
- - Third corner
-
- - Fourth corner
-
-- Image: allows to set image as viewer background and define filling type:
-
- - Center: the image is located at the center of the viewer backgound
-
- - Tile: the image fills the entire viewer backgound one by one
-
- - Stretch: the image is stretched to the entire viewer backgound.
-
-Default background for the viewer is specified via the
-\ref occ_preferences "application preferences".
-
-<h2>Polyline selection</h2>
-
-OCC Viewer features a special <b>Polyline Selection</b> mechanism,
-which allows selecting an arbitraty part of the graphic area using a
-polygon frame (rubber band), instead of the usual selection with a
-rectangular frame.
-
-To produce a Polyline Selection, lock the right mouse button and draw
-the first side of the polygon, then change the direction by clicking
-the left mouse button add draw another side, etc. The whole selection
-frame is drawn with the locked right mouse button.
-
-\image html polyselection1.png
-
-As a result, only the nodes within the frame are selected.
-
-\image html polyselection2.png