Lecture 2 -Create 2D Basic Drawing.pptx

7/30/2019 Lecture 2 -Create 2D Basic Drawing.pptx

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CREATE 2D BASIC

DRAWING

BDA 10102

COMPUTER AIDED DESIGN

Lecturers name:1. Ashari bin Kasmin

2. Abd Khalil bin Abd Rahim

3. Muhammad Aimullah bin Abdullah

4. Helmy bin Mustafa El Bakri5. Muhammad bin Zulkipli


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After completing this chapter, you will be able to:

Identify the default coordinate system and use dynamic input, directdistance, and shortcut menus.

Use the Line, Circle, Arc, Erase, Rectangle, and Polygon commands tocreate 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 moreaccurately 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 smallarchitectural floor plan.

Use the concepts and tools that.

Objectives


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Inputting Data

The following image illustrates

how to use the Dynamic Inputinterface to draw a 10mm line at30 degrees.

Every drawing action requires some form of data input.Regardless of the types of geometry you create, you areconstantly inputting data in one form or another.


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Command options appear on the command line. Thecapitalized letter(s) represents the letter(s) you enter to usethat option. You are not required to enter the letter(s) as acapital letter.

Options for the command appear within [...] brackets. Ifthere is a default option for the command, it appears within brackets. To use the default option, press ENTER.

Command Line Options


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The Dynamic Input interface is a way of entering datadynamically. Rather than entering data on the commandline, which is generally positioned at the bottom of thescreen, you can use the Dynamic Input interface for

heads-up design, entering command information onscreen at the cursor location.

Dynamic Input

1. Tooltip2. Coordinate, Length, or

Angle input fields3. Down Arrow.4. Dynamic Input Menu


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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


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The following image illustrates a line drawn from theorigin of the coordinate system 0,0 with its endpoint atthe coordinate 4,6.

Cartesian Coordinate Systems

To specify a Cartesian coordinate,type the X and Y coordinates andpress ENTER. Example: 4,6 whereX is equal to the distance from theorigin along the X axis and Y is

equal to the distance from theorigin along the Y axis.


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A polar coordinate is a point in the coordinate system that isdetermined by a distance and an angle.

The following illustration shows a line drawn from the origin ofthe coordinate system with a length of 7 units and an angle of

45 degrees.

Polar Coordinate Systems

To specify a polar coordinate, typethe distance < angle, example5


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Polar Angle

The default polar angle is measured counter clockwise fromthe zero angle position. The default zero angle is in the Eastcompass direction.


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The following lines could have been drawn usingCartesian or Polar coordinates. Assuming the start pointat the red arrow, the command line input for relativeCartesian or Polar coordinates would be as follows:

Point 2: @4,0 or @4


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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


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The following illustration shows a line segment beingdrawn using the dynamic input interface to specify thelength (1) and angle (2) of the segment.

Line Command

Line options can be selectedfrom the shortcut menu or typedat the Command line (L).


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In the following image, the circle centre point is selectedand you are prompted to specify a radius.

Circle Command

Circle options can be selected fromthe shortcut menu or typed at theCommand line (C).


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The following illustration represents an arc being createdthrough three points.

Arc Command

Arc options can be selected fromthe shortcut menu or typed at theCommand line (Arc).


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This illustration shows a rectangle with the point used tocreate it specified.

Rectangle Command


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Use the Polygon command to create regular polygongeometry by specifying the center point and radius of animaginary circle, or the start point and endpoint of one ofthe polygon edges.

Polygon Command


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Object Snap

Every object you create has various selectable points thatyou 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 followingare the object snap modes available in AutoCAD.

ENDpoint MIDpoint

INTersection APParent Intersection CENter

QUAdrant

TANgent

EXTension PERpendicular

PARallel INSert NODe

NEAest

From


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The ENDpoint Object Snap modesnaps to the closest endpoint of aline or an arc. To use this ObjectSnap mode, select the Endpointbutton, and move the cursor(crosshairs) anywhere close to theendpoint of the object. The marker

will be displayed at the endpoint;click to specify that point. For figure,invoke the LINE command from theDraw toolbar. The following is the

prompt sequence:

ENDpoint Object Snap mode

Specify first point: Select the Endpoint button from the ObjectSnap toolbar.

_endp of Move the crosshair and select the arc.

Specify next point or [Undo]: Select the endpoint of the line.

Endpoint


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The MIDpoint Object Snap mode snaps to the

midpoint of a line or an arc. To use this Object Snapmode, 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 modeSpecify first point: Select the starting point of theline.

Specify next point or [Undo]: Choose the Snap toMidpoint button from the Object Snap toolbar.

_mid of Move the cursor and select the original

line.

Midpoint


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The CENter Object Snap mode allows you to snap to the

center point of an ellipse, circle, or arc. For figure, invoke theLINE 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 theLINEcommand 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 Tangentbutton from the Object Snap toolbar.

_tan to Move the cursor and select the circle.

Specify next point or [Undo]: Select the endpoint of theline (tangent of the circle).

TANgent Object Snap mode

Center

Tangent


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The QUAdrant Object Snap mode is used when you need

to snap to a quadrant point of an ellipse, arc, or circle. Acircle 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


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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. Theprompt 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.


After selecting the Intersection

object snap, if your cursor is close toan 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 IntersectionObject Snap mode

Intersection


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The PERpendicular Object Snap mode is used to draw a

line perpendicular to or from another line, or normal to orfrom 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 drawperpendicular.


PERpendicular Object Snap

mode

Selecting the perpendicular

snap first

Perpendicular


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The NEArest Object Snap mode selects a point on

an object (line, arc, circle, or ellipse) that is visuallyclosest 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 promptsequence: 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


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Units represent the baseline of all the geometry that you create inyour drawing. It is up to you to determine what unit ofmeasurement will be used in your drawing.

About Units & Setting


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END

OF

LESSON 2

Lecture 2 -Create 2D Basic Drawing.pptx

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