This document discusses how to create basic 2D drawings in AutoCAD, including: - Using coordinate systems, object snaps, and dynamic input to accurately place lines, circles, arcs, rectangles, and polygons. - The main drawing tools covered are the Line, Circle, Arc, Rectangle, Polygon commands as well as the Erase command. - Object snaps like Endpoint, Midpoint, Center, Tangent, and Perpendicular allow placing objects precisely relative to other existing geometry.

1. CHAPTER 2 :
CREATE 2D BASIC
DRAWING

2. After completing this chapter, you will be able to:
•Identify the default coordinate system and use dynamic input, direct
distance, and shortcut menus.
•Use the Line, Circle, Arc, Erase, Rectangle, and Polygon commands to
create and erase geometry in the drawing.
•Use object snaps to accurately place and create objects in the drawing.
•Activate and use the Polar Tracking and PolarSnap modes to more
accurately create geometry at different angles in the drawing.
•Explain, enable, and use object snap tracking to position geometry in the
drawing.
•Use the Unit command to set up the drawing environment.
•Use the concepts and tools that you learned in Chapter 2 to begin a small
architectural floor plan.
•Use the concepts and tools that.
Objectives

3. Inputting Data
The following image illustrates
how to use the Dynamic Input
interface to draw a 10mm line at
30 degrees.
Every drawing action requires some form of data input.
Regardless of the types of geometry you create, you are
constantly inputting data in one form or another.

4. •Command options appear on the command line. The
capitalized letter(s) represents the letter(s) you enter to use
that option. You are not required to enter the letter(s) as a
capital letter.
•Options for the command appear within [...] brackets. If
there is a default option for the command, it appears within
<...> brackets.To use the default option, press ENTER.
Command Line Options

5. The Dynamic Input interface is a way of entering data
dynamically. Rather than entering data on the command
line, which is generally positioned at the bottom of the
screen, you can use the Dynamic Input interface for
heads-up design, entering command information on
screen at the cursor location.
Dynamic Input
1. Tooltip
2. Coordinate, Length, or
Angle input fields
3. DownArrow.
4. Dynamic Input Menu

6. Every object you draw is placed in either the world coordinate
system (WCS) or a user coordinate system (UCS). When you
create 2D geometry, data input is ultimately passed to the
software in the form of Cartesian (x,y) or polar coordinates
(distance, angle). You can either manually enter these
coordinates or infer them by picking a point in the drawing
window.
Coordinate System

7. The following image illustrates a line drawn from the
origin of the coordinate system 0,0 with its endpoint at
the coordinate 4,6.
Cartesian Coordinate Systems
To specify a Cartesian coordinate,
type the X and Y coordinates and
press ENTER. Example: 4,6 where
X is equal to the distance from the
origin along the X axis and Y is
equal to the distance from the
origin along theY axis.

8. A polar coordinate is a point in the coordinate system that is
determined by a distance and an angle.
The following illustration shows a line drawn from the origin of
the coordinate system with a length of 7 units and an angle of
45 degrees.
Polar Coordinate Systems
To specify a polar coordinate, type
the distance < angle, example
5<45, where Distance equals the
distance travelled from the
specified origin point and Angle
equals the angle from the X axis.

9. Polar Angle
The default polar angle is measured counter clockwise from
the zero angle position. The default zero angle is in the East
compass direction.

10. The following lines could have been drawn using
Cartesian or Polar coordinates. Assuming the start point
at the red arrow, the command line input for relative
Cartesian or Polar coordinates would be as follows:
Point 2: @4,0 or @4<0
Point 3: @0,2 or @2<90
Point 4: @-1,0 or @1<180
Example of Cartesian or Polar
Coordinate Input

11. All drawings consist of basic objects that you create using
basic commands. In this lesson, you learn how to create
objects such as lines, circles, arcs, rectangles, and
polygons. You also learn how to use the Erase command
to erase objects.
Creating Basic Objects

12. The following illustration shows a line segment being
drawn using the dynamic input interface to specify the
length (1) and angle (2) of the segment.
Line Command
Line options can be selected
from the shortcut menu or typed
at the Command line (L).

13. In the following image, the circle centre point is selected
and you are prompted to specify a radius.
Circle Command
Circle options can be selected from
the shortcut menu or typed at the
Command line (C).

14. The following illustration represents an arc being created
through three points.
Arc Command
Arc options can be selected from
the shortcut menu or typed at the
Command line (Arc).

15. This illustration shows a rectangle with the point used to
create it specified.
Rectangle Command

16. Use the Polygon command to create regular polygon
geometry by specifying the center point and radius of an
imaginary circle, or the start point and endpoint of one of
the polygon edges.
Polygon Command

17. Object Snap
Every object you create has various selectable points that
you can use to position other objects. Every time you
create an object you are required to specify a point or
location. It is critical that these points be defined accurately
if you expect your drawing to be accurate. The following
are the object snap modes available in AutoCAD.
• ENDpoint
• MIDpoint
• INTersection
• APParent Intersection
• CENter
• QUAdrant
• TANgent
• EXTension
• PERpendicular
• PARallel
• INSert
• NODe
• NEAest
• From

18. The ENDpoint Object Snap mode
snaps to the closest endpoint of a
line or an arc. To use this Object
Snap mode, select the Endpoint
button, and move the cursor
(crosshairs) anywhere close to the
endpoint of the object. The marker
will be displayed at the endpoint;
click to specify that point. For figure,
invoke the LINE command from the
Draw toolbar. The following is the
prompt sequence:
ENDpoint Object Snap mode
Specify first point: Select the Endpoint button from the Object
Snap toolbar.
_endp of Move the crosshair and select the arc.
Specify next point or [Undo]: Select the endpoint of the line.
• Endpoint

19. The MIDpoint Object Snap mode snaps to the
midpoint of a line or an arc. To use this Object Snap
mode, select Midpoint osnap and select the object
anywhere. AutoCAD will grab the midpoint of the
object. For figure, invoke the LINE command from the
Draw toolbar.The following is the prompt sequence.
MIDpoint Object Snap mode
Specify first point: Select the starting point of the
line.
Specify next point or [Undo]: Choose the Snap to
Midpoint button from the Object Snap toolbar.
_mid of Move the cursor and select the original
line.
• Midpoint

20. The CENter Object Snap mode allows you to snap to the
center point of an ellipse, circle, or arc. For figure, invoke the
LINE command from the Draw toolbar. The following is the
prompt sequence:
Specify first point: Choose the Snap to Center button from the
Object Snap toolbar.
_cen of Move the cursor and select the circle.
Specify next point or [Undo]: Select the endpoint of the line.
CENter Object Snap mode
For figure, invoke the LINE command from the Draw toolbar.
The following is the prompt sequence:
Specify first point: Select the starting point of the line.
Specify next point or [Undo]: Choose the Snap to Tangent
button from the Object Snap toolbar.
_tan to Move the cursor and select the circle.
Specify next point or [Undo]: Select the endpoint of the
line (tangent of the circle).
TANgent Object Snap mode
• Center
• Tangent

21. The QUAdrant Object Snap mode is used when you need
to snap to a quadrant point of an ellipse, arc, or circle. A
circle has four quadrants, and each quadrant subtends an
angle of 90-degree. If the circle is inserted as a block, that
is rotated, the quadrant points are also rotated by the
same amount, see figures.
To use this object snap, position the cursor on the circle or
arc closest to the desired quadrant, see figure.
Quadrants in a rotated
circle
Location of circle quadrants
QUAdrant object snap mode
• Quadrant

22. The INTersection Object Snap mode is used to snap to a point where two or more
lines, circles, ellipses, or arcs intersect. For figure, invoke the LINE command. The
prompt sequence is given next.
INTersection Object
Snap mode
Specify first point: Choose the Snap to Intersection button from the Object Snap toolbar.
_ int of Position the cursor near the intersection and select it.
Specify next point or [Undo]: Select the endpoint of the line.
After selecting the Intersection
object snap, if your cursor is close to
an object and not close to an actual
intersection, the intersection marker
displays ellipses [...] with it. This
indicates an extended intersection.
This mode selects extended or
visual intersections of lines, arcs,
circles, or ellipses (figure). Extended Intersection
Object Snap mode
• Intersection

23. The PERpendicular Object Snap mode is used to draw a
line perpendicular to or from another line, or normal to or
from an arc or circle, or to an ellipse. The prompt
sequence to draw a line perpendicular to a given line
(figure) is given next.
Specify first point: Select the starting point of the line.
Specify next point or [Undo]: Choose the Snap to Perpendicular
button from the Object Snap toolbar.
_per to Select the line on which you want to draw perpendicular.
The prompt sequence for drawing a line perpendicular
from a given line (figure) is given next.
Specify first point: Choose the Snap to Perpendicular button
from the Object Snap toolbar.
_per to Select the line on which you want to draw
perpendicular.
Specify next point or [Undo]: Select the endpoint of the line.
PERpendicular Object Snap
mode
Selecting the perpendicular
snap first
• Perpendicular

24. The NEArest Object Snap mode selects a point on
an object (line, arc, circle, or ellipse) that is visually
closest to the graphics cursor (crosshairs). To use
this mode, enter the command, and then choose
the Nearest object snap. Move the crosshairs near
the intended point on the object so as to display
the marker at the desired point and then select the
object. For figure, invoke the LINE command from
the Draw toolbar. The following is the prompt
sequence: NEArest Object Snap mode
Specify first point: Choose the Snap to Nearest button
from the Object Snap toolbar.
_nea to Select a point near an existing object.
Specify next point or [Undo]: Select endpoint of the line.
• Nearest

25. Units represent the baseline of all the geometry that you create in
your drawing. It is up to you to determine what unit of
measurement will be used in your drawing.
About Units & Setting

26. END
OF
LESSON 2