课程: AutoCAD 2025 Essential Training

Using OSNAP and AUTOSNAP for precise geometry - AutoCAD教程

课程: AutoCAD 2025 Essential Training

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Using OSNAP and AUTOSNAP for precise geometry

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- [Instructor] We're starting another chapter now and we're going to start taking a look at creating some basic simple geometry in an AutoCAD drawing. Now we've got a new drawing for you. It's GNDFloorPlan.DWG, so that's G-N-D floor plan dot D-W-G. You can download it from the library to follow along with the videos in this particular chapter. As you can see, it's the floor plan that we've used previously. We're going to zoom in on this area here. You can see there's two little circular tables. Zoom in a bit there and pan upward so that you're looking at this sector between the grid lines. I'm going to go in one more notch on the zoom so that you can see what I'm doing nice and clearly. Notice you are in this area here where there's furniture. You should, therefore, be using a furniture layer. Now there's one here, A 700 MFFE. That is the layer that you should be on when you open up the drawing and you're in the model tab down here on the left. Now just make sure that you are using that FFE layer, like that, it's that one there, a 700 MFFE. Just make sure that's the current drafting layer, and then you match all the rest of the furniture in the drawing. Now we're going to create a simple rectangle, using the rectangle command first. Now I know we haven't really touched on the rectangle command, but it's very quick and easy to do. So home tab on the ribbon, into the draw panel, and in the draw panel, top right of the panel, there's a little fly out there, select rectangle on that fly out. It'll prompt you for the first corner point of your rectangle. I'm going to pick a point about there and left click, drag upwards to the right, and you can see, it's basically forming a rectangle, using the opposing diagonal corner, like so. Now this particular table is going to be 3,500 millimeters by 2,500 millimeters. So I can type there three five zero zero. Again, that direct distance entry, press tab, you get the other vertical distance of the rectangle. That's going to be two five zero zero. Press tab again, that locks those in, like so, and then just left click. Your rectangle is drawn, at those particular sizes. Now that's our rectangle. So now we need to start thinking about utilizing object snaps, O snap, and what they call object snap tracking, which is now known as auto snap. Now these are down here on the status bar. So there's object snap tracking, auto snap. It's very simple, it's either on or off. Make sure it's blue for on. There's our object snaps there. Again, make sure they're on and blue. Click on the little arrow here, and you want to make sure that these five object snaps are ticked, endpoint, midpoint, center, intersection and extension. We will be utilizing those as we go through the O snap and the auto snap in this particular video. So make sure they're there. Just click away from the menu, it'll disappear. Now, what we're going to do is we're going to utilize a line and some object snaps to draw a circle in the center of our rectangular table first. Now just before we do that, you might want to make sure that this is on your polar tracking as well. I used it all the time. Just make sure that polar tracking is on. Click on the little fly out there, make sure it's at 90 degrees. It should be anyway because we haven't changed it since the last time we used it. But just click on 90 there and make sure it's on 90. We're going to draw a line now, you've done that previously. So draw panel, click on the line command, and we're going to use object snaps. So we're going to go object snap on this endpoint snap. See it there? When you hover over the corner, endpoint appears, left click. That's your object snap from that corner. We're now going to go down to this corner, and again, you'll get another endpoint snap. Left click, and there's your line. Just press enter to finish. You don't need to draw anything apart from that diagonal line, that's it. Now we're going to draw a circle now. So we go up to the draw panel again, click on the circle fly out, and select center radius. Come into the drawing area, hover over your diagonal line, there's your midpoint snap. Soon as you see it appear, left click. And then as you drag outwards, there's the radius of the circle. So what we'll do, we'll do a 900 radius circle. Type 900 in the box, press enter, and there's our circle of 900 radius. Now that diagonal line is sacrificial. So what you would do now is select it, right click, erase it. Now we've had to add extra geometry to draw that circle, but using the auto snap, the object snap tracking in AutoCAD, you can do that in a very different way. So click on the circle, select it, you'll see the grips appear, right click, and erase the circle on the shortcut menu. Let's do it a different way. Let's go to that circle command again. Click on the fly out and select center radius. Now you're thinking, "Hang on a minute, how do I pick a center point in the center of that rectangle, how do I get that?" Well, you need to make sure, down here, that your auto snap, your object snap tracking is on, and it is, and we know that that midpoint snap is working 'cause we've already used it. Now you've got to remember not to click when I tell you. Hover over the midpoint here. When the midpoint snap appears, do not click. As you move away, you'll see a little sort of cross appear. Can you see the little green cross? That's known as a blip. Go up here, hover over this midpoint, and then as you move away again, you'll see another little blip. Can you see those two little green crosses? As you move around and get to the center of the rectangle, those two little crosses draw two polar tracking lines that intersect. That is your auto snap, your object snap tracking. When you see them intersect like that, left click. You are now dead center of the rectangle. And as you come out, you can type in your 900 for your radius again, and you've got exactly the same circle. So what you've done there with the object snap tracking is hovered over two points to let AutoCAD know that you're object snap tracking off of those two points. And basically it shows you where the two lines that drawn through those points intersect. That's known as object snap tracking or auto snap. It's very quick and easy, isn't it? It's very useful. And you can have up to seven object snap tracking points. So select your circle again, right click and erase it again. There's one more clever, little method of object snaps that you can use to place that circle dead center of that rectangle. AutoCAD has a geometric center object snap. Now I haven't switched that on in our little snap list down here. If you click here, you can see there, there's geometric center, but I haven't ticked it, and I don't want you to tick it. So click away from the menu and that will disappear. I want to show you what is called snap overrides. So we're going to go back up to the draw panel, click on the circle fly out, and select center radius, and come into the drawing area. Now it says, "Center point for circle." Hold down the shift key on your keyboard and right click. That will bring up your snap overrides. Then you select geometric center on the menu that appears. As you hover over the rectangle, you'll see a funny little circle with a star in it. That is your geometric center of the rectangle. Left click. And as you can see, it's placed exactly in the geometric center of the rectangle. Again, type 900, press enter, and you've got exactly the same circle in the center of that rectangular table. Lots of different methods of drawing exactly the same thing, but you'll notice that things like your object snap tracking and your geometric center can be incredibly useful and save you having to draw extra geometry to create other bits of geometry in your drawings.

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