Object Selection

Editing capabilities are the most useful part of AutoCAD system, by making use of the alreadyexisting drawing. For the purpose of editing an object, it is necessary to make selection of theobjects in the drawing. There are various options available for the selection of an object:

1. Pick box—the cursor is converted to a small box/square, called pick box. By pressingthe left button of the mouse when the pick box touches an entity, the object can beselected for editing.

2. Window option—a single or group entities can be selected by bringing them fully insidea rectangular window. Entities, which lie only partially inside the boundaries of window,will not be selected. Rectangular window may be created by picking the first corner, bypressing the left button and then moving the mouse to the desired position of diagonallyopposite corner. Selection of the object is complete, by pressing the button again.

Figure 3.10 3.11. Edit Commands

The commands used for modifying the drawings fall under this category. Using these commands,the objects may be erased, retrieved, moved to another location, made into multiple copies,rotated, enlarged, mirror imaged, part of a drawing may be moved and the above effects canalso be reversed (undo).

ERASE Command—this lets the entities to be permanently removed from the drawing.The command format is

Command: ERASE

Select objects: (desired objects) once it is entered, the objects/portion of the object is erased/deleted.

OOPS Command—this restores the entities that have been inadvertently ERASED.Whenever ERASE command is used, a list of entities erased is retrieved by this command.

Command :OOPS

Once it is entered, it restores all the entities erased by the recent ERASE command.Once another ERASE is done, the list of entities erased by the previous ERASE command isdiscarded. OOPS cannot be used to restore them.

AutoCAD allows backup step by step to an earlier point in an editing session, usingthe UNDO command. This stores all the sequences made by the user in the current drawingsession.

UNDO Command—this command allows to undo several commands at once. Thiscommand is used for correcting any errors made in the editing process. When a SAVE option isused, then the UNDO cannot do anything before that.

Command: UNDO

If the response contains a number, that many number of preceding operations will beundone.

REDO Command—if REDO is entered immediately after a command that undoessomething, it will undo the UNDO.

Command: REDO

An UNDO after REDO will redo the original UNDO.

OFFSET Command—this constructs an entity parallel to another entity at either aspecified distance or through a specified point.

MIRROR Command—this allows to mirror the selected entities in the drawing. Theoriginal objects can be deleted (like a move)/retained (like a copy).

MOVE Command—the move command is used to move one/more existing drawing entitiesfrom one location in the drawing to another.

COPY Command—this is used to duplicate one or more existing drawing elements atanother location without erasing the original.

ZOOM Command

This command acts like a Zoom lens on a camera. It is used to change the scale of the display.This can be used to magnify part of the drawing to any higher scale, for looking closely at somefine detail in the drawing. This is often quite useful during the construction stage. If

All /Centre/Dynamic/Left /Previous/Vmax/Window/ <scale>:By choosing the option:

All — complete drawing is seen in the drawing limits, even though a part of thedrawing lies outside the limits, earlier.

Centre — this option permits to specify the desired centre point. By specifying theheight of window, the magnification can be increased/decreased.

Left — it permits to specify the lower left corner of the display window instead ofthe centre.

Dynamic — this displays the portion of the drawing specified already. Generally selectsany portion of the drawing.

Extents — all the objects in the drawing are magnified to the largest extent possiblein display.

Previous — the previous display extents are restored to the monitor, but the erasedobjects do not reappear.

Window — by entering two opposite corners of a window, the area inside the windowis enlarged /reduced.

Cross-hatching and Pattern Filling

It is common practice to fill an area with a pattern of some sort. The pattern can help differentiatebetween components, or it can signify the material composition of an object. This is accomplished by HATCH command. Hatching generates line entities for the chosen pattern and adds them tothe drawing. AutoCAD normally groups these lines into a general block.

HATCH Command—performs hatching. The pattern filling is illustrated in Fig. 3.11, by selecting appropriate choice in response to HATCH command.

Command: HATCH

Pattern (? Name/ u, style) <default>:

Pattern name may be entered by choosing various available patterns which will bedisplayed by choosing u, by interaction, the angle, spacing between the lines and double hatcharea may be specified. By choosing style (Fig. 3.11), pattern filling may be achieved.

Figure 3.11

Utility Commands

END Command — this command exits the drawing editor and returns to the mainmenu and updates the drawing file.

SAVE Command — this command saves the new/modified drawing and returns to themain menu. However, without exiting the drawing editor, if thechanges are to be periodically saved, it is desirable to use thiscommand. It protects the work from possible power failures, editingerrors, etc.

Command Save

File name <current>: return to save the current file

QUIT Command — this exits the drawing editor without saving the updated versionof the current drawing and returns to the main menu. The AutoCAD checks up with the user for one more confirmation to avoid theaccidental quitting since all the editing work done would be lost.

TEXT Command — text may be added to a drawing by means of the TEXT command.Text entities can be drawn with a variety of character patterns orfonts and can be stretched, compressed or drawn in a verticalcolumn by applying a style to the font.

Command: TEXT

Start point or Align/Centre/Fit/Middle/Right/Style:

By choosing:

Start point — Left justifies the text base line at the designated point.

A (Align) — prompts for two end points of the base line and adjusts overall charactersize so that text just fits between these points.

C (Centre) — asks for a point and centers the text base line at that point.

F (Fit) — similar to ‗align‘, but uses a specified fixed height.

M (Middle) — like ‗centre‘, but centers the text both horizontally and vertically at thedesignated middle point.

R (Right) — right justifies the text base line at that point.

S (Style) — asks for a new text style.

Null reply — places the new text directly below the highlighted text.