Tham khảo tài liệu 'beginning autocad 2002 episode 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Drawing erasing and the selection set 23 11 From the Draw toolbar activate the CIRCLE icon and prompt _circle Specify center point for circle or 3P 2P Ttr tan tan radius and Active Assistance for circle displayed - Fig. b respond pick any point on the screen as the circle centre prompt Specify radius of circle or Diameter respond drag out the circle and pick any point for radius. 12 From the menu bar select Draw-Circle-Center Radius and pick a centre point and drag out a radius. 13 At the command prompt enter CIRCLE R and create another circle anywhere on the screen. 14 Using the icons menu bar or keyboard entry draw some more lines and circles until you are satisfied that you can activate and end the two commands. 15 Figure a displays some line and circle objects. b Selecting individual objects for erasing. The objects picked are highlighted and right-click or R will erase them. c Using a WINDOW selection for erasing. Only those objects which are COMPLETELY within the window boundary will be erased. d Using a CROSSING selection for erasing. All objects WITHIN and which CROSS the boundary will be erased. Figs b c and d demonstrate how objects can be erased by 1. individual object selection - fig b 2. selection using a window - fig c 3. selection using a crossing fig d The window crossing effects are extensively used with other Modify commands. Figure Drawing and erasing line and circle objects. 24 Beginning AutoCAD 2002 Blips Several users may have small crosses at the end of the lines drawn on the screen and at the circle centre points. These crosses are called BLIPS and are used to identify the start and end point of lines circle centres etc. The are NOT OBJECTS ENTITIES and will not be plotted out on a final drawing. Personally I find them a nuisance and always turn them off. This can be achieved by entering BLIPMODE R at the command line and prompt Enter mode ON OFF enter OFF R If you do not want to turn the blips off then by selecting from the menu
