Tutorial Post 4: Selected and Bookmarked Endpoints.

Tutorial Post 4: Selected and Bookmarked Endpoints.

Many actions (painting, deleting, some constructive methods) are performed on the sets of the endpoints. The selection sub-menu is invoked by sequence of key presses 'QS':

Here you can find options for selecting the endpoints. For example, initially the default (cancelled) clipping box is so large that you can select all the endpoints by pressing 'X'.

The selected endpoints are marked by little x-shaped crosses of the cursor's color:

(Note that the actual number of selected endpoints in the example is 12, since each segment has two endpoints. If many selections are drawn in the same place then we see only one selection mark.)

Some actions (e.g. folding or triangles-triangles intersection) operate on two sets of endpoints simultaneously. Therefore  you can specify a second set of endpoints: bookmarked endpoints. You can change the selected endpoints into bookmarked endpoints by pressing 'B' on the selection sub-menu. The bookmarked endpoints are marked by little squares of the cursor's color:

Each time you bookmark the selected endpoints, the previous bookmarks are cancelled. Note that you can cancel bookmarks by bookmarking the empty set of selected endpoints.