MasteringAutoCAD 2011 and AutoCAD LT 2011 phần 7 ppt

creAting coMplex 3d sUrFAces | 709 6. Change the color of the solid representing the seat to cyan, and then select the Realistic visual style from the Visual Styles flyout on the Home tab’s View panel. Your drawing will look similar to the image on the left of Figure 22.39, which shows a perspective view. The image on the right is the chair with some materials assigned to its parts and a slight adjustment to the seat location. 7. Close the file. You can save it or, if you intend to repeat the exercise, close and do not save. Using Sweep to Create Complex Forms Although you used circles with the Sweep command to create tubes, you can use any closed polyline shape. Figure 22.40 gives some examples of other shapes you can use with the Sweep command. Figure 22.39 A perspective view of the butterfly chair with tubes for legs Figure 22.40 You can use any closed shape with the Sweep command. 621974c22.indd 709 4/26/10 12:38:40 PM 710 | CHAPTER 22 Using AdvAnced 3d FeAtUres In step 3 of the previous exercise, you may have noticed some command-line options. These options offer additional control over the way Sweep works. Here is a rundown on how they work: Alignment This option lets you determine whether the object to sweep is automatically set perpendicular to the sweep path. By default, this option is set to Yes, which means the object to sweep is set perpendicular to the path. If set to No, Sweep assumes the current angle of the object, as shown in Figure 22.41. Base Point By default, Sweep uses the center of the object to sweep as the location to align with the path, as shown in Figure 22.42. Base Point lets you set a specific location on the object. Figure 22.41 Alignment lets you set the angle between the object to sweep and the sweep path. You can skew the object to sweep in relation to the sweep path by using the Alignment option. By default, the object to sweep is aligned perpendicular to the sweep path. Rotate the object to sweep to an angle away from the WCS, and then turn off the Alignment option. Figure 22.42 Using the Base Point option Sweep path By default, the center of the object to sweep is aligned with the sweep path. Base point Sweep path With the Base Point option, you can select a location on the object to sweep that will align with the sweep path. Center 621974c22.indd 710 4/26/10 12:38:41 PM creAting spirAl ForMs | 711 Scale You can have Sweep scale the sweep object from one end of the path to the other to create a tapered shape, as shown in Figure 22.43. This option requires a numeric scale value. Twist You can have the object to sweep twist along the path to form a spiral shape, as shown in Figure 22.44. This option requires a numeric value in the form of degrees of rotation. These options are available as soon as you select the sweep object and before you select the path object. You can use any combination of options you need. For example, you can apply the Twist and Scale options together, as shown in Figure 22.45. Creating Spiral Forms You can use the Sweep tool in conjunction with the Helix tool to create a spiral form, such as a spring or the threads of a screw. You’ve already seen how the Sweep tool works. Try the following to learn how the Helix tool works firsthand. Figure 22.43 Scale lets you scale the object to sweep as it’s swept along the path. Figure 22.44 You can have the object to sweep twist along the path to create a spiral effect. 621974c22.indd 711 4/26/10 12:38:42 PM 712 | CHAPTER 22 Using AdvAnced 3d FeAtUres In this exercise, you’ll draw a helicoil thread insert. This is a device used to repair stripped threads; it’s basically a coiled steel strip that forms internal and external threads. Here are the steps: 1. Open the Helicoil.dwg file. This is a standard AutoCAD drawing containing a closed polyline in a stretched octagon shape. This is the cross section of the helicoil thread, and you’ll use it as an object to sweep after you’ve created a helix. 2. Click the Helix tool in the Home tab’s expanded Draw panel, or type Helix↵. You see the following prompt: Number of turns = 3.0000 Twist=CCW Specify center point of base: Figure 22.45 The Scale and Twist options applied together 621974c22.indd 712 4/26/10 12:38:42 PM creAting spirAl ForMs | 713 3. Pick a point roughly in the center of the view. A rubber-banding line appears along with a circle. 4. At the Specify base radius or [Diameter] <1.0000>: prompt, enter 0.375↵. 5. At the Specify top radius or [Diameter] <0.3750>: prompt, press ↵ to accept the default, which is the same as the value you entered in step 4. 6. At the Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <1.0000>: prompt, enter T↵ to use the Turns option. 7. At the Enter number of turns <3.0000>: prompt, enter 15↵ to create a helix with 15 turns total. 8. At the Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <1.0000>: prompt, press ↵ to accept the default height of 1. The helix appears as a spi- ral drawn to the dimensions you’ve just specified for diameter, turns, and height (see Figure 22.46). In step 6, you used the Turns option to specify the total number of turns in the helix. You also have other options that give you control over the shape of the helix. Figure 22.47 shows you the effects of the Helix command options. You may want to experiment with them on your own to get familiar with Helix. Edit a Helix with the Properties Palette If you find that you’ve created a helix with the wrong settings, you don’t have to erase and re-create it. You can use the Properties palette to make adjustments to any of the helix options presented in Figure 22.47, even after a helix has been created. Select the helix, right-click, and choose Properties. Look in the Geometry section of the Properties palette for the helix settings. Figure 22.46 The helix and the helicoil after using Sweep 621974c22.indd 713 4/26/10 12:38:42 PM 714 | CHAPTER 22 Using AdvAnced 3d FeAtUres Now, use the Sweep tool to complete the helicoil: 1. Click the Sweep tool from the Extrude flyout in the Home tab’s Modeling panel, or enter Sweep at the Command prompt. 2. At the Select objects to sweep or [MOde]: prompt, select the thread cross section in the lower-left corner of the drawing, and then press ↵. 3. At the Select sweep path or [Alignment/Base point/Scale/Twist]: prompt, select the helix. After a moment, the helicoil appears. 4. To see the helicoil more clearly, choose the Realistic option from the Visual Styles drop- down list, and then change the helicoil to the helicoil layer. 5. Close and save the file. If you intend to repeat this exercise, close but don’t save. If the space between the coils is too small for the cross section, you may get an error message. If you get an error message at step 3, make sure you created the helix exactly as specified in the previous exercise. You may also try increasing the helix height. In step 3, instead of selecting the sweep path, you can select an option to apply to the object to sweep. For example, by default, Sweep aligns the object to sweep at an angle that is perpen- dicular to the path and centers the object to sweep. See “Using Sweep to Create Complex Forms” earlier in this chapter. Creating Surface Models In an earlier exercise, you used the Loft command to create the seat of a butterfly chair. In this section, you’ll return to the Loft command to explore some of its other uses. This time, you’ll use it to create a 3D model of a hillside based on a set of site-contour lines. You’ll also see how you can use a surface created from the Loft command to slice a solid into two pieces, imprinting the solid with the surface shape. Figure 22.47 The Helix com- mand options The tWist option lets you determine whether the helix twists clockwise or counterclockwise. Axis endpoint lets you select the endpoint of the helix to adjust the helix direction. The Turns option determines the number of turns in the helix. Center of base The turn Height option lets you specify the height between coils. 621974c22.indd 714 4/26/10 12:38:43 PM creAting sUrFAce Models | 715 Architectural Applications for the Helix Tool The helix example given here is a device often used to repair spark plug threads that have been stripped, but the helix can be used in other applications besides mechanical modeling. I’ve used a helix to draw a circular ramp for a parking garage. Instead of multiple turns, I would use a single rotation or a half rotation. The radius of the helix was much larger, to accommodate the width of a car. Old versus New Surfaces If you’ve used earlier versions of AutoCAD to create 3D models, you’ve probably used surface model- ing to create some of your 3D objects. If you open an old drawing file that contains those 3D surfaces, you’ll see that they are called polygon meshes. You can convert those older mesh objects into new surface objects using the Convert To Surface tool, which is next to the Convert To Solid tool in the Home tab’s expanded Solid Editing panel. If you prefer to use the older 3D surface modeling tools like Revsurf and Rulesurf, they are still available, though they now create mesh surfaces. You will learn more about mesh modeling in Chapter 25. Start by creating a 3D surface using the Loft command: 1. Open the contour.dwg file. 2. Click the Loft tool from the Extrude flyout on the Home tab’s Modeling panel. 3. Select each brown contour in consecutive order from right to left or left to right. It doesn’t matter whether you start at the left end or the right end, but you must select the contours in order. 4. When you’re finished selecting all the contours, press ↵ and wait a moment. AutoCAD requires a bit of time to calculate the surface. Once it does, you see the surface applied over the contour lines (Figure 22.48). 5. At the Enter an option [Guides/Path/Cross sections only/Settings] <Cross sections only>: prompt, press ↵ to exit the Loft command. Figure 22.48 Creating a 3D surface from contour lines 621974c22.indd 715 4/26/10 12:38:44 PM 716 | CHAPTER 22 Using AdvAnced 3d FeAtUres Once the loft surface has been placed, you can make adjustments to the way the loft is generated by using the arrow grip that appears when you select the surface: 1. Click the surface to select it. 2. Click the arrowhead that appears by the surface. This is known as a multifunction grip. Multifunction Grip 3. Select the Ruled option from the menu. The surface changes slightly to conform to the new Ruled surface option (Figure 22.49). In the butterfly chair exercise, you used the Guides option in the Loft Command prompt. This allowed you to use the polyline curves to guide the loft shape from the front arc to the back arc. In this exercise, you didn’t use the command options and went straight to the multifunction grip menu. The Ruled setting that you used in step 3 generates a surface that connects the cross sections in a straight line. You’ll learn more about the options in this grip menu later in this chapter. Slicing a Solid with a Surface In the barcelona1.dwg chair example, you converted a surface into a solid using the Thicken command. Next, you’ll use a surface to create a solid in a slightly different way. This time, you’ll use the surface to slice a solid into two pieces. This will give you a form that is more easily read and understood as a terrain model: 1. Click the Extrude tool from the Extrude flyout in the Home tab’s Modeling panel. Figure 22.49 The surface with the Ruled option selected 621974c22.indd 716 4/26/10 12:38:45 PM creAting sUrFAce Models | 717 2. At the Select objects to extrude or [MOde]: prompt, select the large rectangle below the contours, and press ↵. The rectangle turns into a box whose height follows your cursor. 3. At the Specify height of extrusion or [Direction/Path/Taper angle/Expression]: prompt, move the cursor upward so the box looks similar to the one in Figure 22.50. Then click the mouse to fix the box’s height. You may have noticed that as you raised the box height, you could see how it intersected the contour surface. Next you’ll slice the box into two pieces: 1. Click the Slice tool in the Home tab’s Solid Editing panel (Figure 22.51). 2. At the Select objects to slice: prompt, select the box and press ↵. 3. At the Specify start point of slicing plane or [planar Object/Surface/Zaxis/ View/XY/YZ/ZX/3points] <3points>: prompt, enter S↵ to use the Surface option. 4. At the Select a surface: prompt, select the contour surface. 5. At the Select solid to keep or [keep Both sides] <Both>: prompt, click the part of the box that is below the surface. The top part of the box disappears, and you see the surface once again. 6. Delete the contour surface and the contour lines. The box remains with an imprint of the surface, as shown in Figure 22.52. Figure 22.50 The box extruded through the contours Figure 22.51 The Slice tool 621974c22.indd 717 4/26/10 12:38:45 PM 718 | CHAPTER 22 Using AdvAnced 3d FeAtUres In step 3, you saw a prompt that offered a variety of methods for slicing the box. The Surface option allowed you to slice the box using an irregular shape, but most of the other options let you slice a solid by defining a plane or a series of planar objects. Finding the Volume of a Cut A question I hear frequently from civil engineers is “How can I find the volume of earth from an excavated area?” This is often referred to as a cut from a cut and fill operation. To do this, you first have to create the cut shape. Next, you use the Interfere command to find the intersection between the cut shape and the contour surface. You can then find the volume of the cut shape using one of AutoCAD’s inquiry commands. The following exercise demonstrates how this is done. Suppose that the contour model you’ve just created represents a site where you’ll excavate a rectangular area for a structure. You want to find the amount of earth involved in the excava- tion. A rectangle has been placed in the contour drawing representing such an area: 1. Select 3dWireframe from the Visual Styles flyout on the Home tab’s View panel (Figure 22.53). This allows you to see the excavation rectangle more clearly. 2. Turn on the Selection Cycling tool in the status bar. This will help you select the rectangle in step 3. 3. Click the Extrude tool in the Home tab’s Modeling panel. 4. Select the rectangle shown in Figure 22.54. 5. At the Selection dialog box, select Polyline and then press ↵. 6. Extrude the rectangle to the height of 10´. Figure 22.52 The box with the contour surface imprinted Figure 22.53 Select 3dWireframe from the Visual Styles flyout. 621974c22.indd 718 4/26/10 12:38:45 PM [...]... you select the cross sections affects the result of the Loft command Second Third Third Second First First 621 974 c22.indd 72 0 4/26/10 12:38: 47 PM | Creating Surface Models   72 1 Figure 22.58 Loft Settings: Smooth Fit You can radically affect the way the Loft command forms a surface or a solid through the options in this dialog box, so it pays to understand what those settings do Take a moment to study... also prompted for the distance between rows, columns, and levels 621 974 c22.indd 72 7 4/26/10 12:38:51 PM 72 8  | Chapter 22  Using Advanced 3D Features For the Polar option of 3D Array, you are prompted for the number of items to array, the direction, the angle to fill, and whether to rotate the arrayed objects, just as with the standard Array command In addition to being asked for a point to indicate... gizmo do?  ​ 621 974 c22.indd 72 8 4/26/10 12:38:52 PM Chapter 23 Rendering 3D Drawings In this chapter, you’ll learn how to use rendering tools in AutoCAD to produce rendered still images of your 3D models With these tools, you can add materials, control lighting, and even add landscaping and people to your models You also have control over the reflectance and transparency of objects, and you can add... Render tab’s Sun & Location panel (see Figure 23 .7) You may see a message box warning you that the default lighting must be turned off when other lights are used Click Turn Off The Default Lighting 621 974 c23.indd 73 4 2 Click the Set Location tool in the Render tab’s Sun & Location panel (Figure 23.8) 4/26/10 12:39:00 PM | Simulating the Sun   73 5 Figure 23 .7 Sun Status tool The tools available on the... Objects in 3D Space   72 5 2nd destination point Figure 22.64 Aligning two 3D objects 1st destination point 3rd destination point Result Figure 22.65 The 3D Move tool 2 Select the object or set of objects you want to move, and press ↵ The Move gizmo appears on the object (Figure 22.66) Figure 22.66 The Move gizmo The Move gizmo 621 974 c22.indd 72 5 4/26/10 12:38:50 PM | Chapter 22  72 6  Using Advanced... this, then the selected object begins to rotate You don’t have to select a start and end angle Using 3Dmirror and 3Darray Two other tools, 3D Mirror and 3D Array, are available in the Home tab’s Modify panel These are 3D versions of the Mirror and Array tools They work in a way that’s similar to how the standard Mirror and Array tools work, with a slight difference 3D Mirror begins by asking you to... created by the Loft command In the contour-map example, you selected the Ruled setting from a multifunction grip after you had completed the Loft command You can also set Loft command options through the Loft Settings dialog box (Figure 22.58) This dialog box appears during the Loft command when you select the Settings option after you’ve selected a set of cross sections Figure 22. 57 The order in which... prompt, you can and then press ↵ The AutoCAD Text Window appears, and it displays the properties of the excavation area At the top, you see the volume of the selected solid in cubic inches (Figure 22.56) press ↵ to exit the command or enter Y↵ to save the information to a text file Understanding the Loft Command As you’ve seen from the exercises in this chapter, the Loft command lets you create just about... transparency of objects, and you can add bitmap backgrounds to help set the mood AutoCAD LT 2011 doesn’t support any of the features described in this chapter In this chapter, you’ll learn to do the following: •u Simulate the sun •u Use materials •u Create effects using materials and lights •u Apply and adjust texture maps •u Understand the rendering options •u Add cameras for better view control •u Print... Browser and see how it can be used to create a more lifelike rendering Start by opening a sample file and render it as is 1 First turn on the Selection Cycling tool in the status bar You’ll need it in some of the later exercises 2 Make sure 3D Modeling is selected in the Workspace drop-down list in the upper-left corner of the AutoCAD window 621 974 c23.indd 72 9 4/26/10 12:38:58 PM | Chapter 23  73 0  . tool Figure 22. 57 The order in which you select the cross sections affects the result of the Loft command. First Third Second First Second Third 621 974 c22.indd 72 0 4/26/10 12:38: 47 PM creAting. The Scale and Twist options applied together 621 974 c22.indd 71 2 4/26/10 12:38:42 PM creAting spirAl ForMs | 71 3 3. Pick a point roughly in the center of the view. A rubber-banding line. Specify base radius or [Diameter] < 1.0000>: prompt, enter 0. 375 ↵. 5. At the Specify top radius or [Diameter] < 0. 375 0>: prompt, press ↵ to accept the default, which is the same as the