                                                                     erase
Chapter 9 Input Modes

Activates the erase mode in the specified eraser shape.

erase

    Activates the erase mode in the specified eraser shape.

         erase [-s] shape

    Activates the graphics input erase mode and an optional -s automatic snap
    capability.  The snap option causes all entered x,y positions to be
    corrected to existing coordinate positions (on pixels) if such existing
    positions can be located within a given radius of the entered location.
    The search radius tolerance value is in the map header file (search_rad
    =).  Use the start command to begin erasing an object and the continue
    command for all subsequent vertices for that object.  Then, use the start
    command to begin erasing a new object.  Note that the current graphics
    input mode/action is displayed in the upper-left window of the LTPlus
    screen.  The draw mode remains active until either another mode is invoked
    or the clear_mode command is executed.
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    Options/arguments:

         -s        Invokes snap mode (optional)
         shape     Shape type descriptor, including:
                   point     (single pixel)
                   line      (pixel unit width sequence)
                   fat_line  (3-pixel width sequence) 
                   rectangle (defined by a pair of x,y positions)
                   wedge     (walking triangle)
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    Example(s):

    To invoke the fat_line erase mode starting with a position defined as x=456
    and y=222, with the snap mode activated, enter:
     
         erase -s fat_line (or erase -s f)
         start 456 222

    To continue the erase -s fat_line mode at a position defined as x=488 and
    y=225, enter:
     
         continue 488 225
     
    To remain in the erase -s fat_line mode while moving, but not erasing, to a
    new position defined as x=500 and y=236, enter:
     
         start 500 236



    To invoke the erase rectangle mode starting at the position defined by
    x=790 and y=345, with snap mode suppressed, enter:
     
         erase rectangle (or erase r)
         start 790 345
     
    To re-position the starting position of the rectangle to x=690 and y=345,
    enter (prior to any continue commands):
     
         start 690 345
     
    To complete the rectangle erasing action to encompass the rectangular area
    bounded by 690,345 and 700,390 (lower-left and upper-right corners....any
    two, diagonally opposed positions will suffice), enter:

         continue 700 390
     
    Note that the erase rectangle command deletes all data (erases on pixels)
    within the defined rectangular area.

    To exit from the erase mode, enter:
     
         clear_mode
     
    or enter a new graphics input mode command.
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    See also:

              clear_mode, continue, draw, start
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