Specifying 3D coordinates
Specifying 3D coordinates
In this lesson you will learn about 3D coordinates. And how to separate coordinate entry using what are called point filters. Point filters allow you to draw objects relative to other object's coordinates. Open the Concept2 project file. And zoom into this red object. Draw a line, and snap its first point right here on this corner. Let's specify the next point using 3D Cartesian coordinates.
I'll start by entering the at symbol to indicate that I want to input relative coordinates. That is, they're relative to the last point that I selected. If you don't type at, you'll be inputting absolute coordinates. So those are going to be relative to the origin point of the coordinate system itself. So usually when you're entering coordinate data, you're going to preface it with the at symbol. I'll go ahead and input the x coordinate of 24, comma, to say that I'm moving on to the y coordinate.
Now let's say that will be zero. And then comma again to say that I'm moving on to the z coordinate, and I'll type 12, Enter, Enter. So we've drawn a line that is 24 units in the x direction. That's this red direction. And you can see that either on the cursor itself or on the UCS icon. The mnemonic is RGB equals XYZ.
Now, let's look at this in the top view. I'll zoom in. You can see here that the line goes horizontally here. It has no value in the y coordinate. And let's look at it in the front view. It goes up, in the z direction. So if you remember, the coordinate was 24 units over, zero units in the y direction, and 12 units up in the z direction.
So that specified that point. Now, there are many occasions where you simply want to draw a line relative to another object. And you don't really want to worry about the coordinates. For this you can use point filters. For example, let's say we want to draw a line from this same start point, and we want to draw it up vertically just as tall as the cone is high. So instead of querying information about the cone and learning the coordinates, and possibly writing them down, and then inputting them, which is very tedious. It's much more efficient to use a point filter to do this work for you. So let's think about it.
We want to filter out the coordinates. And we want to separate them. So we know the x y coordinates of the point that we want to specify. That's going to be directly above this point. So I'm going to type in point xy. This tells AutoCad that we're specifying a point filter, and we're going to use the x and y coordinates of the picked point. So, I'll type Enter. And then I'll pick this same point again.
Now the command line says Need Z. We've successfully separated the coordinates out, you see. Now, we still need to input the missing coordinate. And we'll do that simply by clicking on the top of this cone. Press Enter to end the line command. So I've successfully drawn a line straight up, just as tall as the cone is high. Let's try this again. Let's say this time, I want to draw a line from this corner point on this red object.
And I want to draw it in this direction. And I want it to stop right about here, lining up with the center of this cylinder. If I snap it directly to the center of the cylinder, well then we go from point to point, and that's not my intention. So, I'll go undo. Let's try this again. We'll draw the line from this point. And I want to specify the coordinates of this point in the x z plane.
And if you look at the cursor or the UCS icon, you can imagine how that plane looks. It's running on the front face of the red object, if you will. You can also see that over here on the view cube. So on the command line, I'm going to type point, x, z, Enter. And then I'm going to click right here on the center of this object. So I used the cursor to specify those two dimensions, and now AutoCAD is asking me for the missing dimension. It says need y.
So I'm going to specify that by clicking back on this original point. And then press Enter to end the line command. So point filters work by separating the entry into two different phases. In the first phase, you're asked to pick the point on the screen. And in the second phase, you're asked to either input that with a number, or you can pick another point, to specify the missing dimension. So, in this lesson, you learned how to use point filters to separate how you enter coordinates in different dimensions.
In this way, you can snap objects relative to specific dimensions of other objects.
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