At a point prompt with a base point, holding Shift turns ortho on when
ORTHOMODE is off and off when it is on; releasing it restores the setting.
ORTHOMODE itself is never changed. While the override turns ortho on, polar
tracking is off, as with ortho on.
The UI already passed the Shift state to Session::snap_cursor (for POLARMODE
bit 8's Shift to acquire), so the change is in the engine only: snap_cursor
applies the override to its copy of the settings. Window corners (ZOOM
Window) and prompts without a base point are unaffected.
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>
Resting the cursor on a snap point acquires it for tracking (seven at
most; resting again releases it). Acquired points send horizontal and
vertical alignment paths, or every polar angle with POLARMODE 2; the
cursor snaps where two paths cross, where a path crosses an object, or
onto the nearest path. EXT runs a line or arc on from an acquired end,
PAR gives a path parallel to a rested-on line through the base point,
APP snaps where objects would meet if extended. Direct distance entry
follows the path the cursor is on. POLARMODE is now AutoCAD's bitcode;
POLARADDANG and AUTOSNAP are new.
The engine owns all of it (Session::snap_cursor, snap/tracking.rs); the
canvas draws the + markers, dotted paths and tooltip.
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
