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664 Part IV Drawing in Three Dimensions

Figure 23-6: The completed kitchen cabinet, including a window in the door.

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 routines or other automated methods. Consequently, the input for polyface meshes is somewhat awkward. However, polyface meshes have the following advantages:

You can draw surfaces with any number of sides, unlike 3D faces, which can only have three or four sides.

The entire surface is one object.

Sections that are on one plane do not show edges so that you don’t have to bother with making edges invisible.

You can explode polyface meshes into 3D faces.

If you create a polyface mesh on more than one plane, each plane can be on a different layer or have a different color. This can be useful for assigning materials for rendering or other complex selection processes.

On the other hand, polyface meshes are difficult to create and edit. Figure 23-7 shows two polyface meshes — one on one plane and the other on three planes.

The prompts for PFACE are divided into two phases. The first phase simply asks for vertices. The second phase asks you to specify which vertex makes up which face (or plane). The second phase is fairly meaningless for polyface meshes on one plane, but you have to specify the vertices anyway. Here’s how to do it:

Chapter 23 Creating 3D Surfaces 665

1. Type pface .

2. At the Specify location for vertex 1: prompt, specify the first vertex.

3. Continue to specify vertices at the Specify location for vertex 2 or <define faces>: or Specify location for vertex 3 or <define faces>: prompts (and so on). Press Enter when you’ve finished.

4.At the Face 1, vertex 1: Enter a vertex number or [Color/Layer]: prompt,

type which vertex starts the first face of the polyface mesh. It’s usually vertex 1, so you type 1 .

5.At the Face 1, vertex 2: Enter a vertex number or [Color/Layer] <next face>: prompt, type which vertex comes next on the first face. Continue to specify the vertices for the first face.

If you’re drawing a polyface mesh on one plane, continue to specify all the vertices in order and press Enter twice when you’re done to end the command.

If you’re drawing a polyface mesh on more than one plane, continue to specify the vertices on the first face (that is, plane) and press Enter. At the Face 2, vertex 1: Enter a vertex number or [Color/Layer]: prompt, type the first vertex of the second face (plane) and continue to specify vertices for the second face. Press Enter. Continue to specify vertices for all the faces. Press Enter twice to end the command.

Tip

In order to easily draw a polyface mesh with PFACE, draw 2D objects as a guide for picking

 

vertices. Then you can use object snaps to pick the vertices. Also, for polyface meshes on

 

more than one plane, draw a diagram that numbers the vertices. This helps you specify

 

which vertices make up which face.

Eight-sided polyface

Polyface mesh

mesh on one plane

on three planes

Figure 23-7: You can create many-sided polyface meshes on one plane, or on several different planes. After you use the HIDE command, the polyface mesh hides objects behind it.

666 Part IV Drawing in Three Dimensions

During the second phase of the prompts, when PFACE asks you to define the faces, you can right-click and choose Layer or Color and specify the layer or color. Then specify the vertices that are to be on that layer or color.

In the following Step-by-Step exercise, you draw a hexagonal night table with polyface meshes.

On the

The drawing used in the following Step-by-Step exercise on drawing polyface meshes,

CD-ROM

ab23-b.dwg, is in the Drawings folder on the CD-ROM.

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 23-8.

4

3

5

2

6

1

0

9

!

8

@

7

Figure 23-8: The two hexagons are the basis for a night table.

3.Type pface . Follow the prompts. First you specify all the vertices. Then you specify the top hexagon, then the five sides (the front is open), and finally the bottom hexagon. Unfortunately, if you make a mistake, you must start over.

Specify location for vertex 1: Pick 1 in Figure 23-8.

Specify location for vertex 2 or <define faces>: Pick 2 in Figure 23-8.

Specify location for vertex 3 or <define faces>: Pick 3. Specify location for vertex 4 or <define faces>: Pick 4. Specify location for vertex 5 or <define faces>: Pick 5. Specify location for vertex 6 or <define faces>: Pick 6. Specify location for vertex 7 or <define faces>: Pick 7. Specify location for vertex 8 or <define faces>: Pick 8.

Chapter 23 Creating 3D Surfaces 667

Specify location for vertex 9 or <define faces>: Pick 9. Specify location for vertex 10 or <define faces>: Pick 0. Specify location for vertex 11 or <define faces>: Pick !. Specify location for vertex 12 or <define faces>: Pick @. Specify location for vertex 13 or <define faces>:

Face 1, vertex 1: Enter a vertex number or [Color/Layer]: 1 Face 1, vertex 2: Enter a vertex number or [Color/Layer] <next face>: 2

Face 1, vertex 3: Enter a vertex number or [Color/Layer] <next face>: 3

Face 1, vertex 4: Enter a vertex number or [Color/Layer] <next face>: 4

Face 1, vertex 5: Enter a vertex number or [Color/Layer] <next face>: 5

Face 1, vertex 6: Enter a vertex number or [Color/Layer] <next face>: 6

Face 1, vertex 7: Enter a vertex number or [Color/Layer] <next face>:

Face 2, vertex 1: Enter a vertex number or [Color/Layer]: 12 Face 2, vertex 2: Enter a vertex number or [Color/Layer] <next face>: 6

Face 2, vertex 3: Enter a vertex number or [Color/Layer] <next face>: 5

Face 2, vertex 4: Enter a vertex number or [Color/Layer] <next face>: 11

Face 2, vertex 5: Enter a vertex number or [Color/Layer] <next face>:

Face 3, vertex 1: Enter a vertex number or [Color/Layer]: 5 Face 3, vertex 2: Enter a vertex number or [Color/Layer] <next face>: 11

Face 3, vertex 3: Enter a vertex number or [Color/Layer] <next face>: 10

Face 3, vertex 4: Enter a vertex number or [Color/Layer] <next face>: 4

Face 3, vertex 5: Enter a vertex number or [Color/Layer] <next face>:

Face 4, vertex 1: Enter a vertex number or [Color/Layer]: 10 Face 4, vertex 2: Enter a vertex number or [Color/Layer] <next face>: 4

Face 4, vertex 3: Enter a vertex number or [Color/Layer] <next face>: 3

Face 4, vertex 4: Enter a vertex number or [Color/Layer] <next face>: 9

Face 4, vertex 5: Enter a vertex number or [Color/Layer] <next face>:

Face 5, vertex 1: Enter a vertex number or [Color/Layer]: 3 Face 5, vertex 2: Enter a vertex number or [Color/Layer] <next face>: 9

Face 5, vertex 3: Enter a vertex number or [Color/Layer] <next face>: 8

668 Part IV Drawing in Three Dimensions

Face 5, vertex 4: Enter a vertex number or [Color/Layer] <next face>: 2

Face 5, vertex 5: Enter a vertex number or [Color/Layer] <next face>:

Face 6, vertex 1: Enter a vertex number or [Color/Layer]: 8 Face 6, vertex 2: Enter a vertex number or [Color/Layer] <next face>: 2

Face 6, vertex 3: Enter a vertex number or [Color/Layer] <next face>: 1

Face 6, vertex 4: Enter a vertex number or [Color/Layer] <next face>: 7

Face 6, vertex 5: Enter a vertex number or [Color/Layer] <next face>:

Face 7, vertex 1: Enter a vertex number or [Color/Layer]: 7 Face 7, vertex 2: Enter a vertex number or [Color/Layer] <next face>: 8

Face 7, vertex 3: Enter a vertex number or [Color/Layer] <next face>: 9

Face 7, vertex 4: Enter a vertex number or [Color/Layer] <next face>: 10

Face 7, vertex 5: Enter a vertex number or [Color/Layer] <next face>: 11

Face 7, vertex 6: Enter a vertex number or [Color/Layer] <next face>: 12

Face 7, vertex 7: Enter a vertex number or [Color/Layer] <next face>:

Face 8, vertex 1: Enter a vertex number or [Color/Layer]:

4.Choose View Hide to see the final result.

5.Save your drawing. It should look like Figure 23-9.

Figure 23-9: The completed hexagonal night table.