MasteringAutoCAD 2011 and AutoCAD LT 2011 phần 8 pps

Visualizing solids | 833 You can access more detailed settings for the 2D Section/Elevation, 3D Section, and Live Section Settings options by clicking the Section Settings button at the bottom of the Generate Section/ Elevation dialog box. This button opens the Section Settings dialog box (Figure 24.50), which lists the settings for the section feature. Figure 24.48 The Generate Sec- tion/Elevation dialog box Click the button to expand the dialog box. Figure 24.49 A copy of the solid minus the section area is created using the 3D Section option of the Generate Section/Elevation dialog box. 621974c24.indd 833 4/26/10 12:40:00 PM 834 | CHAPTER 24 Editing and Visualizing 3d solids If you create a set of orthogonal views in a layout, the work you do to find a section is also reflected in the layout views (Figure 24.51). Figure 24.50 The Section Settings dialog box Figure 24.51 A set of orthogonal views in a layout 621974c24.indd 834 4/26/10 12:40:00 PM Visualizing solids | 835 Taking Advantage of Stereolithography A discussion of solid modeling wouldn’t be complete without mentioning stereolithography. This is one of the more interesting technological wonders that has appeared as a by-product of 3D computer modeling. Stereolithography is a process that generates physical reproductions of 3D computer solid models. Special equipment converts your AutoCAD-generated files into a physical model. This process offers the mechanical designer a method for rapidly prototyping designs directly from AutoCAD drawings, though applications don’t have to be limited to mechanical design. Architects can take advantage of this process too. My own interest in Tibetan art led me to create a 3D AutoCAD model of a type of statue called a Zola, shown here. I sent this model to a service to have it repro- duced in resin. AutoCAD supports stereolithography through the 3dprint and Stlout commands. These com- mands generate an STL file, which can be used with a Stereolithograph Apparatus (SLA) to generate a model. You must first create a 3D solid model in AutoCAD. Then you can use the Export Data dialog box to export your drawing in the STL format. Choose Export  Other Formats from the Application menu, and make sure the Files Of Type drop-down list shows Lithography (*.stl) before you click the Save button. You can also choose Send To 3D Print Service from the Output tab’s 3D Print panel. The AutoCAD 3D solids are translated into a set of triangular-faceted meshes in the STL file. You can use the Rendered Object Smoothness setting in the Display tab of the Options dialog box to control the fineness of these meshes. See Chapter 23 for more information on this setting. When you use the Send To 3D Print Service tool in the 3D Print panel, you will see a message box asking if you want to learn more about preparing a 3D model for printing. If you are unfamiliar with stereolithography and 3D printing, it is a good idea to select the Learn About Preparing A 3D Model For Printing option so you don’t make some of the more common mistakes. 621974c24.indd 835 4/26/10 12:40:00 PM 836 | CHAPTER 24 Editing and Visualizing 3d solids The Bottom Line Understand solid modeling. Solid modeling lets you build 3D models by creating and join- ing 3D shapes called solids. There are several built-in solid shapes called primitives, and you can create others using the Extrude tool. Master It Name some of the built-in solid primitives available in AutoCAD. Create solid forms. You can use Boolean operations to sculpt 3D solids into the shape you want. Two solids can be joined to form a more complex one, or you can remove one solid from another. Master It Name the three Boolean operations you can use on solids. Create complex solids. Besides the primitives, you can create your own shapes based on 2D polylines. Master It Name three tools that let you convert closed polylines and circles into 3D solids. Edit solids. Once you’ve created a solid, you can make changes to it using the solid-editing tools offered on the Solid Editing panel. Master It Name at least four of the tools found on the Solid Editing panel. Streamline the 2D drawing process. You can create 3D orthogonal views of your 3D model to create standard 2D mechanical drawings. Master It What is the name of the tool in the Solid Editing panel that lets you create a 2D drawing of a 3D model? Visualize solids. In addition to viewing your 3D model in a number of different orientations, you can view it as if it were transparent or cut in half. Master It What is the name of the command that lets you create a cut view of your 3D model? 621974c24.indd 836 4/26/10 12:40:01 PM Chapter 25 Exploring 3D Mesh and Surface Modeling AutoCAD has always offered tools that allowed users to construct fairly complex 3D models. With the introduction of the latest solid modeling tools, you can even model some very organic forms. But there are some types of forms that require a type of modeling known as mesh modeling. Mesh modeling enables you to create smooth, curved volumes by manipulating faces that make up an object’s surface. With mesh modeling, you can quickly create curved shapes that are difficult or even impos- sible to create by other means. AutoCAD also offers the ability to convert a mesh model into a 3D solid so that you can perform Boolean operations. AutoCAD 2011 introduces a set of 3D surface modeling tools that extend its ability to pro- duce and edit curved, organic forms. In this chapter, you’ll get a chance to explore many of the current features of mesh modeling through a series of exercises, and you’ll be introduced to the new surface modeling tools. You’ll also learn how you can convert a mesh or 3D surface into a solid. You’ll start by creating a simple shape as an introduction, and then you’ll move on to a more complex form. In this chapter you’ll learn to do the following: Create a simple 3D mesh •u Edit faces and edges•u Create mesh surfaces•u Convert meshes to solids•u Understand 3D surfaces•u Edit 3D surfaces•u Creating a Simple 3D Mesh As an introduction to the mesh modeling features in AutoCAD, you’ll draw a simple box and then smooth the box. This first exercise will show you some of the basic mesh modeling tools and what types of control you can exert on a model. 621974c25.indd 837 4/26/10 12:40:06 PM 838 | CHAPTER 25 Exploring 3D MEsh anD surfacE MoDEling First make sure you are in the 3D Modeling workspace and that you have a blank drawing set up for the mesh. Then follow these steps: 1. Click the Workspace drop-down list in the Quick Access toolbar and select 3D Modeling. 2. Next, open a new file using the acad3D.dwt template. Click the New tool from the Quick Access toolbar. 3. At the Select Template dialog box, select the acad3D.dwt template and then click Open. 4. Choose the Shaded With Edges visual style from the Visual Styles drop-down list in the Home tab’s View panel. This will give you a close approximation of the appearance of meshes you’ll see in the figures shown in this book. Creating a Mesh Primitive Meshes are similar to solids in that they start from what is called a primitive. You may recall that 3D solid primitives are predetermined shapes from which you can form more complex shapes. The mesh primitives are very similar to the 3D solid primitives you learned about in Chapters 21 and 24. You can see the different mesh primitives that are available by clicking the Mesh fly- out in the Primitives panel (Figure 25.1). In the next exercise, you’ll use the Mesh Box primitive to start your cushion. 1. In the Mesh tab’s Primitives panel, click the Mesh Box tool, or type Mesh↵ B↵. Figure 25.1 The primitives in the Mesh flyout of the Primitives panel 621974c25.indd 838 4/26/10 12:40:06 PM crEating a siMplE 3D MEsh | 839 2. At the Specify first corner or [Center]: prompt, enter 0,0↵ to start the mesh at the drawing origin. 3. You’ll want a mesh that is 21 units in the X axis by 32 units in the Y axis, so at the Specify other corner or [Cube/Length]: prompt, enter 21,32↵. 4. At the Specify height or [2Point]: prompt, place your cursor anywhere above the base of the mesh and enter 4↵ for a 4-inch height. You now have a basic shape for your mesh (Figure 25.2). You’ve just created a mesh box, but you have several other mesh primitives at your disposal. If you click the Mesh flyout on the Modeling panel, you’ll see the cylinder, cone, sphere, pyra- mid, wedge, and torus primitives. When creating your model, consider which of these primi- tives will best suit your needs. Understanding the Parts of a Mesh Before you go any further, you’ll want to understand the structure of a mesh. Notice that each side is divided into nine panels, or faces, as they are called in AutoCAD. You can edit these faces to change the shape and contour of your mesh. You can control the number of faces of a mesh through an options dialog box that you’ll learn about later. Figure 25.3 shows the names of the different parts of a simple mesh: the vertex, the edge, and the face. These three parts are called subobjects of the mesh, and you can move their posi- tion in the mesh to modify a mesh’s shape. To help you select different subobjects on a mesh, the Subobject panel offers the Filter flyout, which shows the No Filter tool by default. You’ll get to use this flyout in many of the exercises in this chapter. Smoothing a Mesh One of the main features of a mesh is its ability to become a smooth, curved object. Right now your cushion has sharp edges, but you can round the corners using the Smooth tools. Try modifying the mesh to smooth its corners: 1. Click the rectangular mesh to select it. 2. Click the Smooth More tool in the Mesh panel or type Meshsmoothmore↵. The edges of the mesh become faceted and smoother in appearance. Figure 25.2 The Mesh Box primitive 621974c25.indd 839 4/26/10 12:40:06 PM 840 | CHAPTER 25 Exploring 3D MEsh anD surfacE MoDEling 3. Click Smooth More again. The mesh becomes smoother still (Figure 25.4). 4. Now click Smooth Less (just below the Smooth More tool) or type Meshsmoothless↵. The mesh becomes less smooth. 5. Press Esc to clear the selection. As you can see from this exercise, you can smooth a mesh using the Smooth More tool. The more times you apply it to a mesh, the smoother your mesh becomes. The number of faces of the mesh determines how the Smooth More tool affects the mesh. The fewer the faces, the broader the application of smoothness. When you apply the Smooth More tool to a mesh, the faces of the mesh become faceted. This simulates the smooth appearance. If you look closely at a mesh that has only one or two levels of smoothing applied, you can see the facets. Editing Faces and Edges The shape you created earlier demonstrates one of the main features of meshes. In this section, you’ll create a model of a surfboard to see how you can push and pull the subobjects of a mesh to create a form. Figure 25.3 The subobjects of a mesh Vertex Edge Face Figure 25.4 The mesh after applying the Smooth More tool twice 621974c25.indd 840 4/26/10 12:40:07 PM EDiting facEs anD EDgEs | 841 Know the ViewCube Throughout the following exercise, you’ll make heavy use of the ViewCube. Make sure you are familiar with how it works. If you need a refresher, go to Chapter 21. You’ll start with the same form, a box shape, but this time you’ll modify some of the param- eters that define the box’s structure. You can control the number of faces that a mesh primitive will have before it is created. The following exercise introduces you to the tools and methods used to edit meshes. Start by creating a new drawing and setting up the parameters for the mesh. 1. Click the New tool in the Quick Access toolbar, select acad3D.dwt, and then click Open. 2. In the Mesh tab, click the Mesh Primitive Option tool in the Primitives panel title bar. The Mesh Primitive Options dialog box appears (Figure 25.5). 3. In the Tessellation Divisions group, change the Length and Width values to 4 and the Height value to 1. Click OK when you’ve finished making the changes. 4. In the Home tab’s View panel, choose the Shaded visual style from the Visual Styles drop-down list. The parameters you change alter the number of faces on mesh primitives that you create, including the box primitive in the next exercise. You’ll see the results in the next set of steps: 1. Click the Mesh Box tool in the Primitives panel. 2. At the Specify first corner or [Center]: prompt, type 0,0↵ to start the corner at the origin of the drawing. 3. At the Specify other corner or [Cube/Length]: prompt, enter 50,30↵ to create a 50˝ × 30˝ base for the box. Figure 25.5 The Mesh Primitive Options dialog box 621974c25.indd 841 4/26/10 12:40:07 PM 842 | CHAPTER 25 Exploring 3D MEsh anD surfacE MoDEling 4. At the Specify height or [2Point] prompt, point the cursor in the positive Z direction and then enter 3.5↵ for a 3.5˝ thickness. 5. Center the box in your view. Your model should look similar to Figure 25.6. 6. Click the box to select it. Then, in the Mesh panel, click the Smooth More tool twice. The edges of the mesh become more rounded. What Does the Smooth Object Tool Do? It’s hard not to notice the very large Smooth Object tool in the Mesh panel. My first reaction was to try to use this tool on a mesh, but it is not intended to work on meshes. Instead, it converts 3D objects other than meshes into mesh objects. You can convert a solid into a mesh, for example, using this tool. 3D surfaces can also be converted, and it even works on region objects that are technically not 3D objects. You might be tempted to convert a mesh to a solid, edit it, and then turn it back into a mesh. Although this can be done, I wouldn’t recommend it. You’ll find that your model becomes too unwieldy to work with. Stretching Faces You now have the basis for the surfboard, though it might seem like an odd shape for a surf- board. Next you’ll start to form the surfboard by manipulating the faces and edges of the mesh. Start by pulling two sides of the mesh to give it a shape more like a surfboard: 1. Use the ViewCube and Pan tools to adjust your view so it looks similar to Figure 25.8. This view will allow you to easily select and “pull” some of the faces that will become the front and back of the surfboard. 2. In the Subobject panel, select Face from the Filter flyout (see Figure 25.7). 3. Click on the box mesh to expose its mesh lines. This will help you see where to place the selection window in the next step. 4. Hold down the Ctrl key and then click and drag a crossing selection window over the middle faces at the front edge of the box, as shown in Figure 25.8. The faces are high- lighted, and you see the XYZ gizmo. Figure 25.6 The mesh box 621974c25.indd 842 4/26/10 12:40:08 PM [...]... features the Spline Freehand tool, which will let you draw a curve “freehand” with a click and drag of your mouse Experienced AutoCAD users will recognize this Spline Freehand tool as an updated version of the Sketch command 621974c25.indd 86 1 4/26/10 12:40:20 PM 86 2  | Chapter 25  Exploring 3D Mesh and Surface Modeling Figure 25.35 A circle extruded using the solid Extrude and the surface Extrude 3D... select and “pull” some of the faces that will become the back of the surfboard 621974c25.indd 84 3 2 Click on the box mesh to expose its mesh lines again 4/26/10 12:40: 08 PM | Chapter 25  84 4  Exploring 3D Mesh and Surface Modeling 3 Hold down the Ctrl key and then place a crossing selection window over the middle faces at the back edge of the box as shown in Figure 25.10 The faces are highlighted, and. .. features of the Mesh toolset 621974c25.indd 85 0 4/26/10 12:40:14 PM | Editing Faces and Edges   85 1 Hover over this circle Figure 25.20 Click and drag the green circle on the Rotate gizmo Green axis extension Figure 25.21 Select the Rotate Gizmo tool Figure 25.22 The finished surfboard 621974c25.indd 85 1 4/26/10 12:40:15 PM | Chapter 25  85 2  Exploring 3D Mesh and Surface Modeling Changing the Gizmo on... extrusion 621974c25.indd 85 5 4/26/10 12:40:17 PM 85 6  | Chapter 25  Exploring 3D Mesh and Surface Modeling Figure 25. 28 A moved face and an extruded face Using Split Mesh Face and Add Crease Together In a “usability study” conducted by Autodesk, the product designers gave an example of how to add a crease to the top surface of a computer mouse model In the example, the Add Crease tool and the Split Face... Faces and Edges   84 3 Figure 25.7 Select the Face filter 5 Place your cursor on the red X axis of the gizmo 6 When the red axis extension line appears, click and drag the gizmo downward in a positive X direction The mesh begins to elongate 7 When your mesh looks similar to Figure 25.9, release your mouse 8 Press Esc to remove the faces from the current selection Figure 25 .8 Hold down the Ctrl key and. .. Adjust the edges so they look similar to those in Figure 25. 18, and then release the mouse 6 Adjust the X axis of the gizmo toward the back of the surfboard so the fins look similar to how they look in Figure 25.19 621974c25.indd 84 8 7 Press the Esc key to clear your selection of mesh edges 4/26/10 12:40:12 PM | Editing Faces and Edges   84 9 Figure 25.16 Ctrl+click these two faces Select the faces... you’re an old hand at using AutoCAD 3D, then these tools should be familiar They are the latest incarnation of some of the earliest 3D tools offered by AutoCAD, and they work exactly like the old features they replace But just like the mesh volumes you’ve been working with, the mesh surfaces can be quickly smoothed and their subobjects can be edited using the gizmos you learned about in this and earlier... solid later on See Chapter 24 for more on the solid editing tools Understanding 3D Surfaces So far in this book, you’ve worked with 3D solids and meshes A third type of 3D object called a surface completes AutoCAD s set of 3D modeling tools to make AutoCAD 2011 a complete 3D modeling application in its own right Click the Surface tab and you’ll see the Surface panels that offer the tools you’ll need to... some fins as separate meshes and then later join them to the surfboard You can also use the Refine Mesh tool to add more edges and then use those edges as the basis for your fins The following exercise will show how this is done: 621974c25.indd 84 7 1 Adjust your view so it looks similar to the top image in Figure 25.16 4/26/10 12:40:12 PM | Chapter 25  84 8  Exploring 3D Mesh and Surface Modeling 2 From... created are surfaces 621974c25.indd 86 5 4/26/10 12:40:24 PM | Chapter 25  86 6  Exploring 3D Mesh and Surface Modeling Using the Trim Tool Next try out the Trim tool: 1 Click Surface Trim from the Surface tab’s Edit panel 2 Click both the cylinder and the extruded arc surface, and then press ↵ This first step selects the objects to trim 3 Click both objects again and then press ↵ This time you’re selecting . the basic mesh modeling tools and what types of control you can exert on a model. 621974c25.indd 83 7 4/26/10 12:40:06 PM 83 8 | CHAPTER 25 Exploring 3D MEsh anD surfacE MoDEling First make. box 621974c25.indd 84 2 4/26/10 12:40: 08 PM EDiting facEs anD EDgEs | 84 3 5. Place your cursor on the red X axis of the gizmo. 6. When the red axis extension line appears, click and drag the gizmo. key and place a crossing selec- tion window as shown here. Crossing selection windowCrossing selection window 621974c25.indd 84 3 4/26/10 12:40: 08 PM 84 4 | CHAPTER 25 Exploring 3D MEsh anD