AutoCAD Basics 2004 bible phần 7 pps

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750 Part IV ✦ Drawing in Three Dimensions Using DVIEW To create a perspective view, type dview ↵ on the command line. At the Select objects or <use DVIEWBLOCK>: prompt, select the objects you want to include in the process of defining the perspective view. You should select as few objects as you need to visualize the final result if you have a complex drawing. If you want to select the entire drawing, type all ↵ even if the current view doesn’t display the entire drawing. Press Enter if you don’t want to choose any objects. AutoCAD substitutes a block called dviewblock, which is a simple house. You can use the house to set your per- spective view. If you want, you can create your own block and name it dviewblock. Create it with X, Y, and Z dimensions of 1. When you press Enter at the Select objects or <use DVIEWBLOCK>: prompt, AutoCAD looks for dviewblock and uses it to dis- play the results of the perspective view settings. Understanding the DVIEW options DVIEW comes with a bewildering array of options that you use to specify the angle and distance of the view. To use these options, start the DVIEW command and select the objects you want to view or press Enter. You see the following prompt: Enter option [CAmera/TArget/Distance/POints/PAn/Zoom/TWist/CLip/Hide/Off/ Undo]: You use these options to define the perspective view, as explained in the following sections. CAmera Use the Camera option to specify the angle of the camera, which represents where you are standing. You need to specify the angle from the X axis in the XY plane and the angle from the XY plane. This is very similar to the way you specify a view using the DDVPOINT command, explained earlier in this chapter. When you choose this option, by right-clicking and choosing Camera, you see the following prompt: Specify camera location, or enter angle from XY plane, or [Toggle (angle in)] <35.2644>: Tip 539922 Ch22.qxd 5/2/03 4:13 PM Page 750 751 Chapter 22 ✦ Viewing 3D Drawings The default angle is based on the current view when you start DVIEW. If you know the angle from the XY plane, you can just type it in. You can also move the cursor vertically to dynamically see the results. The view constantly changes as you move the cursor, moving up over your objects as you move the cursor up, and down as you move the cursor down. Move the cursor in one direction and then keep it still for a second to see the full effect. However, moving the cursor horizontally changes the angle from the X axis in the XY plane. It can be confusing to change both angles at once so AutoCAD enables you to limit the effect of your cursor movement to one angle. You do this with the Toggle suboption. Right-click and choose Toggle (angle in) to see the next prompt of the Camera option: Specify camera location, or enter angle in XY plane from X axis, or [Toggle (angle from)] <66.12857>: Now, your cursor affects only the angle from the X axis. Move the cursor horizon- tally to see your objects rotate around you at a constant altitude. Press Enter when you like what you see, or you can type in an angle. If you want to set the angle in the XY plane first and limit the effect of cursor movement to that change, you need to use the Toggle suboption to get to the Enter angle in XY plane from X axis: prompt. After you set the angle in the XY plane, the suboption ends. Start the Camera option again to set the angle from the XY plane. TArget The Target option (right-click and choose Target) works exactly like the Camera option except that it defines the angles for the target of your viewpoint — what you would see through the camera lens. However, the angles are relative to the camera position. If you have already set the camera angles, the target angles default to those created by drawing a straight line from the camera angle through 0,0,0. As with the Camera option, use the Toggle suboption to switch between the two angles you need to specify. Distance The Distance option is very important because using it turns on perspective mode. Before you use this option, the views you see are parallel views. When you use the Distance option, you see a slider bar at the top of the screen, as shown in Figure 22-36. After you choose a distance, AutoCAD replaces the UCS icon with the perspective mode icon if your UCS display is set to 2D. (Choose View➪ Display➪ UCS Icon ➪ Properties.) Tip 539922 Ch22.qxd 5/2/03 4:13 PM Page 751 752 Part IV ✦ Drawing in Three Dimensions Figure 22-36: Using the Distance option turns on perspective mode and displays a slider bar. AutoCAD displays the Specify new camera-target distance <3.0000>: prompt. You can type a distance from the camera to the target or use the slider bar. Move the cursor to the right to zoom out. Moving the cursor to 4x is equivalent to using the ZOOM command and typing 4x ↵. Move the cursor to the left of 1x to zoom in. The zoom factor is relative to the current display so that 1x leaves the zoom unchanged. You can also type a distance in drawing units. POints You can use the Points option (right-click and choose Points) to define the camera and target. AutoCAD displays the Specify target point <0.3776, -0.1618, 1.0088>: prompt. The default target point, which is different for each drawing, is the center of the current view. AutoCAD places a rubber-band line from the target point, which you can use to get your bearings when choosing a new target point. You can also type a coordinate. At the Specify camera point <-1.5628, 0.9420, 2.2787>: prompt, pick or type a point. AutoCAD keeps the rubber-band line from the target so that you can visualize the camera and target points. Because it is difficult to know what 3D points you are picking, you should use an object snap or XYZ point filters to pick points. 539922 Ch22.qxd 5/2/03 4:13 PM Page 752 753 Chapter 22 ✦ Viewing 3D Drawings While it is common to choose a target point on one of the objects in your drawing, often you want the camera point to be off the objects so that you are looking at the objects from a certain distance and angle. To pick the camera point, choose Format ➪ Point Style (before starting DVIEW) and choose an easily visible point style. Decide what elevation you want, type elev ↵ and set a new elevation. From plan view, choose Point from the Draw toolbar and pick a point. The point is cre- ated on the current elevation. Then use the Node object snap to snap to the point when specifying the camera point in the Points option. Even though the Points option sets both distance and angle for the camera and tar- get points, you still need to use the Distance option to turn on perspective mode. PAn You cannot use the regular PAN or ZOOM commands within DVIEW, so DVIEW has its own Pan and Zoom options. At the Specify displacement base point: prompt, pick any point. At the Specify second point: prompt, pick the point to which you want the first point to pan. The model moves the distance and direction indicated by an imaginary line from the base point to the second point. Zoom The Zoom option displays the same slider bar you see with the Distance option, explained previously. If perspective mode is not on, you see the Specify zoom scale factor <1>: prompt, which works like the Distance option slider bar. If perspective mode is on, you see the Specify lens length <50.000mm>: prompt. A shorter lens length, such as 35mm, zooms you out, giving a wider angle view. A longer lens length, such as 70mm, zooms you in, giving a narrower angle view. Although the prompt shows a default in the form 50.000mm, you can only type in a number. Omit the mm. TWist The Twist option turns your objects around in a circle parallel to the current view you have defined. The default is zero (0) degrees, which is no twist. Assuming your current view looks at the objects right side up, 180 degrees turns the objects upside down, as if you had turned the camera in your hands upside down. AutoCAD dis- plays a rubber-band line from the center of the view, which you can use to pick a twist point, or you can type in an angle. CLip The Clip option enables you to create front and back planes that clip off the view. Objects in front of the front clipping plane or behind the back clipping plane are not displayed. You can use the front clipping plane to clip off a wall in front of the cam- era, letting you see through the wall to the objects beyond—a kind of AutoCAD X-ray vision. Use the back clipping plane when you want to exclude objects in the Note Tip 539922 Ch22.qxd 5/2/03 4:13 PM Page 753 754 Part IV ✦ Drawing in Three Dimensions distance from your perspective view. The clipping planes are always perpendicular to the line of sight, so you only need to set their distance from the target point. Compare Figure 22-37 to Figure 22-35. In Figure 22-37, the front posts and brackets have been clipped so that they no longer obscure the rest of the model. Figure 22-37: This model has a front clipping plane that hides the front of the model. Compare it to Figure 22-35. When you choose the Clip option, you see the Enter clipping option [Back/Front/Off] <Off>: prompt. Specify Back or Front to set the back or front clipping planes. Specify Off to turn off all previously defined clipping planes. When you use the Distance option to create a perspective view, AutoCAD auto- matically turns on a front clipping plane at the camera point. When you specify the Front suboption, AutoCAD responds with the Specify distance from target or [set to Eye(camera)/ON/OFF] <2.5682>: prompt. Specify Eye to set the clipping plane at the camera point. You can define the clipping plane by typing in a distance or using the slider bar that appears at the top of your screen. As you move the cursor on the slider bar, stop to let the drawing redraw so you can see the result. When you specify the Back suboption, AutoCAD displays the Specify distance from target or [ON/OFF] <-5.5826>: prompt. Specify On or Off to turn the clipping plane on or off, or specify the distance as for the front clipping plane. Hide The Hide option performs a hide, just like the HIDE command, letting you clearly see the results of the view you have created. Note 539922 Ch22.qxd 5/2/03 4:13 PM Page 754 755 Chapter 22 ✦ Viewing 3D Drawings Off The Off option turns off perspective mode and returns you to a parallel view. Otherwise, when you leave DVIEW after going into perspective mode, AutoCAD retains the perspective view until you change the view—for example, with VPOINT. Until then, you cannot pick points on the screen or use object snaps, which can be very frustrating. This option enables you to exit from DVIEW in the normal viewing mode. Undo The Undo option undoes the effect of the last DVIEW option. You can undo through all the changes you have made in DVIEW. The drawing used in the following Step-by-Step exercise on creating perspective views, ab22-e.dwg, is in the Drawings folder of the AutoCAD 2004 Bible CD-ROM. Step-by-Step: Creating Perspective Views 1. Open ab22-e.dwg from the CD-ROM. 2. Save it as ab22-03.dwg in your AutoCAD Bible folder. This is a portion of a 3D house in plan view, as shown in Figure 22-38. Make sure that OSNAP is on. Set a running object snap set for endpoint and turn off any other object snaps. 3. You want to create a perspective view from approximately 1 to 2 in Figure 22-38. You can see right away that the wall near 1 will need clipping. To get the distance of the clipping plane from the target, choose Tools ➪ Inquiry ➪ Distance and pick 3 and 4. The pertinent information is Distance = 12'-5 9/16" . You may get a slightly different distance. To see the distance informa- tion, press F2 to open the AutoCAD Text window. 4. Choose View ➪ 3D Views ➪ NE Isometric. The result is as shown in Figure 22-39. This is a quick approximation and helps you plan your camera and tar- get points. To test for endpoints, start the LINE command. Place the cursor at 1 in Figure 22-39. The Endpoint SnapTip and marker appear. Place the cursor at 2, the top of the table leg. You should see the Endpoint SnapTip and marker. Press Esc to cancel the LINE command without drawing a line. 5. Type dview ↵. At the Select objects or <use DVIEWBLOCK>: prompt, type all ↵. Press Enter to end object selection. 6. At the main DVIEW prompt, right-click and choose Points. At the Specify target point <14'-5 15/16", 21'-9 3/8", 6'-1 1/4">: prompt, pick the endpoint at 2 in Figure 22-39. At the Specify camera point <14'-6 15/16", 21'-10 3/8", 6'-2 1/4">: prompt, pick the endpoint at 1. On the CD-ROM 539922 Ch22.qxd 5/2/03 4:13 PM Page 755 756 Part IV ✦ Drawing in Three Dimensions Figure 22-38: A 3D house in plan view Thanks to Andrew Wilcox of Virtual Homes, Inc., Hammonds Plains, Nova Scotia, Canada, for this drawing. I have used only a small portion of it. Figure 22-39: The NE isometric view of the house 7. Right-click and choose Distance. At the Specify new camera-target dis- tance <20'-10 15/16">: prompt, move the cursor to 4x on the slider bar. Take your hand off the mouse to let the drawing redraw until you can see the result. Pick at the 4x mark. Notice the perspective view icon. 8. To move the camera point, right-click and choose Camera. At the Specify camera location, or enter angle from XY plane, or [Toggle (angle in)] <11.7252>: prompt, type 8 ↵ to lower the camera point 1 4 2 5 3 3 1 2 4 539922 Ch22.qxd 5/2/03 4:13 PM Page 756 757 Chapter 22 ✦ Viewing 3D Drawings slightly. At the Specify camera location, or enter angle in XY plane from X axis, or [Toggle (angle from)] <11.72523>: prompt, move the cursor close to 3 in Figure 22-39 relative to the screen, not the model and click. 9. Right-click and choose Zoom. At the Specify lens length <35.000mm>: prompt, type 60 to zoom in slightly. 10. Right-click and choose Clip. Right-click and choose Front to set the front clip- ping plane. At the Specify distance from target or [set to Eye(cam- era)] <83'-7 1/2">: prompt, type 13' ↵. AutoCAD hides the front walls that are blocking the view. 11. Right-click and choose Pan. At the Specify displacement base point: prompt, pick 4 in Figure 22-39 relative to the screen, not the drawing. At the Specify second point: prompt, pick 5 relative to the screen. The display moves down. 12. Right-click and choose Hide to hide the drawing. Your drawing should look approximately like Figure 22-40. 13. Press Enter to end the DVIEW command. 14. After all that work, you should save the view. Choose View➪ Named Views. On the Named Views tab, click New. In the New View dialog box, type Perspective 1 in the View Name text box. Click OK. Click OK to return to your drawing. 15. Save your drawing. Figure 22-40: The final perspective view 539922 Ch22.qxd 5/2/03 4:13 PM Page 757 758 Part IV ✦ Drawing in Three Dimensions Laying Out 3D Drawings Laying out a 3D drawing on a layout tab is an important aspect of viewing a 3D drawing, because the layout determines the final output of the drawing. AutoCAD offers three commands that help you lay out your 3D drawing in paper space lay- outs — SOLVIEW, SOLDRAW, and SOLPROF. You can find them on the Solids toolbar. (Chapter 17 explains layouts.) Flatten converts 3D polylines to 2D and flattens everything except blocks. Look in \Software\Chap22\Flatten. Using SOLVIEW to lay out paper space viewports SOLVIEW automates the process of creating floating viewports and orthogonal views — views at right angles from each other. To start SOLVIEW, choose Setup View from the Solids toolbar. SOLVIEW has five options: ✦ UCS enables you to choose the UCS to work from as well as set the scale, cen- ter, and clipping corners of a floating viewport. Use this option first. After you choose a UCS, type in a scale. You can change this later if you want. Then SOLVIEW prompts you for the center of the view. Pick a point and wait until the 3D model regenerates. SOLVIEW continues to prompt you for a view cen- ter, letting you pick points until you like what you see. Press Enter to continue the prompts. The clipping corners are the corners of the viewport. At the Enter view name: prompt, type a name. SOLVIEW creates the first viewport. Choose a view name that describes the view, such as Top, Side, or East Elevation. This helps you when you start creating orthogonal views. ✦ Ortho creates orthogonal views. At the Specify side of viewport to project: prompt, pick one of the edges of the first viewport. Again, choose a view center and clip the corners to create the viewport. Type a name for this new view. If you don’t see the model properly when you pick the view center, continue with the prompts, picking clipping corners where you want them. Then pick the viewport (in model space with tile off) and do a Zoom Extents. You can then pan and zoom as you want. This problem can happen when you have several separate 3D objects in your drawing. ✦ Auxiliary creates inclined views. At the Specify first point of inclined plane: prompt, pick a point in one of the viewports. At the Specify second point of inclined plane: prompt, pick another point in the same viewport. The two points are usually at an angle to create the inclined view. At the Specify side to view from: prompt, pick a point. You then pick a view center and clipping corners, and specify a view name. On the CD-ROM 539922 Ch22.qxd 5/2/03 4:13 PM Page 758 759 Chapter 22 ✦ Viewing 3D Drawings ✦ Section creates cross sections. At the Specify first point of cutting plane: prompt, pick a point in a viewport. At the Specify second point of cutting plane: prompt, pick a point on the opposite side of the model to create a cross section. You then pick a side to view from, and enter the view scale, a view center, clipping corners, and a view name. ✦ eXit exits the command. (This option is not visible in the command prompt.) You can exit the command after using an option and restart the command to use another option, or you can use all the options and then exit the command at the end. Figure 22-41 shows an example with a top view, an orthogonal view from one side, an auxiliary view, and a section. Figure 22-41: An example of using SOLVIEW Using SOLDRAW to create hidden lines and hatching SOLDRAW uses the views created by SOLVIEW and creates 2D profiles that include solid and hidden lines to represent the profiles and hatching for sectional views. You must use SOLVIEW before using SOLDRAW. To use SOLDRAW, choose Setup Drawing from the Solids toolbar. SOLDRAW puts you into a paper space layout and prompts you to select objects, which means floating viewports. You can select all of them if you want. SOLDRAW then proceeds to automatically create the profile views. Figure 22-42 shows an example of the hatching created for a sectional view. 539922 Ch22.qxd 5/2/03 4:13 PM Page 759 [...]... or [Color/Layer] 77 5 28 539922 Ch23.qxd 77 6 5/2/03 9:40 AM Page 77 6 Part IV ✦ Drawing in Three Dimensions Face 6, vertex 4: : 7 ↵ Face 6, vertex 5: : ↵ Face 7, vertex 1: Face 7, vertex 2: : 8 ↵ Face 7, vertex 3: : 9 ↵ Face 7, vertex 4: : 10 ↵ Face 7, vertex 5: : 11 ↵ Face 7, vertex 6: : 12 ↵ Face 7, vertex 7: : ↵... Drawings folder of the AutoCAD 2004 Bible CD-ROM 77 3 28 539922 Ch23.qxd 77 4 5/2/03 9:40 AM Page 77 4 Part IV ✦ Drawing in Three Dimensions Step-by-Step: Drawing Polyface Meshes 1 Open ab23-b.dwg from the CD-ROM 2 Save it as ab23-02.dwg in your AutoCAD Bible folder Two hexagons have been drawn, one 24 inches above the other, on the Const layer, as shown in Figure 23-10 4 3 5 2 6 1 0 9 ! 8 7 @ Figure 23-10:... specify AutoCAD prompts you for each vertex in order, starting with (0,0) Vertex (0,1) is the second vertex in the first column Vertex (1,0) is the first vertex in the second column, starting from the bottom It’s a little confusing because AutoCAD starts the counting from zero (0), not 1 For the 3D Mesh in Figure 23-13, the last vertex is (4,2) 77 7 28 539922 Ch23.qxd 77 8 5/2/03 9:40 AM Page 77 8 Part... 23-8: The completed kitchen cabinet, including a window in the door 77 1 28 539922 Ch23.qxd 77 2 5/2/03 9:40 AM Page 77 2 Part IV ✦ Drawing in Three Dimensions Drawing Surfaces with PFACE PFACE draws surfaces called polyface meshes, which are a type of polyline However, you cannot edit them with PEDIT The best way to edit them is with grips AutoCAD designed PFACE for the creation of surfaces using AutoLISP... positive portion of X-axis . Drawings folder of the AutoCAD 2004 Bible CD-ROM. Step-by-Step: Creating Perspective Views 1. Open ab22-e.dwg from the CD-ROM. 2. Save it as ab22-03.dwg in your AutoCAD Bible folder. This is. the Drawings folder of the AutoCAD 2004 Bible CD-ROM. Step-by-Step: Drawing 3D Faces 1. Open ab23-a.dwg from the CD-ROM. 2. Save it as ab23-01.dwg in your AutoCAD Bible folder. This is a blank. XY plane, or [Toggle (angle in)] <11 .72 52>: prompt, type 8 ↵ to lower the camera point 1 4 2 5 3 3 1 2 4 539922 Ch22.qxd 5/2/03 4:13 PM Page 75 6 75 7 Chapter 22 ✦ Viewing 3D Drawings slightly.
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