Hi, I'm James Dunsmore, and this is AutoCAD 101
Chapter Three
In this chapter, I'll show you how to use the basic drawing
functions to create lines, rectangles, and other objects
Specifically, I'll cover drawing lines and polygons using
the line and rectangle commands, as well as drawing and manipulating
Poly lines using the polyline, join, polyline, edit, and
stretch commands
Let's get started.
The model window is the drawing area for 2D drawing.
You can think of it as an infinitely large piece of paper.
This allows us to create drawings in full scale or using
real world dimensions.
For example, if we're depicting a building that's 100ft long
by 60ft wide, the object in our drawing will have those dimensions
only when we want to reduce the size of our model to fit
on a piece of paper, will we select the scale, such as one
inch to 100ft, so that same 100 by 60 foot building can be
represented on an eight and a half by eleven inch piece of
paper. The model window is organized as a grid, with each
point having an X and Y coordinate representing its distance
from the origin.
You can change the basing of the grid using the grid command.
Now, let's get started drawing as a vector based drawing
program like SketchUp or Illustrator.
Lines are the basic element of AutoCAD drawings.
Every line has the same pieces, a start point, and an endpoint,
which is determined by its length.
To draw a line, either select the line function from the
toolbar or type line or the shortcut command L into the command
prompt. Now, don't be surprised when you don't see any lines
appear because we haven't given the program enough information
yet to generate a line.
We said what type of object we want to create.
We haven't said where we need to specify the first point
of the line as you can see from the command prompt.
To do this, simply click on the point you want within the
model window and you can see the coordinates of the current
point or type in the coordinates of a point you want to use.
For example, zero to start drawing from the origin.
Next, we need to specify the endpoint of the line, and this
works the same way.
Either click on the point you want to use, specify the coordinates
of the point you want, or you can type in the length of the
line you want to create.
For example, 65ft, the line command automatically repeats,
so you can continue to draw a series of lines.
Notice how each time it's showing me not only the length
of the line I'm about to create, as well as its angle away
from the X axis.
You'll also notice how the line command will snap to the
endpoint of the first line we created.
You can control object snapping using the Object Snap or
OSNAP command.
To do this type in OSNAP into the command prompt.
This brings up the Drafting Settings menu, and here you can
see which object snapping functions are on.
You can see it's currently set to snap to the endpoint midpoint,
center perpendicular as well as some other points, and you'll
notice there's a symbol associated with each object snap
mode. For instance, the square for endpoint, a triangle for
midpoint, a circle for center, or the right angle symbol
for perpendicular.
Whenever you're about to snap to a point on your drawing,
it'll show you the symbol of the point you're snapping to.
Let's see how that works.
So if we create a line and we want to draw from the center,
we'll see the triangle, which shows the midpoint of the line.
If we want to draw perpendicular to this line, we can see
here we're snapping to the midpoint, and here we're snapping
to a point perpendicular to the line we're connecting to
to erase the lines you've drawn, select the objects and type
erase, or simply hit delete.
Notice how as I create this series of lines, I'm able to
click on any point in the model window.
Well, this allows me to draw a variety of shapes.
It can make it difficult to draw shapes with right angles
or to align your drawing to the X and y axes.
If you want to draw straight lines parallel to the X and
y axes, you can use the Ortho command for orthogonal drawing.
To do this, simply type Ortho and turn orthogonal drawing
on. Now, you'll notice that as I draw lines, I'm only able
to draw lines that are parallel to the X and Y axis.
Well, it looks like we've just drawn a complete shape.
What we've actually drawn is multiple individual objects.
As you can see, each one can be manipulated or deleted separately.
In contrast, we can use the rectangle function from either
the toolbar or command prompt using the command rectangle
to create a single enclosed object as if the line function
specifies the first corner point of the rectangle and second
corner point, or specify the dimensions of the rectangle
you want to create.
But unlike with the line command, the resulting shape is
a single object.
You'll notice the difference between the two objects as I
attempt to select each one.
Selecting one side of the rectangle I just drew will select
the entire object because it's a single complete shape.
In contrast, selecting one side of the shape I drew using
the line command will select only that line segment.
That's because the shape on the left is comprised of individual
lines, whereas the shape on the right is comprised of a single
Poly line or aligned with multiple segments.
There are multiple ways to create Poly lines.
One way is to use the shape commands to create rectangles
and other polygons.
Another option is to use the polyline command either from
the toolbar or by typing Poly line or the shortcut command
PL into the command prompt.
You create Poly lines just as you would lines start by specifying
the first point and then a second point or a distance.
The only difference between Poly lines and lines are as you
can continue to draw line segments they're joined together.
Snapping works the same way you can see.
We can also snap to the endpoint, but we also have a few
other options when we create Poly lines.
For example, if we create this Poly line, pay attention to
the command prompt and see the other options.
Typing close will complete the object using the start point
as the endpoint.
There are a few other options, including Arc and I'll explain
these a little later.
Another way to create Poly lines is to convert lines into
Poly lines, and there are a few ways to do this, but the
simplest is to use the join commands to see how that works.
Let's start by selecting one of the lines we drew earlier
type in Properties to bring up the Properties menu.
Here, we can see what type of object we have.
We can see that this is a line and we can see the length
of the line.
Now let's minimize that and use the join command to join
these lines together.
Select each line you want to join and hit enter.
Now, if we select the object, we can see all the lines are
connected, and when we bring up the Properties window, we
can see there a Poly line.
If we look at the length, we see it's now the perimeter of
the rectangle, and we also see there's an area calculation
available, and this is another.
One of the benefits of Poly lines is that they enclose spaces
and allow you to measure area.
From a visual perspective.
There's no difference between an object comprised of lines
and an object comprised of Poly lines.
They look the same when printed, and they look the same on
the screen.
To see this, I'm going to undo the join command that I just
used, and you can do this using either the undo button or
typing you into the command prompt, and now we can see this
shape is a series of lines again, rather than Poly line,
and we can see its appearance hasn't changed.
And while Poly lines and lines look the same, there are a
few key benefits to using Poly lines.
As demonstrated, Poly lines allow you to calculate values
such as perimeter and area, and Poly lines also facilitate
manipulation. For example, we can grab one corner of this
polyline object and stretch it and the space remains enclosed.
Not so if we grab one edge of the object comprised of lines
in the same way, you can manipulate the edge of any segment
to change the size and shape of an object when it's comprised
of Poly lines.
For example, grabbing it in the middle, we can pull it down
to change the shape, whereas doing the same thing moves a
line. Rather than changing the shape of the object.
Now, both of these are applications of the stretch function.
As you can see if you look in the command history, and that
shows a third way to input commands, which is simply to perform
the action.
Poly lines can do a few other useful tricks as well.
For example, selecting a Poly line object and hovering over
one point or Vertex brings up additional options.
You can stretch or move that point, add additional points,
or remove the point.
To do this, select the option you want from the drop down
menu, or just type in the first letter of the option you
want, for example, R to remove, and you can see that option
clears that point and changes the shape of the object.
Another way to edit or change Poly lines is to use the Polyline
edit or P edit command to do this type in P edit and select
the Poly line you want to change.
Now we have additional options, including Open, which removes
the leg of the Poly line and Join, which allows us to connect
multiple Poly lines together.
You can also use the Polyline Edit command to convert lines
into Poly lines.
To do this type Petit like the line you want to convert to
a Poly line, you'll see it says select polyline, and if you
select the non polyline object, it will say, do you want
to turn it into one hit?
Yes.
And now you can see we have options to manipulate that Poly
line, including connecting it to others.
If you bring up the property menu, you can see what was aligned
is now a Poly line.
This is a useful command, especially later when we're dealing
with arcs and circles.
For now, let's use the Poly line command to get started drawing.
If we're going to create a site plan, we need a project site
and we're going to create this using a polyline.
To begin, select polyline from either the toolbar or typing
polyline or PL into the command prompt and give yourself
a starting point.
I'll use zero again.
Our site needs a length.
I'll use one 200ft as well as a width.
Let's say 800ft.
Go ahead and create a complete object and snap either to
the end point or use the close command and to complete the
shape. Now we've created the property outline for our site
plan. In the next chapter, I'll show you how to organize
your drawing using layers as we add buildings and rows to
our project site.