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PublisherThe Goodheart-Willcox Co., Inc.Tinley Park, Illinois


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Chapter 6

CADD Commands

and Functions


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Chapter 6 Overview• Introduction• Drawing Commands• Editing and Inquiry Commands• Display Control Commands• Dimensioning Commands• Drawing Aids• Colors and Linetypes• Blocks and Attributes• 3D Drawing and Viewing Commands


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Learning Objectives

• List several general categories of commands used in popular CADD programs.

• Sketch an example of linear, angular, and leader dimensioning.

• Explain drawing aids.

• Discuss the purposes of colors, linetypes, and layers in typical CADD programs.

(continued)


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Learning Objectives

• Explain layer naming conventions as related to architectural drawings.

• Describe 3D drawing.

• Explain rendering.

• Explain animation.


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Introduction

• CADD is a powerful tool, but you have to know how to use it.– Commands are the instructions you

provide to the software to achieve the end result.

– Several general groups of commands are common to most CADD software.


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Introduction

• Command groups include:– Drawing commands.– Editing commands.– Display control commands.– Dimensioning commands.– Drawing aid commands.

• Names may vary between software, but the functions are the same.


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Introduction

• There may be more than one way to enter a command:– From a pull-down menu.– From toolbars that contain buttons.– Typing on the command line.– From a tablet menu.

• The method of entry is unimportant with respect to the function of the command.


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Drawing Commands

• Drawing commands form the foundation of any CADD program.– These commands allow you to create

objects on the screen.– The most basic drawing command is the

LINE command.– Many CADD programs automate the

creation of certain objects.


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Drawing Commands

• LINE command is the most frequently used command because it is the basic element in most drawings. Generally, you can enter coordinates or endpoints on the screen.


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Drawing Commands

• DOUBLE LINE command is useful in creating walls on floor plans or where parallel lines are required. Generally, you can set the distance between the double lines.


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Drawing Commands

• CIRCLE command automates the creation of a circle object. You can generally select from several common methods of defining a circle.


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Drawing Commands

• An arc is a portion of a circle. The ARC command automates the creation of an arc.


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Drawing Commands

• The RECTANGLE command automates the process of creating a square or rectangle. At least two methods are generally provided for constructing a rectangle.


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Drawing Commands

• The POLYGON command generates a regular polygon. This command can create an object with three or more sides.


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Drawing Commands

• The TEXT command adds text to a drawing. Most CADD packages provide several standard text fonts to choose from.


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Drawing Commands

• The HATCH command is used to hatch an area of a drawing. Hatching is used in section views and as exterior building materials and topographical features.


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Editing and Inquiry Commands• Editing commands allow you to modify

drawings in several ways.• Inquiry commands list database

records; calculate distances, areas, and perimeters; and convert points to absolute coordinates.

• Editing and inquiry commands include:– ERASE, UNDO, MOVE, COPY, MIRROR,

ROTATE, FILLET, CHAMFER, EXTEND, ARRAY, SCALE, LIST, DISTANCE, AREA.


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Editing Commands

• The ERASE command removes selected objects from the drawing.

• The UNDO command reverses the last command.

• The MOVE command allows objects to be moved, but does not change orientation or size.


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Editing Commands

• The COPY command is used to place copies of selected objects at specified locations.


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Editing Commands

• The MIRROR command creates a mirror image of an object.


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Editing Commands

• The ROTATE command is used to alter orientation of an object.


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Editing Commands

• The SCALE command changes the size of objects.– Some CADD programs are parametric.

• The FILLET command places fillets and rounds on the drawing.– A fillet is a smoothly fitted internal arc.– A round is an exterior arc.


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Editing Commands

• The FILLET command creates fillets and rounds.


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Editing Commands

• The CHAMFER command places a straight line between edges.

• The EXTEND command is used to lengthen an object to a boundary edge.

• The ARRAY command makes multiple copies of an object in a rectangular or circular pattern.


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Editing Commands

• This illustration was developed using the ARRAY command.


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Inquiry Commands

• The LIST and PROPERTIES commands show properties related to an object.

• The DISTANCE command measures the length and angle between two points.

• The AREA command calculates the area of an enclosed space.


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Inquiry Commands

• The AREA command was used to calculate the area of this enclosed space.


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Display Control Commands

• Display control commands are used to control how a drawing is shown on the screen.– They control the position and magnification

of the screen window.– They save views for later use.– These commands are used to redraw or

“clean up” the screen.


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• Display control commands include:– ZOOM– PAN– VIEW– REDRAW– REGENERATE


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• The ZOOM command increases or decreases the magnification factor, which changes the apparent size of objects on the screen.

• The PAN command moves the drawing in the display window from one location to another; it does not change the magnification factor.


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• This illustration demonstrates how the PAN command works.

(Eric K. Augspurger; print courtesy of SoftPlan Systems, Inc. )


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• The VIEW command speeds the process of switching between views.

• The REDRAW command “cleans up” the display by removing marker blips, etc.

• The REGENERATE command recalculates objects in the drawing and redraws the screen.


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Dimensioning Commands

• Drawings must show lengths, distances, and angles.

• One of the advantages of using CADD is automated dimensioning.

• Basic dimensioning commands include:– LINEAR –RADIUS– ANGULAR –LEADER– DIAMETER


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• LINEAR: Measures a straight line distance.

• ANGULAR: Measures the angle between two nonparallel lines.

• DIAMETER: Measures the distance across a circle through its center.

• RADIUS: Measures the distance from the center of an arc to a point on the arc.

• LEADER: Provides for a specific note.


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• Various dimensions appear on this drawing.


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Drawing Aids

• Drawing aids are designed to speed up the drawing process and maintain accuracy.– Grids range from display grids or viewport

ruler to various forms of snap.– Drawing aids commands include GRID,

SNAP, and ORTHO.


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Drawing Aids

• GRID. A display grid is a visual guideline in the viewport much like the lines on graph paper. Dots are also used to show the grid.


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Drawing Aids

• SNAP– Snap is a function that allows the cursor to

“grab” certain locations on the screen.– Two types: grid snap and object snap.

• ORTHO– Ensures that all lines drawn are orthogonal

(vertical or horizontal) in the drawing plane.


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Drawing Aids

• LAYER– A layer is a virtual piece of paper on which

objects are placed.– Objects on layers may or may not be

visible.– Managing layers is a function of CADD.– Layers may or may not be plotted.– Layer naming/usage standards are useful.– Consistency is very important.


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Colors and Linetypes

• Object display color is an important tool.– Color helps visually catalog objects in a

drawing.– Adopt a standard for color usage.

• The Alphabet of Lines– Always follow the Alphabet of Lines.– Linetypes are assigned to objects.– Linetypes may be assigned by layer.


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Blocks and Attributes

• Blocks are special objects (symbols) inserted into the drawing.– Blocks save time by reducing work.– A symbols library is a collection of blocks.

• An attribute is text information saved with a block when it is inserted into a drawing.– Attributes can be assigned when the block

is created.


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• This window block contains attributes, which have values assigned.


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• This is the AutoCAD command sequence for inserting the block shown in the previous slide and assigning attribute values.


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3D Drawing and Viewing Commands

• Early CADD programs were 2D only.

• 3D capabilities were added later.– Isometric and perspective drawings.– 3D modeling capabilities.

• 3D modeling capabilities allow you to design, model, and analyze an object within the computer.


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Isometric Drawing

• An isometric drawing is a traditional 2D pictorial drawing. It shows a 3D representation, but is really two dimensional.

(Eric K. Augspurger)


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3D Modeling• A type of 3D drawing is

called 3D modeling. This is “true” 3D where objects are created with a width, depth, and height.



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3D Modeling

• Two basic types: surface and solid.

• Surface modeling draws a skin over a wireframe.– The skin has no thickness.– A wireframe represents edges on the

models.

• Solid modeling creates objects by generating a volume.– Can be analyzed for mass, volume, etc.


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3D Views

• CADD software that is 3D-capable typically has a HIDE command to remove lines that are not visible.

• Most software provides for view rotation to see features better.


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Rendering Commands

• Rendering is the ability to shade or color the model .– Rendering has traditionally been done by

hand.– The MATERIAL command is used to apply

surface textures to 3D objects.– The RENDER command is used to “color”

the object.


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Rendered 3D Drawing

• This is a very realistic rendering with proper lighting and materials.

(Helmuth A. Geiser, Member AIBD)


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Animation Commands

• Animation adds movement to a drawing.– Specialized software is usually required.– Animation uses a series of still images to

simulate movement.– The ANIMATE command is used to add

movement.


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Animation Commands

• This window has been animated to show it opening and closing.


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